From 04ea0f76f8994496675c76c3ffe13f6511dc8339 Mon Sep 17 00:00:00 2001
From: Zack Middleton <zack@cloemail.com>
Date: Thu, 13 Jun 2024 15:37:24 -0500
Subject: [PATCH] ioquake3 resync to commit c1ab47a7 from 60dfabbe

Use nanosleep(2) instead of usleep(3)
Makefile: fix compilation on FreeBSD
Update macOS version for GitHub CI
OpenGL2: Add OpenGL ES 2.0+ support
OpenGL2: Add run-time support for unsigned short indexes
OpenGL2: Use CPU vertex animation if too few vertex attributes
Merge pull request #664 from zturtleman/opengles2
OpenGL2: Fix issues running under WebGL
OpenGL2: Fallback to OpenGL ES if OpenGL fails
Add minimal emscripten support
Fix emscripten build directions
Use BASEGAME for emscripten assets
Fix using emscripten 3.1.27+
Allow building for emscripten with "emmake make"
Add -ffast-math for emscripten to match other platforms
Add .vscode and baseq3 to gitignore
Rebuild every target if Makefile changes
ioquake3.html replaces Emscripten-generated HTML shell
Get rid of "Nothing to be done for _.zip" message
Fix build when specifying PLATFORM=emscripten manually instead of using emmake
Silence compiler warnings
Support debug Emscripten build
Speed up GitHub Actions with -j
Add GitHub Actions workflow for web/Emscripten
Add Emscripten to README
Add DEPEND_MAKEFILE to disable rebuild on Makefile edit
Add BUILD_RENDERER_OPENGL1 to disable opengl1
Clean up emscripten in Makefile
Make emscripten --preload-file opt-in
Allow web client to use unzipped QVMs
Customize the web client HTML file
Add support for overriding basegame to web client
Add support for mods to web client
Rename client-config.json based on CLIENTBIN
---
 .github/workflows/build.yml                   |  31 ++-
 engine/Makefile                               | 160 +++++++++++-
 engine/code/autoupdater/autoupdater.c         |   5 +-
 engine/code/client/cl_avi.c                   |   5 +-
 engine/code/qcommon/q_platform.h              |  16 ++
 engine/code/renderercommon/qgl.h              |   2 +-
 .../code/renderergl2/glsl/depthblur_fp.glsl   |   5 +-
 engine/code/renderergl2/glsl/ssao_fp.glsl     |   3 +-
 engine/code/renderergl2/tr_backend.c          |  29 ++-
 engine/code/renderergl2/tr_bsp.c              |   2 +-
 engine/code/renderergl2/tr_cmds.c             |  15 +-
 engine/code/renderergl2/tr_extensions.c       | 143 +++++++++-
 engine/code/renderergl2/tr_flares.c           |   8 +
 engine/code/renderergl2/tr_glsl.c             | 244 ++++++++++++------
 engine/code/renderergl2/tr_image.c            | 188 +++++++++++++-
 engine/code/renderergl2/tr_init.c             |  95 +++++--
 engine/code/renderergl2/tr_local.h            |  22 +-
 engine/code/renderergl2/tr_mesh.c             |  19 +-
 engine/code/renderergl2/tr_model.c            |   6 +
 engine/code/renderergl2/tr_postprocess.c      |   2 +
 engine/code/renderergl2/tr_shade.c            |  11 +-
 engine/code/renderergl2/tr_vbo.c              |  67 +++--
 engine/code/sdl/sdl_glimp.c                   | 207 ++++++++++-----
 engine/code/sys/sys_main.c                    |   8 +
 engine/code/sys/sys_unix.c                    |   7 +-
 engine/code/web/client-config.json            |  47 ++++
 engine/code/web/client.html                   | 116 +++++++++
 engine/docs/README.md                         |  39 +++
 engine/docs/opengl2-readme.md                 |   8 +
 29 files changed, 1263 insertions(+), 247 deletions(-)
 create mode 100644 engine/code/web/client-config.json
 create mode 100644 engine/code/web/client.html

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 05dd8736..4f3adf12 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,7 +12,7 @@ jobs:
         sudo apt-get update
         sudo apt-get install libsdl2-dev
     - name: Compile
-      run: make release -C engine
+      run: make release -j$(nproc) -C engine
       env:
         ARCHIVE: 1
     - uses: actions/upload-artifact@v4
@@ -27,7 +27,7 @@ jobs:
     - name: Compile
       run: |
         choco install zip
-        make release -C engine
+        make release -j $env:NUMBER_OF_PROCESSORS -C engine
       env:
         ARCHIVE: 1
     - uses: actions/upload-artifact@v4
@@ -36,14 +36,37 @@ jobs:
         path: engine/build/*.zip
   macos:
     name: macOS
-    runs-on: macos-11
+    runs-on: macos-12
     steps:
     - uses: actions/checkout@v4
     - name: Compile
-      run: make release -C engine
+      run: make release -j$(sysctl -n hw.logicalcpu) -C engine
       env:
         ARCHIVE: 1
     - uses: actions/upload-artifact@v4
       with:
         name: macOS
         path: engine/build/*.zip
+  web:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/checkout@v4
+      with:
+        repository: emscripten-core/emsdk
+        path: emsdk
+    - name: Install Dependencies
+      run: |
+        cd emsdk
+        ./emsdk install 3.1.58
+        ./emsdk activate 3.1.58
+    - name: Compile
+      env:
+        ARCHIVE: 1
+      run: |
+        source emsdk/emsdk_env.sh
+        emmake make release -j$(nproc) -C engine
+    - uses: actions/upload-artifact@v4
+      with:
+        name: Web
+        path: engine/build/*.zip
diff --git a/engine/Makefile b/engine/Makefile
index ff1e56a7..886e85a9 100644
--- a/engine/Makefile
+++ b/engine/Makefile
@@ -40,6 +40,9 @@ endif
 ifndef BUILD_MISSIONPACK
   BUILD_MISSIONPACK= 0
 endif
+ifndef BUILD_RENDERER_OPENGL1
+  BUILD_RENDERER_OPENGL1=
+endif
 ifndef BUILD_RENDERER_OPENGL2
   BUILD_RENDERER_OPENGL2=
 endif
@@ -48,7 +51,7 @@ ifndef BUILD_AUTOUPDATER  # DON'T build unless you mean to!
 endif
 
 # ioquake3 git commit that this is based on
-IOQ3_REVISION = 60dfabbe
+IOQ3_REVISION = c1ab47a7
 
 #############################################################################
 #
@@ -64,6 +67,11 @@ ifeq ($(COMPILE_PLATFORM),cygwin)
   PLATFORM=mingw32
 endif
 
+# detect "emmake make"
+ifeq ($(findstring /emcc,$(CC)),/emcc)
+  PLATFORM=emscripten
+endif
+
 ifndef PLATFORM
 PLATFORM=$(COMPILE_PLATFORM)
 endif
@@ -295,6 +303,7 @@ LIBTOMCRYPTSRCDIR=$(AUTOUPDATERSRCDIR)/rsa_tools/libtomcrypt-1.17
 TOMSFASTMATHSRCDIR=$(AUTOUPDATERSRCDIR)/rsa_tools/tomsfastmath-0.13.1
 LOKISETUPDIR=misc/setup
 NSISDIR=misc/nsis
+WEBDIR=$(MOUNT_DIR)/web
 SDLHDIR=$(MOUNT_DIR)/SDL2
 LIBSDIR=$(MOUNT_DIR)/libs
 
@@ -826,6 +835,8 @@ else # ifdef MINGW
 #############################################################################
 
 ifeq ($(PLATFORM),freebsd)
+  # Use the default C compiler
+  TOOLS_CC=cc
 
   # flags
   BASE_CFLAGS = \
@@ -1061,6 +1072,67 @@ ifeq ($(PLATFORM),sunos)
 
 else # ifeq sunos
 
+#############################################################################
+# SETUP AND BUILD -- emscripten
+#############################################################################
+
+ifeq ($(PLATFORM),emscripten)
+
+  ifneq ($(findstring /emcc,$(CC)),/emcc)
+    CC=emcc
+  endif
+  ARCH=wasm32
+  BINEXT=.js
+
+  # dlopen(), opengl1, and networking are not functional
+  USE_RENDERER_DLOPEN=0
+  USE_OPENAL_DLOPEN=0
+  BUILD_GAME_SO=0
+  BUILD_RENDERER_OPENGL1=0
+  BUILD_SERVER=0
+
+  CLIENT_CFLAGS+=-s USE_SDL=2
+
+  CLIENT_LDFLAGS+=-s TOTAL_MEMORY=256MB
+  CLIENT_LDFLAGS+=-s STACK_SIZE=5MB
+  CLIENT_LDFLAGS+=-s MIN_WEBGL_VERSION=1 -s MAX_WEBGL_VERSION=2
+
+  # The HTML file can use these functions to load extra files before the game starts.
+  CLIENT_LDFLAGS+=-s EXPORTED_RUNTIME_METHODS=FS,addRunDependency,removeRunDependency
+  CLIENT_LDFLAGS+=-s EXIT_RUNTIME=1
+  CLIENT_LDFLAGS+=-s EXPORT_ES6
+  CLIENT_LDFLAGS+=-s EXPORT_NAME=ioquake3
+
+  # Game data files can be packaged by emcc into a .data file that lives next to the wasm bundle
+  # and added to the virtual filesystem before the game starts. This requires the game data to be
+  # present at build time and it can't be changed afterward.
+  # For more flexibility, game data files can be loaded from a web server at runtime by listing
+  # them in client-config.json. This way they don't have to be present at build time and can be
+  # changed later.
+  ifeq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+    ifeq ($(wildcard $(BASEGAME)/*),)
+      $(error "No files in '$(BASEGAME)' directory for emscripten to preload.")
+    endif
+    CLIENT_LDFLAGS+=--preload-file $(BASEGAME)
+  endif
+
+  OPTIMIZEVM = -O3
+  OPTIMIZE = $(OPTIMIZEVM) -ffast-math
+
+  # These allow a warning-free build.
+  # Some of these warnings may actually be legit problems and should be fixed at some point.
+  BASE_CFLAGS+=-Wno-deprecated-non-prototype -Wno-dangling-else -Wno-implicit-const-int-float-conversion -Wno-misleading-indentation -Wno-format-overflow -Wno-logical-not-parentheses -Wno-absolute-value
+
+  DEBUG_CFLAGS=-g3 -O0 # -fsanitize=address -fsanitize=undefined
+  # Emscripten needs debug compiler flags to be passed to the linker as well
+  DEBUG_LDFLAGS=$(DEBUG_CFLAGS)
+
+  SHLIBEXT=wasm
+  SHLIBCFLAGS=-fPIC
+  SHLIBLDFLAGS=-s SIDE_MODULE
+
+else # ifeq emscripten
+
 #############################################################################
 # SETUP AND BUILD -- GENERIC
 #############################################################################
@@ -1079,6 +1151,7 @@ endif #OpenBSD
 endif #NetBSD
 endif #IRIX
 endif #SunOS
+endif #emscripten
 
 ifndef CC
   CC=gcc
@@ -1115,12 +1188,18 @@ endif
 
 ifneq ($(BUILD_CLIENT),0)
   ifneq ($(USE_RENDERER_DLOPEN),0)
-    TARGETS += $(B)/$(CLIENTBIN)$(FULLBINEXT) $(B)/renderer_opengl1_$(SHLIBNAME)
+    TARGETS += $(B)/$(CLIENTBIN)$(FULLBINEXT)
+
+    ifneq ($(BUILD_RENDERER_OPENGL1),0)
+      TARGETS += $(B)/renderer_opengl1_$(SHLIBNAME)
+    endif
     ifneq ($(BUILD_RENDERER_OPENGL2),0)
       TARGETS += $(B)/renderer_opengl2_$(SHLIBNAME)
     endif
   else
-    TARGETS += $(B)/$(CLIENTBIN)$(FULLBINEXT)
+    ifneq ($(BUILD_RENDERER_OPENGL1),0)
+      TARGETS += $(B)/$(CLIENTBIN)$(FULLBINEXT)
+    endif
     ifneq ($(BUILD_RENDERER_OPENGL2),0)
       TARGETS += $(B)/$(CLIENTBIN)_opengl2$(FULLBINEXT)
     endif
@@ -1167,6 +1246,42 @@ ifneq ($(BUILD_AUTOUPDATER),0)
   TARGETS += $(B)/$(AUTOUPDATER_BIN)
 endif
 
+ifeq ($(PLATFORM),emscripten)
+  ifneq ($(BUILD_SERVER),0)
+    GENERATEDTARGETS += $(B)/$(SERVERBIN).$(ARCH).wasm
+    ifeq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+      GENERATEDTARGETS += $(B)/$(SERVERBIN).$(ARCH).data
+    endif
+  endif
+
+  ifneq ($(BUILD_CLIENT),0)
+    TARGETS += $(B)/$(CLIENTBIN).html
+    ifneq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+      TARGETS += $(B)/$(CLIENTBIN)-config.json
+    endif
+
+    ifneq ($(USE_RENDERER_DLOPEN),0)
+      GENERATEDTARGETS += $(B)/$(CLIENTBIN).$(ARCH).wasm
+      ifeq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+        GENERATEDTARGETS += $(B)/$(CLIENTBIN).$(ARCH).data
+      endif
+    else
+      ifneq ($(BUILD_RENDERER_OPENGL1),0)
+        GENERATEDTARGETS += $(B)/$(CLIENTBIN).$(ARCH).wasm
+        ifeq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+          GENERATEDTARGETS += $(B)/$(CLIENTBIN).$(ARCH).data
+        endif
+      endif
+      ifneq ($(BUILD_RENDERER_OPENGL2),0)
+        GENERATEDTARGETS += $(B)/$(CLIENTBIN)_opengl2.$(ARCH).wasm
+        ifeq ($(EMSCRIPTEN_PRELOAD_FILE),1)
+          GENERATEDTARGETS += $(B)/$(CLIENTBIN)_opengl2.$(ARCH).data
+        endif
+      endif
+    endif
+  endif
+endif
+
 ifeq ($(USE_OPENAL),1)
   CLIENT_CFLAGS += -DUSE_OPENAL
   ifeq ($(USE_OPENAL_DLOPEN),1)
@@ -1451,7 +1566,8 @@ all: debug release
 debug:
 	@$(MAKE) targets B=$(BD) CFLAGS="$(CFLAGS) $(BASE_CFLAGS) $(DEPEND_CFLAGS)" \
 	  OPTIMIZE="$(DEBUG_CFLAGS)" OPTIMIZEVM="$(DEBUG_CFLAGS)" \
-	  CLIENT_CFLAGS="$(CLIENT_CFLAGS)" SERVER_CFLAGS="$(SERVER_CFLAGS)" V=$(V)
+	  CLIENT_CFLAGS="$(CLIENT_CFLAGS)" SERVER_CFLAGS="$(SERVER_CFLAGS)" V=$(V) \
+	  LDFLAGS="$(LDFLAGS) $(DEBUG_LDFLAGS)"
 
 release:
 	@$(MAKE) targets B=$(BR) CFLAGS="$(CFLAGS) $(BASE_CFLAGS) $(DEPEND_CFLAGS)" \
@@ -1488,6 +1604,7 @@ ifneq ($(BUILD_CLIENT),0)
 endif
 
 NAKED_TARGETS=$(shell echo $(TARGETS) | sed -e "s!$(B)/!!g")
+NAKED_GENERATEDTARGETS=$(shell echo $(GENERATEDTARGETS) | sed -e "s!$(B)/!!g")
 
 print_list=-@for i in $(1); \
      do \
@@ -1546,6 +1663,7 @@ endif
 	@echo ""
 	@echo "  Output:"
 	$(call print_list, $(NAKED_TARGETS))
+	$(call print_list, $(NAKED_GENERATEDTARGETS))
 	@echo ""
 ifneq ($(TARGETS),)
   ifndef DEBUG_MAKEFILE
@@ -1562,9 +1680,10 @@ endif
 ifneq ($(PLATFORM),darwin)
   ifdef ARCHIVE
 	@rm -f $@
-	@(cd $(B) && zip -r9 ../../$@ $(NAKED_TARGETS))
+	@(cd $(B) && zip -r9 ../../$@ $(NAKED_TARGETS) $(NAKED_GENERATEDTARGETS))
   endif
 endif
+	@:
 
 makedirs:
 	@$(MKDIR) $(B)/autoupdater
@@ -1920,10 +2039,15 @@ Q3OBJ = \
 ifdef MINGW
   Q3OBJ += \
     $(B)/client/con_passive.o
+else
+ifeq ($(PLATFORM),emscripten)
+  Q3OBJ += \
+    $(B)/client/con_passive.o
 else
   Q3OBJ += \
     $(B)/client/con_tty.o
 endif
+endif
 
 Q3R2OBJ = \
   $(B)/renderergl2/tr_animation.o \
@@ -3084,6 +3208,19 @@ $(B)/$(MISSIONPACK)/qcommon/%.asm: $(CMDIR)/%.c $(Q3LCC)
 	$(DO_Q3LCC_MISSIONPACK)
 
 
+#############################################################################
+# EMSCRIPTEN
+#############################################################################
+
+$(B)/$(CLIENTBIN).html: $(WEBDIR)/client.html
+	$(echo_cmd) "SED $@"
+	$(Q)sed 's/__CLIENTBIN__/$(CLIENTBIN)/g;s/__BASEGAME__/$(BASEGAME)/g;s/__EMSCRIPTEN_PRELOAD_FILE__/$(EMSCRIPTEN_PRELOAD_FILE)/g' < $< > $@
+
+$(B)/$(CLIENTBIN)-config.json: $(WEBDIR)/client-config.json
+	$(echo_cmd) "CP $@"
+	$(Q)cp $< $@
+
+
 #############################################################################
 # MISC
 #############################################################################
@@ -3107,13 +3244,18 @@ ifneq ($(BUILD_GAME_SO),0)
 endif
 
 ifneq ($(BUILD_CLIENT),0)
-	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/$(CLIENTBIN)$(FULLBINEXT) $(COPYBINDIR)/$(CLIENTBIN)$(FULLBINEXT)
   ifneq ($(USE_RENDERER_DLOPEN),0)
+	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/$(CLIENTBIN)$(FULLBINEXT) $(COPYBINDIR)/$(CLIENTBIN)$(FULLBINEXT)
+    ifneq ($(BUILD_RENDERER_OPENGL1),0)
 	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/renderer_opengl1_$(SHLIBNAME) $(COPYBINDIR)/renderer_opengl1_$(SHLIBNAME)
+    endif
     ifneq ($(BUILD_RENDERER_OPENGL2),0)
 	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/renderer_opengl2_$(SHLIBNAME) $(COPYBINDIR)/renderer_opengl2_$(SHLIBNAME)
     endif
   else
+    ifneq ($(BUILD_RENDERER_OPENGL1),0)
+	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/$(CLIENTBIN)$(FULLBINEXT) $(COPYBINDIR)/$(CLIENTBIN)$(FULLBINEXT)
+    endif
     ifneq ($(BUILD_RENDERER_OPENGL2),0)
 	$(INSTALL) $(STRIP_FLAG) -m 0755 $(BR)/$(CLIENTBIN)_opengl2$(FULLBINEXT) $(COPYBINDIR)/$(CLIENTBIN)_opengl2$(FULLBINEXT)
     endif
@@ -3164,6 +3306,7 @@ clean2:
 	@rm -f $(OBJ_D_FILES)
 	@rm -f $(STRINGOBJ)
 	@rm -f $(TARGETS)
+	@rm -f $(GENERATEDTARGETS)
 
 toolsclean: toolsclean-debug toolsclean-release
 
@@ -3203,6 +3346,11 @@ dist:
 # DEPENDENCIES
 #############################################################################
 
+# Rebuild every target if Makefile or Makefile.local changes
+ifneq ($(DEPEND_MAKEFILE),0)
+.EXTRA_PREREQS:= $(MAKEFILE_LIST)
+endif
+
 ifneq ($(B),)
   OBJ_D_FILES=$(filter %.d,$(OBJ:%.o=%.d))
   TOOLSOBJ_D_FILES=$(filter %.d,$(TOOLSOBJ:%.o=%.d))
diff --git a/engine/code/autoupdater/autoupdater.c b/engine/code/autoupdater/autoupdater.c
index 4a052027..e013a1f4 100644
--- a/engine/code/autoupdater/autoupdater.c
+++ b/engine/code/autoupdater/autoupdater.c
@@ -933,10 +933,13 @@ static void waitToApplyUpdates(void)
                OS forcibly closes the pipe), we will unblock. Then we can loop on
                kill() until the process is truly gone. */
             int x = 0;
+            struct timespec req;
+            req.tv_sec = 0;
+            req.tv_nsec = 100000000;
             read(3, &x, sizeof (x));
             info("Pipe has closed, waiting for process to fully go away now.");
             while (kill(options.waitforprocess, 0) == 0) {
-                usleep(100000);
+                nanosleep(&req, NULL);
             }
             #endif
         }
diff --git a/engine/code/client/cl_avi.c b/engine/code/client/cl_avi.c
index 2f0dffd6..00cf7b1d 100644
--- a/engine/code/client/cl_avi.c
+++ b/engine/code/client/cl_avi.c
@@ -357,11 +357,12 @@ qboolean CL_OpenAVIForWriting( const char *fileName )
   else
     afd.motionJpeg = qfalse;
 
-  // Buffers only need to store RGB pixels.
+  // Capture buffer stores RGB pixels but OpenGL ES reads RGBA and converts to RGB in-place.
+  // Encode buffer only needs to store RGB pixels.
   // Allocate a bit more space for the capture buffer to account for possible
   // padding at the end of pixel lines, and padding for alignment
   #define MAX_PACK_LEN 16
-  afd.cBuffer = Z_Malloc((afd.width * 3 + MAX_PACK_LEN - 1) * afd.height + MAX_PACK_LEN - 1);
+  afd.cBuffer = Z_Malloc((afd.width * 4 + MAX_PACK_LEN - 1) * afd.height + MAX_PACK_LEN - 1);
   // raw avi files have pixel lines start on 4-byte boundaries
   afd.eBuffer = Z_Malloc(PAD(afd.width * 3, AVI_LINE_PADDING) * afd.height);
 
diff --git a/engine/code/qcommon/q_platform.h b/engine/code/qcommon/q_platform.h
index 72dbfe1d..53a53264 100644
--- a/engine/code/qcommon/q_platform.h
+++ b/engine/code/qcommon/q_platform.h
@@ -290,6 +290,22 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 #endif
 
+//================================================================== EMSCRIPTEN ===
+
+#ifdef __EMSCRIPTEN__
+
+#define OS_STRING "emscripten"
+#define ID_INLINE inline
+#define PATH_SEP '/'
+
+#define ARCH_STRING "wasm32"
+
+#define Q3_LITTLE_ENDIAN
+
+#define DLL_EXT ".wasm"
+
+#endif
+
 //================================================================== Q3VM ===
 
 #ifdef Q3_VM
diff --git a/engine/code/renderercommon/qgl.h b/engine/code/renderercommon/qgl.h
index 38f9919f..f226e408 100644
--- a/engine/code/renderercommon/qgl.h
+++ b/engine/code/renderercommon/qgl.h
@@ -80,7 +80,6 @@ extern void (APIENTRYP qglUnlockArraysEXT) (void);
 	GLE(void, TexParameterf, GLenum target, GLenum pname, GLfloat param) \
 	GLE(void, TexParameteri, GLenum target, GLenum pname, GLint param) \
 	GLE(void, TexSubImage2D, GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels) \
-	GLE(void, Translatef, GLfloat x, GLfloat y, GLfloat z) \
 	GLE(void, Viewport, GLint x, GLint y, GLsizei width, GLsizei height) \
 
 // OpenGL 1.0/1.1 and OpenGL ES 1.x but not OpenGL 3.2 core profile
@@ -98,6 +97,7 @@ extern void (APIENTRYP qglUnlockArraysEXT) (void);
 	GLE(void, ShadeModel, GLenum mode) \
 	GLE(void, TexCoordPointer, GLint size, GLenum type, GLsizei stride, const GLvoid *ptr) \
 	GLE(void, TexEnvf, GLenum target, GLenum pname, GLfloat param) \
+	GLE(void, Translatef, GLfloat x, GLfloat y, GLfloat z) \
 	GLE(void, VertexPointer, GLint size, GLenum type, GLsizei stride, const GLvoid *ptr) \
 
 // OpenGL 1.0/1.1 and 3.2 core profile but not OpenGL ES 1.x
diff --git a/engine/code/renderergl2/glsl/depthblur_fp.glsl b/engine/code/renderergl2/glsl/depthblur_fp.glsl
index d63df88a..205ee451 100644
--- a/engine/code/renderergl2/glsl/depthblur_fp.glsl
+++ b/engine/code/renderergl2/glsl/depthblur_fp.glsl
@@ -52,10 +52,9 @@ vec4 depthGaussian1D(sampler2D imageMap, sampler2D depthMap, vec2 tex, float zFa
 #endif
 
 	float zLimit = 5.0 / zFar;
-	int i, j;
-	for (i = 0; i < 2; i++)
+	for (int i = 0; i < 2; i++)
 	{
-		for (j = 1; j < BLUR_SIZE; j++)
+		for (int j = 1; j < BLUR_SIZE; j++)
 		{
 			vec2 offset = direction * (float(j) - 0.25) + nudge;
 #if defined(USE_DEPTH)
diff --git a/engine/code/renderergl2/glsl/ssao_fp.glsl b/engine/code/renderergl2/glsl/ssao_fp.glsl
index f3054404..2171f6e7 100644
--- a/engine/code/renderergl2/glsl/ssao_fp.glsl
+++ b/engine/code/renderergl2/glsl/ssao_fp.glsl
@@ -77,8 +77,7 @@ float ambientOcclusion(sampler2D depthMap, const vec2 tex, const float zFarDivZN
 
 	float invZFar = 1.0 / zFar;
 	float zLimit = 20.0 * invZFar;
-	int i;
-	for (i = 0; i < NUM_SAMPLES; i++)
+	for (int i = 0; i < NUM_SAMPLES; i++)
 	{
 		vec2 offset = rmat * poissonDisc[i] * offsetScale;
 		float sampleDiff = getLinearDepth(depthMap, tex + offset, zFarDivZNear) - sampleZ;
diff --git a/engine/code/renderergl2/tr_backend.c b/engine/code/renderergl2/tr_backend.c
index 0cffa4ee..71548779 100644
--- a/engine/code/renderergl2/tr_backend.c
+++ b/engine/code/renderergl2/tr_backend.c
@@ -732,6 +732,7 @@ void RE_StretchRaw (int x, int y, int w, int h, int cols, int rows, const byte *
 }
 
 void RE_UploadCinematic (int w, int h, int cols, int rows, const byte *data, int client, qboolean dirty) {
+	byte *buffer;
 	GLuint texture;
 
 	if (!tr.scratchImage[client])
@@ -746,7 +747,18 @@ void RE_UploadCinematic (int w, int h, int cols, int rows, const byte *data, int
 	if ( cols != tr.scratchImage[client]->width || rows != tr.scratchImage[client]->height ) {
 		tr.scratchImage[client]->width = tr.scratchImage[client]->uploadWidth = cols;
 		tr.scratchImage[client]->height = tr.scratchImage[client]->uploadHeight = rows;
-		qglTextureImage2DEXT(texture, GL_TEXTURE_2D, 0, GL_RGB8, cols, rows, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
+
+		if ( qglesMajorVersion >= 1 ) {
+			buffer = ri.Hunk_AllocateTempMemory( 3 * cols * rows );
+
+			R_ConvertTextureFormat( data, cols, rows, GL_RGB, GL_UNSIGNED_BYTE, buffer );
+			qglTextureImage2DEXT(texture, GL_TEXTURE_2D, 0, GL_RGB, cols, rows, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer);
+
+			ri.Hunk_FreeTempMemory( buffer );
+		} else {
+			qglTextureImage2DEXT(texture, GL_TEXTURE_2D, 0, GL_RGB8, cols, rows, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
+		}
+
 		qglTextureParameterfEXT(texture, GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 		qglTextureParameterfEXT(texture, GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 		qglTextureParameterfEXT(texture, GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
@@ -755,7 +767,16 @@ void RE_UploadCinematic (int w, int h, int cols, int rows, const byte *data, int
 		if (dirty) {
 			// otherwise, just subimage upload it so that drivers can tell we are going to be changing
 			// it and don't try and do a texture compression
-			qglTextureSubImage2DEXT(texture, GL_TEXTURE_2D, 0, 0, 0, cols, rows, GL_RGBA, GL_UNSIGNED_BYTE, data);
+			if ( qglesMajorVersion >= 1 ) {
+				buffer = ri.Hunk_AllocateTempMemory( 3 * cols * rows );
+
+				R_ConvertTextureFormat( data, cols, rows, GL_RGB, GL_UNSIGNED_BYTE, buffer );
+				qglTextureSubImage2DEXT(texture, GL_TEXTURE_2D, 0, 0, 0, cols, rows, GL_RGB, GL_UNSIGNED_BYTE, buffer);
+
+				ri.Hunk_FreeTempMemory( buffer );
+			} else {
+				qglTextureSubImage2DEXT(texture, GL_TEXTURE_2D, 0, 0, 0, cols, rows, GL_RGBA, GL_UNSIGNED_BYTE, data);
+			}
 		}
 	}
 }
@@ -1140,14 +1161,14 @@ const void	*RB_DrawSurfs( const void *data ) {
 			if (glRefConfig.occlusionQuery)
 			{
 				tr.sunFlareQueryActive[tr.sunFlareQueryIndex] = qtrue;
-				qglBeginQuery(GL_SAMPLES_PASSED, tr.sunFlareQuery[tr.sunFlareQueryIndex]);
+				qglBeginQuery(glRefConfig.occlusionQueryTarget, tr.sunFlareQuery[tr.sunFlareQueryIndex]);
 			}
 
 			RB_DrawSun(0.3, tr.sunFlareShader);
 
 			if (glRefConfig.occlusionQuery)
 			{
-				qglEndQuery(GL_SAMPLES_PASSED);
+				qglEndQuery(glRefConfig.occlusionQueryTarget);
 			}
 
 			FBO_Bind(oldFbo);
diff --git a/engine/code/renderergl2/tr_bsp.c b/engine/code/renderergl2/tr_bsp.c
index 15f5f3cd..57a4efc3 100644
--- a/engine/code/renderergl2/tr_bsp.c
+++ b/engine/code/renderergl2/tr_bsp.c
@@ -276,7 +276,7 @@ static	void R_LoadLightmaps( lump_t *l, lump_t *surfs ) {
 		tr.deluxemaps = ri.Hunk_Alloc( tr.numLightmaps * sizeof(image_t *), h_low );
 
 	textureInternalFormat = GL_RGBA8;
-	if (r_hdr->integer)
+	if (r_hdr->integer && !qglesMajorVersion)
 	{
 		// Check for the first hdr lightmap, if it exists, use GL_RGBA16 for textures.
 		char filename[MAX_QPATH];
diff --git a/engine/code/renderergl2/tr_cmds.c b/engine/code/renderergl2/tr_cmds.c
index 38ba45d2..2025c41d 100644
--- a/engine/code/renderergl2/tr_cmds.c
+++ b/engine/code/renderergl2/tr_cmds.c
@@ -348,7 +348,13 @@ void RE_BeginFrame( stereoFrame_t stereoFrame ) {
 	//
 	if ( r_measureOverdraw->integer )
 	{
-		if ( glConfig.stencilBits < 4 )
+		if ( qglesMajorVersion >= 1 && !glRefConfig.readStencil )
+		{
+			ri.Printf( PRINT_WARNING, "OpenGL ES needs GL_NV_read_stencil to read stencil bits to measure overdraw\n" );
+			ri.Cvar_Set( "r_measureOverdraw", "0" );
+			r_measureOverdraw->modified = qfalse;
+		}
+		else if ( glConfig.stencilBits < 4 )
 		{
 			ri.Printf( PRINT_ALL, "Warning: not enough stencil bits to measure overdraw: %d\n", glConfig.stencilBits );
 			ri.Cvar_Set( "r_measureOverdraw", "0" );
@@ -426,6 +432,13 @@ void RE_BeginFrame( stereoFrame_t stereoFrame ) {
 	}
 	else
 	{
+		if (qglesMajorVersion >= 1 && r_anaglyphMode->integer)
+		{
+			ri.Printf( PRINT_WARNING, "OpenGL ES does not support drawing to separate buffer for anaglyph mode\n" );
+			ri.Cvar_Set( "r_anaglyphMode", "0" );
+			r_anaglyphMode->modified = qfalse;
+		}
+
 		if(r_anaglyphMode->integer)
 		{
 			if(r_anaglyphMode->modified)
diff --git a/engine/code/renderergl2/tr_extensions.c b/engine/code/renderergl2/tr_extensions.c
index ebc985a9..856526bf 100644
--- a/engine/code/renderergl2/tr_extensions.c
+++ b/engine/code/renderergl2/tr_extensions.c
@@ -45,6 +45,17 @@ void GLimp_InitExtraExtensions(void)
 	if (strstr((char *)qglGetString(GL_RENDERER), "Intel"))
 		glRefConfig.intelGraphics = qtrue;
 
+	if (qglesMajorVersion)
+	{
+		glRefConfig.vaoCacheGlIndexType = GL_UNSIGNED_SHORT;
+		glRefConfig.vaoCacheGlIndexSize = sizeof(unsigned short);
+	}
+	else
+	{
+		glRefConfig.vaoCacheGlIndexType = GL_UNSIGNED_INT;
+		glRefConfig.vaoCacheGlIndexSize = sizeof(unsigned int);
+	}
+
 	// set DSA fallbacks
 #define GLE(ret, name, ...) qgl##name = GLDSA_##name;
 	QGL_EXT_direct_state_access_PROCS;
@@ -53,8 +64,107 @@ void GLimp_InitExtraExtensions(void)
 	// GL function loader, based on https://gist.github.com/rygorous/16796a0c876cf8a5f542caddb55bce8a
 #define GLE(ret, name, ...) qgl##name = (name##proc *) SDL_GL_GetProcAddress("gl" #name);
 
+	//
+	// OpenGL ES extensions
+	//
+	if (qglesMajorVersion)
+	{
+		if (!r_allowExtensions->integer)
+			goto done;
+
+		extension = "GL_EXT_occlusion_query_boolean";
+		if (qglesMajorVersion >= 3 || SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.occlusionQuery = qtrue;
+			glRefConfig.occlusionQueryTarget = GL_ANY_SAMPLES_PASSED;
+
+			if (qglesMajorVersion >= 3) {
+				QGL_ARB_occlusion_query_PROCS;
+			} else {
+				// GL_EXT_occlusion_query_boolean uses EXT suffix
+#undef GLE
+#define GLE(ret, name, ...) qgl##name = (name##proc *) SDL_GL_GetProcAddress("gl" #name "EXT");
+
+				QGL_ARB_occlusion_query_PROCS;
+
+#undef GLE
+#define GLE(ret, name, ...) qgl##name = (name##proc *) SDL_GL_GetProcAddress("gl" #name);
+			}
+
+			ri.Printf(PRINT_ALL, result[glRefConfig.occlusionQuery], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		// GL_NV_read_depth
+		extension = "GL_NV_read_depth";
+		if (SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.readDepth = qtrue;
+			ri.Printf(PRINT_ALL, result[glRefConfig.readDepth], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		// GL_NV_read_stencil
+		extension = "GL_NV_read_stencil";
+		if (SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.readStencil = qtrue;
+			ri.Printf(PRINT_ALL, result[glRefConfig.readStencil], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		// GL_EXT_shadow_samplers
+		extension = "GL_EXT_shadow_samplers";
+		if (qglesMajorVersion >= 3 || SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.shadowSamplers = qtrue;
+			ri.Printf(PRINT_ALL, result[glRefConfig.shadowSamplers], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		// GL_OES_standard_derivatives
+		extension = "GL_OES_standard_derivatives";
+		if (qglesMajorVersion >= 3 || SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.standardDerivatives = qtrue;
+			ri.Printf(PRINT_ALL, result[glRefConfig.standardDerivatives], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		// GL_OES_element_index_uint
+		extension = "GL_OES_element_index_uint";
+		if (qglesMajorVersion >= 3 || SDL_GL_ExtensionSupported(extension))
+		{
+			glRefConfig.vaoCacheGlIndexType = GL_UNSIGNED_INT;
+			glRefConfig.vaoCacheGlIndexSize = sizeof(unsigned int);
+			ri.Printf(PRINT_ALL, result[1], extension);
+		}
+		else
+		{
+			ri.Printf(PRINT_ALL, result[2], extension);
+		}
+
+		goto done;
+	}
+
 	// OpenGL 1.5 - GL_ARB_occlusion_query
 	glRefConfig.occlusionQuery = qtrue;
+	glRefConfig.occlusionQueryTarget = GL_SAMPLES_PASSED;
 	QGL_ARB_occlusion_query_PROCS;
 
 	// OpenGL 3.0 - GL_ARB_framebuffer_object
@@ -146,18 +256,6 @@ void GLimp_InitExtraExtensions(void)
 		ri.Printf(PRINT_ALL, result[2], extension);
 	}
 
-	// Determine GLSL version
-	if (1)
-	{
-		char version[256];
-
-		Q_strncpyz(version, (char *)qglGetString(GL_SHADING_LANGUAGE_VERSION), sizeof(version));
-
-		sscanf(version, "%d.%d", &glRefConfig.glslMajorVersion, &glRefConfig.glslMinorVersion);
-
-		ri.Printf(PRINT_ALL, "...using GLSL version %s\n", version);
-	}
-
 	glRefConfig.memInfo = MI_NONE;
 
 	// GL_NVX_gpu_memory_info
@@ -249,5 +347,26 @@ void GLimp_InitExtraExtensions(void)
 		ri.Printf(PRINT_ALL, result[2], extension);
 	}
 
+done:
+
+	// Determine GLSL version
+	if (1)
+	{
+		char version[256], *version_p;
+
+		Q_strncpyz(version, (char *)qglGetString(GL_SHADING_LANGUAGE_VERSION), sizeof(version));
+
+		// Skip leading text such as "OpenGL ES GLSL ES "
+		version_p = version;
+		while ( *version_p && !isdigit( *version_p ) )
+		{
+			version_p++;
+		}
+
+		sscanf(version_p, "%d.%d", &glRefConfig.glslMajorVersion, &glRefConfig.glslMinorVersion);
+
+		ri.Printf(PRINT_ALL, "...using GLSL version %s\n", version);
+	}
+
 #undef GLE
 }
diff --git a/engine/code/renderergl2/tr_flares.c b/engine/code/renderergl2/tr_flares.c
index fc83df7b..edf76822 100644
--- a/engine/code/renderergl2/tr_flares.c
+++ b/engine/code/renderergl2/tr_flares.c
@@ -478,6 +478,14 @@ void RB_RenderFlares (void) {
 		return;
 	}
 
+	if ( r_flares->modified ) {
+		if ( qglesMajorVersion >= 1 && !glRefConfig.readDepth ) {
+			ri.Printf( PRINT_WARNING, "OpenGL ES needs GL_NV_read_depth to read depth to determine if flares are visible\n" );
+			ri.Cvar_Set( "r_flares", "0" );
+		}
+		r_flares->modified = qfalse;
+	}
+
 	if(r_flareCoeff->modified)
 	{
 		R_SetFlareCoeff();
diff --git a/engine/code/renderergl2/tr_glsl.c b/engine/code/renderergl2/tr_glsl.c
index 2c834f10..39223bf6 100644
--- a/engine/code/renderergl2/tr_glsl.c
+++ b/engine/code/renderergl2/tr_glsl.c
@@ -249,11 +249,25 @@ static void GLSL_GetShaderHeader( GLenum shaderType, const GLchar *extra, char *
 	// HACK: abuse the GLSL preprocessor to turn GLSL 1.20 shaders into 1.30 ones
 	if(glRefConfig.glslMajorVersion > 1 || (glRefConfig.glslMajorVersion == 1 && glRefConfig.glslMinorVersion >= 30))
 	{
-		if (glRefConfig.glslMajorVersion > 1 || (glRefConfig.glslMajorVersion == 1 && glRefConfig.glslMinorVersion >= 50))
+		if (qglesMajorVersion >= 3 && glRefConfig.glslMajorVersion >= 3)
+			Q_strcat(dest, size, "#version 300 es\n");
+		else if (glRefConfig.glslMajorVersion > 1 || (glRefConfig.glslMajorVersion == 1 && glRefConfig.glslMinorVersion >= 50))
 			Q_strcat(dest, size, "#version 150\n");
 		else
 			Q_strcat(dest, size, "#version 130\n");
 
+		// `extra' may contain #extension which must be directly after #version
+		if (extra)
+		{
+			Q_strcat(dest, size, extra);
+		}
+
+		if (qglesMajorVersion >= 2)
+		{
+			Q_strcat(dest, size, "precision mediump float;\n");
+			Q_strcat(dest, size, "precision mediump sampler2DShadow;\n");
+		}
+
 		if(shaderType == GL_VERTEX_SHADER)
 		{
 			Q_strcat(dest, size, "#define attribute in\n");
@@ -272,8 +286,34 @@ static void GLSL_GetShaderHeader( GLenum shaderType, const GLchar *extra, char *
 	}
 	else
 	{
-		Q_strcat(dest, size, "#version 120\n");
-		Q_strcat(dest, size, "#define shadow2D(a,b) shadow2D(a,b).r \n");
+		if (qglesMajorVersion >= 2)
+		{
+			Q_strcat(dest, size, "#version 100\n");
+
+			if (extra)
+			{
+				Q_strcat(dest, size, extra);
+			}
+
+			Q_strcat(dest, size, "precision mediump float;\n");
+
+			if (glRefConfig.shadowSamplers)
+			{
+				Q_strcat(dest, size, "precision mediump sampler2DShadow;\n");
+				Q_strcat(dest, size, "#define shadow2D(a,b) shadow2DEXT(a,b)\n");
+			}
+		}
+		else
+		{
+			Q_strcat(dest, size, "#version 120\n");
+
+			if (extra)
+			{
+				Q_strcat(dest, size, extra);
+			}
+
+			Q_strcat(dest, size, "#define shadow2D(a,b) shadow2D(a,b).r\n");
+		}
 	}
 
 	// HACK: add some macros to avoid extra uniforms and save speed and code maintenance
@@ -361,11 +401,6 @@ static void GLSL_GetShaderHeader( GLenum shaderType, const GLchar *extra, char *
 		Q_strcat(dest, size, va("#define ROUGHNESS_MIPS float(%d)\n", numRoughnessMips));
 	}
 
-	if (extra)
-	{
-		Q_strcat(dest, size, extra);
-	}
-
 	// OK we added a lot of stuff but if we do something bad in the GLSL shaders then we want the proper line
 	// so we have to reset the line counting
 	Q_strcat(dest, size, "#line 0\n");
@@ -933,6 +968,15 @@ void GLSL_InitGPUShaders(void)
 
 	startTime = ri.Milliseconds();
 
+	// OpenGL ES may not have enough attributes to fit ones used for vertex animation
+	if ( glRefConfig.maxVertexAttribs > ATTR_INDEX_NORMAL2 ) {
+		ri.Printf(PRINT_ALL, "Using GPU vertex animation\n");
+		glRefConfig.gpuVertexAnimation = qtrue;
+	} else {
+		ri.Printf(PRINT_ALL, "Using CPU vertex animation\n");
+		glRefConfig.gpuVertexAnimation = qfalse;
+	}
+
 	for (i = 0; i < GENERICDEF_COUNT; i++)
 	{	
 		if ((i & GENERICDEF_USE_VERTEX_ANIMATION) && (i & GENERICDEF_USE_BONE_ANIMATION))
@@ -955,6 +999,9 @@ void GLSL_InitGPUShaders(void)
 
 		if (i & GENERICDEF_USE_VERTEX_ANIMATION)
 		{
+			if (!glRefConfig.gpuVertexAnimation)
+				continue;
+
 			Q_strcat(extradefines, 1024, "#define USE_VERTEX_ANIMATION\n");
 			attribs |= ATTR_POSITION2 | ATTR_NORMAL2;
 		}
@@ -1006,6 +1053,9 @@ void GLSL_InitGPUShaders(void)
 		if ((i & FOGDEF_USE_VERTEX_ANIMATION) && (i & FOGDEF_USE_BONE_ANIMATION))
 			continue;
 
+		if ((i & FOGDEF_USE_VERTEX_ANIMATION) && !glRefConfig.gpuVertexAnimation)
+			continue;
+
 		if ((i & FOGDEF_USE_BONE_ANIMATION) && !glRefConfig.glslMaxAnimatedBones)
 			continue;
 
@@ -1186,12 +1236,17 @@ void GLSL_InitGPUShaders(void)
 
 		if (i & LIGHTDEF_ENTITY_VERTEX_ANIMATION)
 		{
-			Q_strcat(extradefines, 1024, "#define USE_VERTEX_ANIMATION\n#define USE_MODELMATRIX\n");
-			attribs |= ATTR_POSITION2 | ATTR_NORMAL2;
+			Q_strcat(extradefines, 1024, "#define USE_MODELMATRIX\n");
 
-			if (r_normalMapping->integer)
+			if (glRefConfig.gpuVertexAnimation)
 			{
-				attribs |= ATTR_TANGENT2;
+				Q_strcat(extradefines, 1024, "#define USE_VERTEX_ANIMATION\n");
+				attribs |= ATTR_POSITION2 | ATTR_NORMAL2;
+
+				if (r_normalMapping->integer)
+				{
+					attribs |= ATTR_TANGENT2;
+				}
 			}
 		}
 		else if (i & LIGHTDEF_ENTITY_BONE_ANIMATION)
@@ -1226,6 +1281,9 @@ void GLSL_InitGPUShaders(void)
 		if ((i & SHADOWMAPDEF_USE_VERTEX_ANIMATION) && (i & SHADOWMAPDEF_USE_BONE_ANIMATION))
 			continue;
 
+		if ((i & SHADOWMAPDEF_USE_VERTEX_ANIMATION) && !glRefConfig.gpuVertexAnimation)
+			continue;
+
 		if ((i & SHADOWMAPDEF_USE_BONE_ANIMATION) && !glRefConfig.glslMaxAnimatedBones)
 			continue;
 
@@ -1350,86 +1408,110 @@ void GLSL_InitGPUShaders(void)
 	}
 
 
-	attribs = ATTR_POSITION | ATTR_TEXCOORD;
-	extradefines[0] = '\0';
-
-	if (r_shadowFilter->integer >= 1)
-		Q_strcat(extradefines, 1024, "#define USE_SHADOW_FILTER\n");
-
-	if (r_shadowFilter->integer >= 2)
-		Q_strcat(extradefines, 1024, "#define USE_SHADOW_FILTER2\n");
-
-	if (r_shadowCascadeZFar->integer != 0)
-		Q_strcat(extradefines, 1024, "#define USE_SHADOW_CASCADE\n");
-
-	Q_strcat(extradefines, 1024, va("#define r_shadowMapSize %f\n", r_shadowMapSize->value));
-	Q_strcat(extradefines, 1024, va("#define r_shadowCascadeZFar %f\n", r_shadowCascadeZFar->value));
-
-
-	if (!GLSL_InitGPUShader(&tr.shadowmaskShader, "shadowmask", attribs, qtrue, extradefines, qtrue, fallbackShader_shadowmask_vp, fallbackShader_shadowmask_fp))
-	{
-		ri.Error(ERR_FATAL, "Could not load shadowmask shader!");
-	}
-	
-	GLSL_InitUniforms(&tr.shadowmaskShader);
-
-	GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SCREENDEPTHMAP, TB_COLORMAP);
-	GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP,  TB_SHADOWMAP);
-	GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP2, TB_SHADOWMAP2);
-	GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP3, TB_SHADOWMAP3);
-	GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP4, TB_SHADOWMAP4);
-
-	GLSL_FinishGPUShader(&tr.shadowmaskShader);
-
-	numEtcShaders++;
-
-
-	attribs = ATTR_POSITION | ATTR_TEXCOORD;
-	extradefines[0] = '\0';
-
-	if (!GLSL_InitGPUShader(&tr.ssaoShader, "ssao", attribs, qtrue, extradefines, qtrue, fallbackShader_ssao_vp, fallbackShader_ssao_fp))
-	{
-		ri.Error(ERR_FATAL, "Could not load ssao shader!");
-	}
-
-	GLSL_InitUniforms(&tr.ssaoShader);
-
-	GLSL_SetUniformInt(&tr.ssaoShader, UNIFORM_SCREENDEPTHMAP, TB_COLORMAP);
-
-	GLSL_FinishGPUShader(&tr.ssaoShader);
-
-	numEtcShaders++;
-
-
-	for (i = 0; i < 4; i++)
+	// GLSL 1.10+ or GL_EXT_shadow_samplers extension are required for sampler2DShadow type
+	if (glRefConfig.glslMajorVersion > 1 || (glRefConfig.glslMajorVersion == 1 && glRefConfig.glslMinorVersion >= 10)
+	    || glRefConfig.shadowSamplers)
 	{
 		attribs = ATTR_POSITION | ATTR_TEXCOORD;
 		extradefines[0] = '\0';
 
-		if (i & 1)
-			Q_strcat(extradefines, 1024, "#define USE_VERTICAL_BLUR\n");
-		else
-			Q_strcat(extradefines, 1024, "#define USE_HORIZONTAL_BLUR\n");
-
-		if (!(i & 2))
-			Q_strcat(extradefines, 1024, "#define USE_DEPTH\n");
-
-
-		if (!GLSL_InitGPUShader(&tr.depthBlurShader[i], "depthBlur", attribs, qtrue, extradefines, qtrue, fallbackShader_depthblur_vp, fallbackShader_depthblur_fp))
+		if (qglesMajorVersion < 3 && glRefConfig.shadowSamplers)
 		{
-			ri.Error(ERR_FATAL, "Could not load depthBlur shader!");
+			Q_strcat(extradefines, 1024, "#extension GL_EXT_shadow_samplers : enable\n");
 		}
-		
-		GLSL_InitUniforms(&tr.depthBlurShader[i]);
 
-		GLSL_SetUniformInt(&tr.depthBlurShader[i], UNIFORM_SCREENIMAGEMAP, TB_COLORMAP);
-		GLSL_SetUniformInt(&tr.depthBlurShader[i], UNIFORM_SCREENDEPTHMAP, TB_LIGHTMAP);
+		if (r_shadowFilter->integer >= 1)
+			Q_strcat(extradefines, 1024, "#define USE_SHADOW_FILTER\n");
 
-		GLSL_FinishGPUShader(&tr.depthBlurShader[i]);
+		if (r_shadowFilter->integer >= 2)
+			Q_strcat(extradefines, 1024, "#define USE_SHADOW_FILTER2\n");
+
+		if (r_shadowCascadeZFar->integer != 0)
+			Q_strcat(extradefines, 1024, "#define USE_SHADOW_CASCADE\n");
+
+		Q_strcat(extradefines, 1024, va("#define r_shadowMapSize %f\n", r_shadowMapSize->value));
+		Q_strcat(extradefines, 1024, va("#define r_shadowCascadeZFar %f\n", r_shadowCascadeZFar->value));
+
+		if (!GLSL_InitGPUShader(&tr.shadowmaskShader, "shadowmask", attribs, qtrue, extradefines, qtrue, fallbackShader_shadowmask_vp, fallbackShader_shadowmask_fp))
+		{
+			ri.Error(ERR_FATAL, "Could not load shadowmask shader!");
+		}
+	
+		GLSL_InitUniforms(&tr.shadowmaskShader);
+
+		GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SCREENDEPTHMAP, TB_COLORMAP);
+		GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP,  TB_SHADOWMAP);
+		GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP2, TB_SHADOWMAP2);
+		GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP3, TB_SHADOWMAP3);
+		GLSL_SetUniformInt(&tr.shadowmaskShader, UNIFORM_SHADOWMAP4, TB_SHADOWMAP4);
+
+		GLSL_FinishGPUShader(&tr.shadowmaskShader);
 
 		numEtcShaders++;
 	}
 
+
+	// GLSL 1.10+ or GL_OES_standard_derivatives extension are required for dFdx() and dFdy() GLSL functions
+	if (glRefConfig.glslMajorVersion > 1 || (glRefConfig.glslMajorVersion == 1 && glRefConfig.glslMinorVersion >= 10)
+	    || glRefConfig.standardDerivatives)
+	{
+		attribs = ATTR_POSITION | ATTR_TEXCOORD;
+		extradefines[0] = '\0';
+
+		if (qglesMajorVersion < 3 && glRefConfig.standardDerivatives)
+		{
+			Q_strcat(extradefines, 1024, "#extension GL_OES_standard_derivatives : enable\n");
+		}
+
+		if (!GLSL_InitGPUShader(&tr.ssaoShader, "ssao", attribs, qtrue, extradefines, qtrue, fallbackShader_ssao_vp, fallbackShader_ssao_fp))
+		{
+			ri.Error(ERR_FATAL, "Could not load ssao shader!");
+		}
+
+		GLSL_InitUniforms(&tr.ssaoShader);
+
+		GLSL_SetUniformInt(&tr.ssaoShader, UNIFORM_SCREENDEPTHMAP, TB_COLORMAP);
+
+		GLSL_FinishGPUShader(&tr.ssaoShader);
+
+		numEtcShaders++;
+
+
+		for (i = 0; i < 4; i++)
+		{
+			attribs = ATTR_POSITION | ATTR_TEXCOORD;
+			extradefines[0] = '\0';
+
+			if (qglesMajorVersion < 3 && glRefConfig.standardDerivatives)
+			{
+				Q_strcat(extradefines, 1024, "#extension GL_OES_standard_derivatives : enable\n");
+			}
+
+			if (i & 1)
+				Q_strcat(extradefines, 1024, "#define USE_VERTICAL_BLUR\n");
+			else
+				Q_strcat(extradefines, 1024, "#define USE_HORIZONTAL_BLUR\n");
+
+			if (!(i & 2))
+				Q_strcat(extradefines, 1024, "#define USE_DEPTH\n");
+
+
+			if (!GLSL_InitGPUShader(&tr.depthBlurShader[i], "depthBlur", attribs, qtrue, extradefines, qtrue, fallbackShader_depthblur_vp, fallbackShader_depthblur_fp))
+			{
+				ri.Error(ERR_FATAL, "Could not load depthBlur shader!");
+			}
+		
+			GLSL_InitUniforms(&tr.depthBlurShader[i]);
+
+			GLSL_SetUniformInt(&tr.depthBlurShader[i], UNIFORM_SCREENIMAGEMAP, TB_COLORMAP);
+			GLSL_SetUniformInt(&tr.depthBlurShader[i], UNIFORM_SCREENDEPTHMAP, TB_LIGHTMAP);
+
+			GLSL_FinishGPUShader(&tr.depthBlurShader[i]);
+
+			numEtcShaders++;
+		}
+	}
+
 #if 0
 	attribs = ATTR_POSITION | ATTR_TEXCOORD;
 	extradefines[0] = '\0';
@@ -1462,7 +1544,7 @@ void GLSL_ShutdownGPUShaders(void)
 
 	ri.Printf(PRINT_ALL, "------- GLSL_ShutdownGPUShaders -------\n");
 
-	for (i = 0; i < ATTR_INDEX_COUNT; i++)
+	for (i = 0; i < ATTR_INDEX_COUNT && i < glRefConfig.maxVertexAttribs; i++)
 		qglDisableVertexAttribArray(i);
 
 	GL_BindNullProgram();
diff --git a/engine/code/renderergl2/tr_image.c b/engine/code/renderergl2/tr_image.c
index 101513b6..0e829d51 100644
--- a/engine/code/renderergl2/tr_image.c
+++ b/engine/code/renderergl2/tr_image.c
@@ -1455,6 +1455,106 @@ byte	mipBlendColors[16][4] = {
 	{0,0,255,128},
 };
 
+/*
+==================
+R_ConvertTextureFormat
+
+Convert RGBA unsigned byte to specified format and type
+==================
+*/
+#define ROW_PADDING( width, bpp, alignment ) PAD( (width) * (bpp), (alignment) ) - (width) * (bpp)
+void R_ConvertTextureFormat( const byte *in, int width, int height, GLenum format, GLenum type, byte *out )
+{
+	int x, y, rowPadding;
+	int unpackAlign = 4; // matches GL_UNPACK_ALIGNMENT default
+
+	if ( format == GL_RGB && type == GL_UNSIGNED_BYTE )
+	{
+		rowPadding = ROW_PADDING( width, 3, unpackAlign );
+
+		for ( y = 0; y < height; y++ )
+		{
+			for ( x = 0; x < width; x++ )
+			{
+				*out++ = *in++;
+				*out++ = *in++;
+				*out++ = *in++;
+				in++;
+			}
+
+			out += rowPadding;
+		}
+	}
+	else if ( format == GL_LUMINANCE && type == GL_UNSIGNED_BYTE )
+	{
+		rowPadding = ROW_PADDING( width, 1, unpackAlign );
+
+		for ( y = 0; y < height; y++ )
+		{
+			for ( x = 0; x < width; x++ )
+			{
+				*out++ = *in++; // red
+				in += 3;
+			}
+
+			out += rowPadding;
+		}
+	}
+	else if ( format == GL_LUMINANCE_ALPHA && type == GL_UNSIGNED_BYTE )
+	{
+		rowPadding = ROW_PADDING( width, 2, unpackAlign );
+
+		for ( y = 0; y < height; y++ )
+		{
+			for ( x = 0; x < width; x++ )
+			{
+				*out++ = *in++; // red
+				in += 2;
+				*out++ = *in++; // alpha
+			}
+
+			out += rowPadding;
+		}
+	}
+	else if ( format == GL_RGB && type == GL_UNSIGNED_SHORT_5_6_5 )
+	{
+		rowPadding = ROW_PADDING( width, 2, unpackAlign );
+
+		for ( y = 0; y < height; y++ )
+		{
+			for ( x = 0; x < width; x++, in += 4, out += 2 )
+			{
+				*((unsigned short*)out) = ( (unsigned short)( in[0] >> 3 ) << 11 )
+					    | ( (unsigned short)( in[1] >> 2 ) << 5 )
+					    | ( (unsigned short)( in[2] >> 3 ) << 0 );
+			}
+
+			out += rowPadding;
+		}
+	}
+	else if ( format == GL_RGBA && type == GL_UNSIGNED_SHORT_4_4_4_4 )
+	{
+		rowPadding = ROW_PADDING( width, 2, unpackAlign );
+
+		for ( y = 0; y < height; y++ )
+		{
+			for ( x = 0; x < width; x++, in += 4, out += 2 )
+			{
+				*((unsigned short*)out) = ( (unsigned short)( in[0] >> 4 ) << 12 )
+					    | ( (unsigned short)( in[1] >> 4 ) << 8 )
+					    | ( (unsigned short)( in[2] >> 4 ) << 4 )
+					    | ( (unsigned short)( in[3] >> 4 ) << 0 );
+			}
+
+			out += rowPadding;
+		}
+	}
+	else
+	{
+		ri.Error( ERR_DROP, "Unable to convert RGBA image to OpenGL format 0x%X and type 0x%X", format, type );
+	}
+}
+
 static void RawImage_SwizzleRA( byte *data, int width, int height )
 {
 	int i;
@@ -1944,18 +2044,20 @@ static GLenum PixelDataFormatFromInternalFormat(GLenum internalFormat)
 	}
 }
 
-static void RawImage_UploadTexture(GLuint texture, byte *data, int x, int y, int width, int height, GLenum target, GLenum picFormat, int numMips, GLenum internalFormat, imgType_t type, imgFlags_t flags, qboolean subtexture )
+static void RawImage_UploadTexture(GLuint texture, byte *data, int x, int y, int width, int height, GLenum target, GLenum picFormat, GLenum dataFormat, GLenum dataType, int numMips, GLenum internalFormat, imgType_t type, imgFlags_t flags, qboolean subtexture )
 {
-	GLenum dataFormat, dataType;
 	qboolean rgtc = internalFormat == GL_COMPRESSED_RG_RGTC2;
 	qboolean rgba8 = picFormat == GL_RGBA8 || picFormat == GL_SRGB8_ALPHA8_EXT;
 	qboolean rgba = rgba8 || picFormat == GL_RGBA16;
 	qboolean mipmap = !!(flags & IMGFLAG_MIPMAP);
 	int size, miplevel;
 	qboolean lastMip = qfalse;
+	byte *formatBuffer = NULL;
 
-	dataFormat = PixelDataFormatFromInternalFormat(internalFormat);
-	dataType = picFormat == GL_RGBA16 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_BYTE;
+	if (qglesMajorVersion && rgba8 && (dataFormat != GL_RGBA || dataType != GL_UNSIGNED_BYTE))
+	{
+		formatBuffer = ri.Hunk_AllocateTempMemory(4 * width * height);
+	}
 
 	miplevel = 0;
 	do
@@ -1974,6 +2076,11 @@ static void RawImage_UploadTexture(GLuint texture, byte *data, int x, int y, int
 
 			if (rgba8 && rgtc)
 				RawImage_UploadToRgtc2Texture(texture, miplevel, x, y, width, height, data);
+			else if (formatBuffer)
+			{
+				R_ConvertTextureFormat(data, width, height, dataFormat, dataType, formatBuffer);
+				qglTextureSubImage2DEXT(texture, target, miplevel, x, y, width, height, dataFormat, dataType, formatBuffer);
+			}
 			else
 				qglTextureSubImage2DEXT(texture, target, miplevel, x, y, width, height, dataFormat, dataType, data);
 		}
@@ -2007,6 +2114,9 @@ static void RawImage_UploadTexture(GLuint texture, byte *data, int x, int y, int
 		}
 	}
 	while (!lastMip);
+
+	if (formatBuffer != NULL)
+		ri.Hunk_FreeTempMemory(formatBuffer);
 }
 
 
@@ -2016,7 +2126,7 @@ Upload32
 
 ===============
 */
-static void Upload32(byte *data, int x, int y, int width, int height, GLenum picFormat, int numMips, image_t *image, qboolean scaled)
+static void Upload32(byte *data, int x, int y, int width, int height, GLenum picFormat, GLenum dataFormat, GLenum dataType, int numMips, image_t *image, qboolean scaled)
 {
 	int			i, c;
 	byte		*scan;
@@ -2071,7 +2181,7 @@ static void Upload32(byte *data, int x, int y, int width, int height, GLenum pic
 		for (i = 0; i < 6; i++)
 		{
 			int w2 = width, h2 = height;
-			RawImage_UploadTexture(image->texnum, data, x, y, width, height, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, picFormat, numMips, internalFormat, type, flags, qfalse);
+			RawImage_UploadTexture(image->texnum, data, x, y, width, height, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, picFormat, dataFormat, dataType, numMips, internalFormat, type, flags, qfalse);
 			for (c = numMips; c; c--)
 			{
 				data += CalculateMipSize(w2, h2, picFormat);
@@ -2082,7 +2192,7 @@ static void Upload32(byte *data, int x, int y, int width, int height, GLenum pic
 	}
 	else
 	{
-		RawImage_UploadTexture(image->texnum, data, x, y, width, height, GL_TEXTURE_2D, picFormat, numMips, internalFormat, type, flags, qfalse);
+		RawImage_UploadTexture(image->texnum, data, x, y, width, height, GL_TEXTURE_2D, picFormat, dataFormat, dataType, numMips, internalFormat, type, flags, qfalse);
 	}
 
 	GL_CheckErrors();
@@ -2108,7 +2218,7 @@ image_t *R_CreateImage2( const char *name, byte *pic, int width, int height, GLe
 	qboolean    picmip = !!(flags & IMGFLAG_PICMIP);
 	qboolean    lastMip;
 	GLenum textureTarget = cubemap ? GL_TEXTURE_CUBE_MAP : GL_TEXTURE_2D;
-	GLenum dataFormat;
+	GLenum dataFormat, dataType;
 
 	if (strlen(name) >= MAX_QPATH ) {
 		ri.Error (ERR_DROP, "R_CreateImage: \"%s\" is too long", name);
@@ -2140,6 +2250,53 @@ image_t *R_CreateImage2( const char *name, byte *pic, int width, int height, GLe
 	if (!internalFormat)
 		internalFormat = RawImage_GetFormat(pic, width * height, picFormat, isLightmap, image->type, image->flags);
 
+	dataFormat = PixelDataFormatFromInternalFormat(internalFormat);
+	dataType = picFormat == GL_RGBA16 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_BYTE;
+
+	// Convert image data format for OpenGL ES, data is converted for each mip level
+	if (qglesMajorVersion)
+	{
+		switch (internalFormat)
+		{
+			case GL_LUMINANCE:
+			case GL_LUMINANCE8:
+				internalFormat = GL_LUMINANCE;
+				dataFormat = GL_LUMINANCE;
+				dataType = GL_UNSIGNED_BYTE;
+				break;
+			case GL_LUMINANCE_ALPHA:
+			case GL_LUMINANCE8_ALPHA8:
+				internalFormat = GL_LUMINANCE_ALPHA;
+				dataFormat = GL_LUMINANCE_ALPHA;
+				dataType = GL_UNSIGNED_BYTE;
+				break;
+			case GL_RGB:
+			case GL_RGB8:
+				internalFormat = GL_RGB;
+				dataFormat = GL_RGB;
+				dataType = GL_UNSIGNED_BYTE;
+				break;
+			case GL_RGB5:
+				internalFormat = GL_RGB;
+				dataFormat = GL_RGB;
+				dataType = GL_UNSIGNED_SHORT_5_6_5;
+				break;
+			case GL_RGBA:
+			case GL_RGBA8:
+				internalFormat = GL_RGBA;
+				dataFormat = GL_RGBA;
+				dataType = GL_UNSIGNED_BYTE;
+				break;
+			case GL_RGBA4:
+				internalFormat = GL_RGBA;
+				dataFormat = GL_RGBA;
+				dataType = GL_UNSIGNED_SHORT_4_4_4_4;
+				break;
+			default:
+				ri.Error( ERR_DROP, "Missing OpenGL ES support for image '%s' with internal format 0x%X\n", name, internalFormat );
+		}
+	}
+
 	image->internalFormat = internalFormat;
 
 	// Possibly scale image before uploading.
@@ -2164,7 +2321,6 @@ image_t *R_CreateImage2( const char *name, byte *pic, int width, int height, GLe
 	image->uploadHeight = height;
 
 	// Allocate texture storage so we don't have to worry about it later.
-	dataFormat = PixelDataFormatFromInternalFormat(internalFormat);
 	mipWidth = width;
 	mipHeight = height;
 	miplevel = 0;
@@ -2176,11 +2332,11 @@ image_t *R_CreateImage2( const char *name, byte *pic, int width, int height, GLe
 			int i;
 
 			for (i = 0; i < 6; i++)
-				qglTextureImage2DEXT(image->texnum, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, miplevel, internalFormat, mipWidth, mipHeight, 0, dataFormat, GL_UNSIGNED_BYTE, NULL);
+				qglTextureImage2DEXT(image->texnum, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, miplevel, internalFormat, mipWidth, mipHeight, 0, dataFormat, dataType, NULL);
 		}
 		else
 		{
-			qglTextureImage2DEXT(image->texnum, GL_TEXTURE_2D, miplevel, internalFormat, mipWidth, mipHeight, 0, dataFormat, GL_UNSIGNED_BYTE, NULL);
+			qglTextureImage2DEXT(image->texnum, GL_TEXTURE_2D, miplevel, internalFormat, mipWidth, mipHeight, 0, dataFormat, dataType, NULL);
 		}
 
 		mipWidth  = MAX(1, mipWidth >> 1);
@@ -2191,7 +2347,7 @@ image_t *R_CreateImage2( const char *name, byte *pic, int width, int height, GLe
 
 	// Upload data.
 	if (pic)
-		Upload32(pic, 0, 0, width, height, picFormat, numMips, image, scaled);
+		Upload32(pic, 0, 0, width, height, picFormat, dataFormat, dataType, numMips, image, scaled);
 
 	if (resampledBuffer != NULL)
 		ri.Hunk_FreeTempMemory(resampledBuffer);
@@ -2252,7 +2408,13 @@ image_t *R_CreateImage(const char *name, byte *pic, int width, int height, imgTy
 
 void R_UpdateSubImage( image_t *image, byte *pic, int x, int y, int width, int height, GLenum picFormat )
 {
-	Upload32(pic, x, y, width, height, picFormat, 0, image, qfalse);
+	GLenum dataFormat, dataType;
+
+	// TODO: This is fine for lightmaps but (unused) general RGBA images need to store dataFormat / dataType in image_t for OpenGL ES?
+	dataFormat = PixelDataFormatFromInternalFormat(image->internalFormat);
+	dataType = picFormat == GL_RGBA16 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_BYTE;
+
+	Upload32(pic, x, y, width, height, picFormat, dataFormat, dataType, 0, image, qfalse);
 }
 
 //===================================================================
diff --git a/engine/code/renderergl2/tr_init.c b/engine/code/renderergl2/tr_init.c
index bc71cedf..583c2f96 100644
--- a/engine/code/renderergl2/tr_init.c
+++ b/engine/code/renderergl2/tr_init.c
@@ -279,8 +279,16 @@ static void InitOpenGL( void )
 		qglGetIntegerv( GL_MAX_TEXTURE_IMAGE_UNITS, &temp );
 		glConfig.numTextureUnits = temp;
 
+		qglGetIntegerv( GL_MAX_VERTEX_ATTRIBS, &temp );
+		glRefConfig.maxVertexAttribs = temp;
+
 		// reserve 160 components for other uniforms
-		qglGetIntegerv( GL_MAX_VERTEX_UNIFORM_COMPONENTS, &temp );
+		if ( qglesMajorVersion ) {
+			qglGetIntegerv( GL_MAX_VERTEX_UNIFORM_VECTORS, &temp );
+			temp *= 4;
+		} else {
+			qglGetIntegerv( GL_MAX_VERTEX_UNIFORM_COMPONENTS, &temp );
+		}
 		glRefConfig.glslMaxAnimatedBones = Com_Clamp( 0, IQM_MAX_JOINTS, ( temp - 160 ) / 16 );
 		if ( glRefConfig.glslMaxAnimatedBones < 12 ) {
 			glRefConfig.glslMaxAnimatedBones = 0;
@@ -451,21 +459,43 @@ Return value must be freed with ri.Hunk_FreeTempMemory()
 byte *RB_ReadPixels(int x, int y, int width, int height, size_t *offset, int *padlen)
 {
 	byte *buffer, *bufstart;
-	int padwidth, linelen;
-	GLint packAlign;
-	
+	int padwidth, linelen, bytesPerPixel;
+	int yin, xin, xout;
+	GLint packAlign, format;
+
+	// OpenGL ES is only required to support reading GL_RGBA
+	if (qglesMajorVersion >= 1) {
+		format = GL_RGBA;
+		bytesPerPixel = 4;
+	} else {
+		format = GL_RGB;
+		bytesPerPixel = 3;
+	}
+
 	qglGetIntegerv(GL_PACK_ALIGNMENT, &packAlign);
-	
-	linelen = width * 3;
+
+	linelen = width * bytesPerPixel;
 	padwidth = PAD(linelen, packAlign);
-	
+
 	// Allocate a few more bytes so that we can choose an alignment we like
 	buffer = ri.Hunk_AllocateTempMemory(padwidth * height + *offset + packAlign - 1);
-	
-	bufstart = PADP((intptr_t) buffer + *offset, packAlign);
 
-	qglReadPixels(x, y, width, height, GL_RGB, GL_UNSIGNED_BYTE, bufstart);
-	
+	bufstart = PADP((intptr_t) buffer + *offset, packAlign);
+	qglReadPixels(x, y, width, height, format, GL_UNSIGNED_BYTE, bufstart);
+
+	linelen = width * 3;
+
+	// Convert RGBA to RGB, in place, line by line
+	if (format == GL_RGBA) {
+		for (yin = 0; yin < height; yin++) {
+			for (xin = 0, xout = 0; xout < linelen; xin += 4, xout += 3) {
+				bufstart[yin*padwidth + xout + 0] = bufstart[yin*padwidth + xin + 0];
+				bufstart[yin*padwidth + xout + 1] = bufstart[yin*padwidth + xin + 1];
+				bufstart[yin*padwidth + xout + 2] = bufstart[yin*padwidth + xin + 2];
+			}
+		}
+	}
+
 	*offset = bufstart - buffer;
 	*padlen = padwidth - linelen;
 	
@@ -877,9 +907,10 @@ const void *RB_TakeVideoFrameCmd( const void *data )
 {
 	const videoFrameCommand_t	*cmd;
 	byte				*cBuf;
-	size_t				memcount, linelen;
+	size_t				memcount, bytesPerPixel, linelen, avilinelen;
 	int				padwidth, avipadwidth, padlen, avipadlen;
-	GLint packAlign;
+	int				yin, xin, xout;
+	GLint packAlign, format;
 
 	// finish any 2D drawing if needed
 	if(tess.numIndexes)
@@ -887,20 +918,32 @@ const void *RB_TakeVideoFrameCmd( const void *data )
 
 	cmd = (const videoFrameCommand_t *)data;
 	
+	// OpenGL ES is only required to support reading GL_RGBA
+	if (qglesMajorVersion >= 1) {
+		format = GL_RGBA;
+		bytesPerPixel = 4;
+	} else {
+		format = GL_RGB;
+		bytesPerPixel = 3;
+	}
+
 	qglGetIntegerv(GL_PACK_ALIGNMENT, &packAlign);
 
-	linelen = cmd->width * 3;
+	linelen = cmd->width * bytesPerPixel;
 
 	// Alignment stuff for glReadPixels
 	padwidth = PAD(linelen, packAlign);
 	padlen = padwidth - linelen;
+
+	avilinelen = cmd->width * 3;
+
 	// AVI line padding
-	avipadwidth = PAD(linelen, AVI_LINE_PADDING);
-	avipadlen = avipadwidth - linelen;
+	avipadwidth = PAD(avilinelen, AVI_LINE_PADDING);
+	avipadlen = avipadwidth - avilinelen;
 
 	cBuf = PADP(cmd->captureBuffer, packAlign);
 		
-	qglReadPixels(0, 0, cmd->width, cmd->height, GL_RGB,
+	qglReadPixels(0, 0, cmd->width, cmd->height, format,
 		GL_UNSIGNED_BYTE, cBuf);
 
 	memcount = padwidth * cmd->height;
@@ -911,7 +954,21 @@ const void *RB_TakeVideoFrameCmd( const void *data )
 
 	if(cmd->motionJpeg)
 	{
-		memcount = RE_SaveJPGToBuffer(cmd->encodeBuffer, linelen * cmd->height,
+		// Convert RGBA to RGB, in place, line by line
+		if (format == GL_RGBA) {
+			linelen = cmd->width * 3;
+			padlen = padwidth - linelen;
+
+			for (yin = 0; yin < cmd->height; yin++) {
+				for (xin = 0, xout = 0; xout < linelen; xin += 4, xout += 3) {
+					cBuf[yin*padwidth + xout + 0] = cBuf[yin*padwidth + xin + 0];
+					cBuf[yin*padwidth + xout + 1] = cBuf[yin*padwidth + xin + 1];
+					cBuf[yin*padwidth + xout + 2] = cBuf[yin*padwidth + xin + 2];
+				}
+			}
+		}
+
+		memcount = RE_SaveJPGToBuffer(cmd->encodeBuffer, avilinelen * cmd->height,
 			r_aviMotionJpegQuality->integer,
 			cmd->width, cmd->height, cBuf, padlen);
 		ri.CL_WriteAVIVideoFrame(cmd->encodeBuffer, memcount);
@@ -934,7 +991,7 @@ const void *RB_TakeVideoFrameCmd( const void *data )
 				*destptr++ = srcptr[2];
 				*destptr++ = srcptr[1];
 				*destptr++ = srcptr[0];
-				srcptr += 3;
+				srcptr += bytesPerPixel;
 			}
 			
 			Com_Memset(destptr, '\0', avipadlen);
diff --git a/engine/code/renderergl2/tr_local.h b/engine/code/renderergl2/tr_local.h
index 6a0aa36f..9f46866f 100644
--- a/engine/code/renderergl2/tr_local.h
+++ b/engine/code/renderergl2/tr_local.h
@@ -49,8 +49,10 @@ QGL_ARB_vertex_array_object_PROCS;
 QGL_EXT_direct_state_access_PROCS;
 #undef GLE
 
-#define GL_INDEX_TYPE		GL_UNSIGNED_INT
-typedef unsigned int glIndex_t;
+#define GL_INDEX_TYPE		GL_UNSIGNED_SHORT
+typedef unsigned short glIndex_t;
+
+typedef unsigned int vaoCacheGlIndex_t;
 
 #define BUFFER_OFFSET(i) ((char *)NULL + (i))
 
@@ -1406,6 +1408,7 @@ typedef struct {
 	qboolean    intelGraphics;
 
 	qboolean	occlusionQuery;
+	GLenum		occlusionQueryTarget;
 
 	int glslMajorVersion;
 	int glslMinorVersion;
@@ -1429,6 +1432,18 @@ typedef struct {
 
 	qboolean vertexArrayObject;
 	qboolean directStateAccess;
+
+	int maxVertexAttribs;
+	qboolean gpuVertexAnimation;
+
+	GLenum vaoCacheGlIndexType; // GL_UNSIGNED_INT or GL_UNSIGNED_SHORT
+	size_t vaoCacheGlIndexSize; // must be <= sizeof( vaoCacheGlIndex_t )
+
+	// OpenGL ES extensions
+	qboolean readDepth;
+	qboolean readStencil;
+	qboolean shadowSamplers;
+	qboolean standardDerivatives;
 } glRefConfig_t;
 
 
@@ -2213,6 +2228,7 @@ void            R_VaoList_f(void);
 void            RB_UpdateTessVao(unsigned int attribBits);
 
 void VaoCache_Commit(void);
+void VaoCache_DrawElements(int numIndexes, int firstIndex);
 void VaoCache_Init(void);
 void VaoCache_BindVao(void);
 void VaoCache_CheckAdd(qboolean *endSurface, qboolean *recycleVertexBuffer, qboolean *recycleIndexBuffer, int numVerts, int numIndexes);
@@ -2502,5 +2518,7 @@ size_t RE_SaveJPGToBuffer(byte *buffer, size_t bufSize, int quality,
 void RE_TakeVideoFrame( int width, int height,
 		byte *captureBuffer, byte *encodeBuffer, qboolean motionJpeg );
 
+void R_ConvertTextureFormat( const byte *in, int width, int height, GLenum format, GLenum type, byte *out );
+
 
 #endif //TR_LOCAL_H
diff --git a/engine/code/renderergl2/tr_mesh.c b/engine/code/renderergl2/tr_mesh.c
index 4f2c6724..222b06d0 100644
--- a/engine/code/renderergl2/tr_mesh.c
+++ b/engine/code/renderergl2/tr_mesh.c
@@ -282,9 +282,10 @@ R_AddMD3Surfaces
 */
 void R_AddMD3Surfaces( trRefEntity_t *ent ) {
 	int				i;
-	mdvModel_t		*model = NULL;
-	mdvSurface_t	*surface = NULL;
-	shader_t		*shader = NULL;
+	mdvModel_t		*model;
+	mdvSurface_t	*surface;
+	void			*drawSurf;
+	shader_t		*shader;
 	int				cull;
 	int				lod;
 	int				fogNum;
@@ -382,6 +383,12 @@ void R_AddMD3Surfaces( trRefEntity_t *ent ) {
 			shader = tr.shaders[ surface->shaderIndexes[ ent->e.skinNum % surface->numShaderIndexes ] ];
 		}
 
+		if ( model->numVaoSurfaces > 0 ) {
+			drawSurf = &model->vaoSurfaces[i];
+		} else {
+			drawSurf = surface;
+		}
+
 		// we will add shadows even if the main object isn't visible in the view
 
 		// stencil shadows can't do personal models unless I polyhedron clip
@@ -390,7 +397,7 @@ void R_AddMD3Surfaces( trRefEntity_t *ent ) {
 			&& fogNum == 0
 			&& !(ent->e.renderfx & ( RF_NOSHADOW | RF_DEPTHHACK ) ) 
 			&& shader->sort == SS_OPAQUE ) {
-			R_AddDrawSurf( (void *)&model->vaoSurfaces[i], tr.shadowShader, 0, qfalse, qfalse, 0 );
+			R_AddDrawSurf( drawSurf, tr.shadowShader, 0, qfalse, qfalse, 0 );
 		}
 
 		// projection shadows work fine with personal models
@@ -398,12 +405,12 @@ void R_AddMD3Surfaces( trRefEntity_t *ent ) {
 			&& fogNum == 0
 			&& (ent->e.renderfx & RF_SHADOW_PLANE )
 			&& shader->sort == SS_OPAQUE ) {
-			R_AddDrawSurf( (void *)&model->vaoSurfaces[i], tr.projectionShadowShader, 0, qfalse, qfalse, 0 );
+			R_AddDrawSurf( drawSurf, tr.projectionShadowShader, 0, qfalse, qfalse, 0 );
 		}
 
 		// don't add third_person objects if not viewing through a portal
 		if ( !personalModel ) {
-			R_AddDrawSurf((void *)&model->vaoSurfaces[i], shader, fogNum, qfalse, qfalse, cubemapIndex );
+			R_AddDrawSurf( drawSurf, shader, fogNum, qfalse, qfalse, cubemapIndex );
 		}
 
 		surface++;
diff --git a/engine/code/renderergl2/tr_model.c b/engine/code/renderergl2/tr_model.c
index 0fdf60d8..7201be1b 100644
--- a/engine/code/renderergl2/tr_model.c
+++ b/engine/code/renderergl2/tr_model.c
@@ -664,6 +664,12 @@ static qboolean R_LoadMD3(model_t * mod, int lod, void *buffer, int bufferSize,
 		surf++;
 	}
 
+	if (mdvModel->numFrames > 1 && !glRefConfig.gpuVertexAnimation)
+	{
+		mdvModel->numVaoSurfaces = 0;
+		mdvModel->vaoSurfaces = NULL;
+	}
+	else
 	{
 		srfVaoMdvMesh_t *vaoSurf;
 
diff --git a/engine/code/renderergl2/tr_postprocess.c b/engine/code/renderergl2/tr_postprocess.c
index 3d71f304..ff9a25a1 100644
--- a/engine/code/renderergl2/tr_postprocess.c
+++ b/engine/code/renderergl2/tr_postprocess.c
@@ -290,6 +290,8 @@ static qboolean RB_UpdateSunFlareVis(void)
 		ri.Printf(PRINT_DEVELOPER, "Waited %d iterations\n", iter);
 	}
 	
+	// Note: On desktop OpenGL this is a sample count (glRefConfig.occlusionQueryTarget == GL_SAMPLES_PASSED)
+	// but on OpenGL ES this is a boolean (glRefConfig.occlusionQueryTarget == GL_ANY_SAMPLES_PASSED)
 	qglGetQueryObjectuiv(tr.sunFlareQuery[tr.sunFlareQueryIndex], GL_QUERY_RESULT, &sampleCount);
 	return sampleCount > 0;
 }
diff --git a/engine/code/renderergl2/tr_shade.c b/engine/code/renderergl2/tr_shade.c
index 21f9543a..dec35e52 100644
--- a/engine/code/renderergl2/tr_shade.c
+++ b/engine/code/renderergl2/tr_shade.c
@@ -40,7 +40,14 @@ R_DrawElements
 
 void R_DrawElements( int numIndexes, int firstIndex )
 {
-	qglDrawElements(GL_TRIANGLES, numIndexes, GL_INDEX_TYPE, BUFFER_OFFSET(firstIndex * sizeof(glIndex_t)));
+	if (tess.useCacheVao)
+	{
+		VaoCache_DrawElements(numIndexes, firstIndex);
+	}
+	else
+	{
+		qglDrawElements(GL_TRIANGLES, numIndexes, GL_INDEX_TYPE, BUFFER_OFFSET(firstIndex * sizeof(glIndex_t)));
+	}
 }
 
 
@@ -1720,6 +1727,8 @@ void RB_EndSurface( void ) {
 	tess.numIndexes = 0;
 	tess.numVertexes = 0;
 	tess.firstIndex = 0;
+	tess.useCacheVao = qfalse;
+	tess.useInternalVao = qfalse;
 
 	GLimp_LogComment( "----------\n" );
 }
diff --git a/engine/code/renderergl2/tr_vbo.c b/engine/code/renderergl2/tr_vbo.c
index df64f8bc..5094df18 100644
--- a/engine/code/renderergl2/tr_vbo.c
+++ b/engine/code/renderergl2/tr_vbo.c
@@ -676,7 +676,7 @@ static struct
 	srfVert_t vertexes[VAOCACHE_QUEUE_MAX_VERTEXES];
 	int vertexCommitSize;
 
-	glIndex_t indexes[VAOCACHE_QUEUE_MAX_INDEXES];
+	vaoCacheGlIndex_t indexes[VAOCACHE_QUEUE_MAX_INDEXES];
 	int indexCommitSize;
 }
 vcq;
@@ -687,18 +687,13 @@ vcq;
 // srfVert_t is 60 bytes
 // assuming each vert is referenced 4 times, need 16 bytes (4 glIndex_t) per vert
 // -> need about 4/15ths the space for indexes as vertexes
-#if GL_INDEX_TYPE == GL_UNSIGNED_SHORT
-#define VAOCACHE_VERTEX_BUFFER_SIZE (sizeof(srfVert_t) * USHRT_MAX)
-#define VAOCACHE_INDEX_BUFFER_SIZE (sizeof(glIndex_t) * USHRT_MAX * 4)
-#else // GL_UNSIGNED_INT
 #define VAOCACHE_VERTEX_BUFFER_SIZE (16 * 1024 * 1024)
 #define VAOCACHE_INDEX_BUFFER_SIZE (5 * 1024 * 1024)
-#endif
 
 typedef struct buffered_s
 {
-	void *data;
-	int size;
+	glIndex_t *indexes;
+	int numIndexes;
 	int bufferOffset;
 }
 buffered_t;
@@ -736,7 +731,7 @@ void VaoCache_Commit(void)
 			buffered_t *indexSet2 = indexSet;
 			for (surf = vcq.surfaces; surf < end; surf++, indexSet2++)
 			{
-				if (surf->indexes != indexSet2->data || (surf->numIndexes * sizeof(glIndex_t)) != indexSet2->size)
+				if (surf->indexes != indexSet2->indexes || surf->numIndexes != indexSet2->numIndexes)
 					break;
 			}
 
@@ -750,7 +745,7 @@ void VaoCache_Commit(void)
 	// If found, use it
 	if (indexSet < vc.surfaceIndexSets + vc.numSurfaces)
 	{
-		tess.firstIndex = indexSet->bufferOffset / sizeof(glIndex_t);
+		tess.firstIndex = indexSet->bufferOffset / glRefConfig.vaoCacheGlIndexSize;
 		//ri.Printf(PRINT_ALL, "firstIndex %d numIndexes %d as %d\n", tess.firstIndex, tess.numIndexes, (int)(batchLength - vc.batchLengths));
 		//ri.Printf(PRINT_ALL, "vc.numSurfaces %d vc.numBatches %d\n", vc.numSurfaces, vc.numBatches);
 	}
@@ -759,20 +754,21 @@ void VaoCache_Commit(void)
 	else
 	{
 		srfVert_t *dstVertex = vcq.vertexes;
-		glIndex_t *dstIndex = vcq.indexes;
+		vaoCacheGlIndex_t *dstIndex = vcq.indexes;
+		unsigned short *dstIndexUshort = (unsigned short *)vcq.indexes;
 
 		batchLength = vc.batchLengths + vc.numBatches;
 		*batchLength = vcq.numSurfaces;
 		vc.numBatches++;
 
-		tess.firstIndex = vc.indexOffset / sizeof(glIndex_t);
+		tess.firstIndex = vc.indexOffset / glRefConfig.vaoCacheGlIndexSize;
 		vcq.vertexCommitSize = 0;
 		vcq.indexCommitSize = 0;
 		for (surf = vcq.surfaces; surf < end; surf++)
 		{
 			glIndex_t *srcIndex = surf->indexes;
 			int vertexesSize = surf->numVerts * sizeof(srfVert_t);
-			int indexesSize = surf->numIndexes * sizeof(glIndex_t);
+			int indexesSize = surf->numIndexes * glRefConfig.vaoCacheGlIndexSize;
 			int i, indexOffset = (vc.vertexOffset + vcq.vertexCommitSize) / sizeof(srfVert_t);
 
 			Com_Memcpy(dstVertex, surf->vertexes, vertexesSize);
@@ -781,13 +777,21 @@ void VaoCache_Commit(void)
 			vcq.vertexCommitSize += vertexesSize;
 
 			indexSet = vc.surfaceIndexSets + vc.numSurfaces;
-			indexSet->data = surf->indexes;
-			indexSet->size = indexesSize;
+			indexSet->indexes = surf->indexes;
+			indexSet->numIndexes = surf->numIndexes;
 			indexSet->bufferOffset = vc.indexOffset + vcq.indexCommitSize;
 			vc.numSurfaces++;
 
-			for (i = 0; i < surf->numIndexes; i++)
-				*dstIndex++ = *srcIndex++ + indexOffset;
+			if (glRefConfig.vaoCacheGlIndexType == GL_UNSIGNED_SHORT)
+			{
+				for (i = 0; i < surf->numIndexes; i++)
+					*dstIndexUshort++ = *srcIndex++ + indexOffset;
+			}
+			else
+			{
+				for (i = 0; i < surf->numIndexes; i++)
+					*dstIndex++ = *srcIndex++ + indexOffset;
+			}
 
 			vcq.indexCommitSize += indexesSize;
 		}
@@ -810,9 +814,30 @@ void VaoCache_Commit(void)
 	}
 }
 
+void VaoCache_DrawElements(int numIndexes, int firstIndex)
+{
+	assert( glState.currentVao == vc.vao );
+
+	qglDrawElements(GL_TRIANGLES, numIndexes, glRefConfig.vaoCacheGlIndexType, BUFFER_OFFSET(firstIndex * glRefConfig.vaoCacheGlIndexSize));
+}
+
 void VaoCache_Init(void)
 {
-	vc.vao = R_CreateVao("VaoCache", NULL, VAOCACHE_VERTEX_BUFFER_SIZE, NULL, VAOCACHE_INDEX_BUFFER_SIZE, VAO_USAGE_DYNAMIC);
+	int vertexBufferSize;
+	int indexBufferSize;
+
+	if (glRefConfig.vaoCacheGlIndexType == GL_UNSIGNED_SHORT)
+	{
+		vertexBufferSize = sizeof(srfVert_t) * USHRT_MAX;
+		indexBufferSize = sizeof(unsigned short) * USHRT_MAX * 4;
+	}
+	else
+	{
+		vertexBufferSize = VAOCACHE_VERTEX_BUFFER_SIZE;
+		indexBufferSize = VAOCACHE_INDEX_BUFFER_SIZE;
+	}
+
+	vc.vao = R_CreateVao("VaoCache", NULL, vertexBufferSize, NULL, indexBufferSize, VAO_USAGE_DYNAMIC);
 
 	vc.vao->attribs[ATTR_INDEX_POSITION].enabled       = 1;
 	vc.vao->attribs[ATTR_INDEX_TEXCOORD].enabled       = 1;
@@ -881,7 +906,7 @@ void VaoCache_BindVao(void)
 void VaoCache_CheckAdd(qboolean *endSurface, qboolean *recycleVertexBuffer, qboolean *recycleIndexBuffer, int numVerts, int numIndexes)
 {
 	int vertexesSize = sizeof(srfVert_t) * numVerts;
-	int indexesSize = sizeof(glIndex_t) * numIndexes;
+	int indexesSize = glRefConfig.vaoCacheGlIndexSize * numIndexes;
 
 	if (vc.vao->vertexesSize < vc.vertexOffset + vcq.vertexCommitSize + vertexesSize)
 	{
@@ -924,7 +949,7 @@ void VaoCache_CheckAdd(qboolean *endSurface, qboolean *recycleVertexBuffer, qboo
 		*endSurface = qtrue;
 	}
 
-	if (VAOCACHE_QUEUE_MAX_INDEXES * sizeof(glIndex_t) < vcq.indexCommitSize + indexesSize)
+	if (VAOCACHE_QUEUE_MAX_INDEXES * glRefConfig.vaoCacheGlIndexSize < vcq.indexCommitSize + indexesSize)
 	{
 		//ri.Printf(PRINT_ALL, "out of queued indexes\n");
 		*endSurface = qtrue;
@@ -964,5 +989,5 @@ void VaoCache_AddSurface(srfVert_t *verts, int numVerts, glIndex_t *indexes, int
 	vcq.numSurfaces++;
 
 	vcq.vertexCommitSize += sizeof(srfVert_t) * numVerts;
-	vcq.indexCommitSize += sizeof(glIndex_t) * numIndexes;
+	vcq.indexCommitSize += glRefConfig.vaoCacheGlIndexSize * numIndexes;
 }
diff --git a/engine/code/sdl/sdl_glimp.c b/engine/code/sdl/sdl_glimp.c
index 30986ab1..2678dc71 100644
--- a/engine/code/sdl/sdl_glimp.c
+++ b/engine/code/sdl/sdl_glimp.c
@@ -52,6 +52,7 @@ cvar_t *r_allowSoftwareGL; // Don't abort out if a hardware visual can't be obta
 cvar_t *r_allowResize; // make window resizable
 cvar_t *r_centerWindow;
 cvar_t *r_sdlDriver;
+cvar_t *r_preferOpenGLES;
 
 int qglMajorVersion, qglMinorVersion;
 int qglesMajorVersion, qglesMinorVersion;
@@ -230,6 +231,27 @@ static void GLimp_DetectAvailableModes(void)
 	SDL_free( modes );
 }
 
+/*
+===============
+OpenGL ES compatibility
+===============
+*/
+static void APIENTRY GLimp_GLES_ClearDepth( GLclampd depth ) {
+	qglClearDepthf( depth );
+}
+
+static void APIENTRY GLimp_GLES_DepthRange( GLclampd near_val, GLclampd far_val ) {
+	qglDepthRangef( near_val, far_val );
+}
+
+static void APIENTRY GLimp_GLES_DrawBuffer( GLenum mode ) {
+	// unsupported
+}
+
+static void APIENTRY GLimp_GLES_PolygonMode( GLenum face, GLenum mode ) {
+	// unsupported
+}
+
 /*
 ===============
 GLimp_GetProcAddresses
@@ -306,8 +328,11 @@ static qboolean GLimp_GetProcAddresses( qboolean fixedFunction ) {
 			QGL_1_3_PROCS;
 			QGL_1_5_PROCS;
 			QGL_2_0_PROCS;
-			// error so this doesn't segfault due to NULL desktop GL functions being used
-			Com_Error( ERR_FATAL, "Unsupported OpenGL Version: %s", version );
+
+			qglClearDepth = GLimp_GLES_ClearDepth;
+			qglDepthRange = GLimp_GLES_DepthRange;
+			qglDrawBuffer = GLimp_GLES_DrawBuffer;
+			qglPolygonMode = GLimp_GLES_PolygonMode;
 		} else {
 			Com_Error( ERR_FATAL, "Unsupported OpenGL Version (%s), OpenGL 2.0 is required", version );
 		}
@@ -369,6 +394,12 @@ GLimp_SetMode
 */
 static int GLimp_SetMode(int mode, qboolean fullscreen, qboolean noborder, qboolean fixedFunction)
 {
+	struct GLimp_ContextType {
+		int profileMask;
+		int majorVersion;
+		int minorVersion;
+	} contexts[4];
+	int numContexts, type;
 	const char *glstring;
 	int perChannelColorBits;
 	int colorBits, depthBits, stencilBits;
@@ -499,6 +530,63 @@ static int GLimp_SetMode(int mode, qboolean fullscreen, qboolean noborder, qbool
 	stencilBits = r_stencilbits->value;
 	samples = r_ext_multisample->value;
 
+	numContexts = 0;
+
+	if ( !fixedFunction ) {
+		int profileMask;
+		qboolean preferOpenGLES;
+
+		SDL_GL_ResetAttributes();
+		SDL_GL_GetAttribute( SDL_GL_CONTEXT_PROFILE_MASK, &profileMask );
+
+		preferOpenGLES = ( r_preferOpenGLES->integer == 1 ||
+		                 ( r_preferOpenGLES->integer == -1 && profileMask == SDL_GL_CONTEXT_PROFILE_ES ) );
+
+		if ( preferOpenGLES ) {
+#ifdef __EMSCRIPTEN__
+			// WebGL 2.0 isn't fully backward compatible so you have to ask for it specifically
+			contexts[numContexts].profileMask = SDL_GL_CONTEXT_PROFILE_ES;
+			contexts[numContexts].majorVersion = 3;
+			contexts[numContexts].minorVersion = 0;
+			numContexts++;
+#endif
+
+			contexts[numContexts].profileMask = SDL_GL_CONTEXT_PROFILE_ES;
+			contexts[numContexts].majorVersion = 2;
+			contexts[numContexts].minorVersion = 0;
+			numContexts++;
+		}
+
+		contexts[numContexts].profileMask = SDL_GL_CONTEXT_PROFILE_CORE;
+		contexts[numContexts].majorVersion = 3;
+		contexts[numContexts].minorVersion = 2;
+		numContexts++;
+
+		contexts[numContexts].profileMask = 0;
+		contexts[numContexts].majorVersion = 2;
+		contexts[numContexts].minorVersion = 0;
+		numContexts++;
+
+		if ( !preferOpenGLES ) {
+#ifdef __EMSCRIPTEN__
+			contexts[numContexts].profileMask = SDL_GL_CONTEXT_PROFILE_ES;
+			contexts[numContexts].majorVersion = 3;
+			contexts[numContexts].minorVersion = 0;
+			numContexts++;
+#endif
+
+			contexts[numContexts].profileMask = SDL_GL_CONTEXT_PROFILE_ES;
+			contexts[numContexts].majorVersion = 2;
+			contexts[numContexts].minorVersion = 0;
+			numContexts++;
+		}
+	} else {
+		contexts[numContexts].profileMask = 0;
+		contexts[numContexts].majorVersion = 1;
+		contexts[numContexts].minorVersion = 1;
+		numContexts++;
+	}
+
 	for (i = 0; i < 16; i++)
 	{
 		int testColorBits, testDepthBits, testStencilBits;
@@ -631,82 +719,68 @@ static int GLimp_SetMode(int mode, qboolean fullscreen, qboolean noborder, qbool
 
 		SDL_SetWindowIcon( SDL_window, icon );
 
-		if (!fixedFunction)
-		{
-			int profileMask, majorVersion, minorVersion;
-			SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &profileMask);
-			SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &majorVersion);
-			SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &minorVersion);
+		for ( type = 0; type < numContexts; type++ ) {
+			char contextName[32];
 
-			ri.Printf(PRINT_ALL, "Trying to get an OpenGL 3.2 core context\n");
-			SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
-			SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
-			SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
-			if ((SDL_glContext = SDL_GL_CreateContext(SDL_window)) == NULL)
-			{
-				ri.Printf(PRINT_ALL, "SDL_GL_CreateContext failed: %s\n", SDL_GetError());
-				ri.Printf(PRINT_ALL, "Reverting to default context\n");
-
-				SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, profileMask);
-				SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, majorVersion);
-				SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, minorVersion);
+			switch ( contexts[type].profileMask ) {
+				default:
+				case 0:
+					Com_sprintf( contextName, sizeof( contextName ), "OpenGL %d.%d",
+					             contexts[type].majorVersion, contexts[type].minorVersion );
+					break;
+				case SDL_GL_CONTEXT_PROFILE_CORE:
+					Com_sprintf( contextName, sizeof( contextName ), "OpenGL %d.%d Core",
+					             contexts[type].majorVersion, contexts[type].minorVersion );
+					break;
+				case SDL_GL_CONTEXT_PROFILE_ES:
+					Com_sprintf( contextName, sizeof( contextName ), "OpenGL ES %d.%d",
+					             contexts[type].majorVersion, contexts[type].minorVersion );
+					break;
 			}
-			else
+
+			SDL_GL_SetAttribute( SDL_GL_CONTEXT_PROFILE_MASK, contexts[type].profileMask );
+			SDL_GL_SetAttribute( SDL_GL_CONTEXT_MAJOR_VERSION, contexts[type].majorVersion );
+			SDL_GL_SetAttribute( SDL_GL_CONTEXT_MINOR_VERSION, contexts[type].minorVersion );
+
+			SDL_glContext = SDL_GL_CreateContext( SDL_window );
+			if ( !SDL_glContext )
 			{
-				const char *renderer;
-
-				ri.Printf(PRINT_ALL, "SDL_GL_CreateContext succeeded.\n");
-
-				if ( GLimp_GetProcAddresses( fixedFunction ) )
-				{
-					renderer = (const char *)qglGetString(GL_RENDERER);
-				}
-				else
-				{
-					ri.Printf( PRINT_ALL, "GLimp_GetProcAddresses() failed for OpenGL 3.2 core context\n" );
-					renderer = NULL;
-				}
-
-				if (!renderer || (strstr(renderer, "Software Renderer") || strstr(renderer, "Software Rasterizer")))
-				{
-					if ( renderer )
-						ri.Printf(PRINT_ALL, "GL_RENDERER is %s, rejecting context\n", renderer);
-
-					GLimp_ClearProcAddresses();
-					SDL_GL_DeleteContext(SDL_glContext);
-					SDL_glContext = NULL;
-
-					SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, profileMask);
-					SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, majorVersion);
-					SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, minorVersion);
-				}
-			}
-		}
-		else
-		{
-			SDL_glContext = NULL;
-		}
-
-		if ( !SDL_glContext )
-		{
-			if( ( SDL_glContext = SDL_GL_CreateContext( SDL_window ) ) == NULL )
-			{
-				ri.Printf( PRINT_DEVELOPER, "SDL_GL_CreateContext failed: %s\n", SDL_GetError( ) );
-				SDL_DestroyWindow( SDL_window );
-				SDL_window = NULL;
+				ri.Printf( PRINT_ALL, "SDL_GL_CreateContext() for %s context failed: %s\n", contextName, SDL_GetError() );
 				continue;
 			}
 
 			if ( !GLimp_GetProcAddresses( fixedFunction ) )
 			{
-				ri.Printf( PRINT_ALL, "GLimp_GetProcAddresses() failed\n" );
+				ri.Printf( PRINT_ALL, "GLimp_GetProcAddresses() for %s context failed\n", contextName );
 				GLimp_ClearProcAddresses();
 				SDL_GL_DeleteContext( SDL_glContext );
 				SDL_glContext = NULL;
-				SDL_DestroyWindow( SDL_window );
-				SDL_window = NULL;
 				continue;
 			}
+
+			if ( contexts[type].profileMask == SDL_GL_CONTEXT_PROFILE_CORE ) {
+				const char *renderer;
+
+				renderer = (const char *)qglGetString( GL_RENDERER );
+
+				if ( !renderer || strstr( renderer, "Software Renderer" ) || strstr( renderer, "Software Rasterizer" ) )
+				{
+					ri.Printf( PRINT_ALL, "GL_RENDERER is %s, rejecting %s context\n", renderer, contextName );
+
+					GLimp_ClearProcAddresses();
+					SDL_GL_DeleteContext( SDL_glContext );
+					SDL_glContext = NULL;
+					continue;
+				}
+			}
+
+			break;
+		}
+
+		if ( !SDL_glContext ) {
+			SDL_DestroyWindow( SDL_window );
+			SDL_window = NULL;
+			continue;
 		}
 
 		qglClearColor( 0, 0, 0, 1 );
@@ -815,7 +889,7 @@ static void GLimp_InitExtensions( qboolean fixedFunction )
 	glConfig.textureCompression = TC_NONE;
 
 	// GL_EXT_texture_compression_s3tc
-	if ( SDL_GL_ExtensionSupported( "GL_ARB_texture_compression" ) &&
+	if ( ( QGLES_VERSION_ATLEAST( 2, 0 ) || SDL_GL_ExtensionSupported( "GL_ARB_texture_compression" ) ) &&
 	     SDL_GL_ExtensionSupported( "GL_EXT_texture_compression_s3tc" ) )
 	{
 		if ( r_ext_compressed_textures->value )
@@ -996,6 +1070,7 @@ void GLimp_Init( qboolean fixedFunction )
 	r_sdlDriver = ri.Cvar_Get( "r_sdlDriver", "", CVAR_ROM );
 	r_allowResize = ri.Cvar_Get( "r_allowResize", "0", CVAR_ARCHIVE | CVAR_LATCH );
 	r_centerWindow = ri.Cvar_Get( "r_centerWindow", "0", CVAR_ARCHIVE | CVAR_LATCH );
+	r_preferOpenGLES = ri.Cvar_Get( "r_preferOpenGLES", "-1", CVAR_ARCHIVE | CVAR_LATCH );
 
 	if( ri.Cvar_VariableIntegerValue( "com_abnormalExit" ) )
 	{
diff --git a/engine/code/sys/sys_main.c b/engine/code/sys/sys_main.c
index 0113920b..d7341806 100644
--- a/engine/code/sys/sys_main.c
+++ b/engine/code/sys/sys_main.c
@@ -31,6 +31,10 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #include <ctype.h>
 #include <errno.h>
 
+#ifdef __EMSCRIPTEN__
+#include <emscripten/emscripten.h>
+#endif
+
 #ifndef DEDICATED
 #ifdef USE_LOCAL_HEADERS
 #	include "SDL.h"
@@ -863,10 +867,14 @@ int main( int argc, char **argv )
 	signal( SIGTERM, Sys_SigHandler );
 	signal( SIGINT, Sys_SigHandler );
 
+#ifdef __EMSCRIPTEN__
+	emscripten_set_main_loop( Com_Frame, 0, 1 );
+#else
 	while( 1 )
 	{
 		Com_Frame( );
 	}
+#endif
 
 	return 0;
 }
diff --git a/engine/code/sys/sys_unix.c b/engine/code/sys/sys_unix.c
index 66b6fa17..db29e8f0 100644
--- a/engine/code/sys/sys_unix.c
+++ b/engine/code/sys/sys_unix.c
@@ -38,6 +38,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #include <fcntl.h>
 #include <fenv.h>
 #include <sys/wait.h>
+#include <time.h>
 
 qboolean stdinIsATTY;
 
@@ -548,11 +549,15 @@ void Sys_Sleep( int msec )
 	}
 	else
 	{
+		struct timespec req;
+
 		// With nothing to select() on, we can't wait indefinitely
 		if( msec < 0 )
 			msec = 10;
 
-		usleep( msec * 1000 );
+		req.tv_sec = msec/1000;
+		req.tv_nsec = (msec%1000)*1000000;
+		nanosleep(&req, NULL);
 	}
 }
 
diff --git a/engine/code/web/client-config.json b/engine/code/web/client-config.json
new file mode 100644
index 00000000..eddf35db
--- /dev/null
+++ b/engine/code/web/client-config.json
@@ -0,0 +1,47 @@
+{
+    "baseq3": {
+        "files": [
+            {"src": "baseq3/pak0.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak1.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak2.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak3.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak4.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak5.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak6.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak7.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/pak8.pk3", "dst": "/baseq3"},
+            {"src": "baseq3/vm/cgame.qvm", "dst": "/baseq3/vm"},
+            {"src": "baseq3/vm/qagame.qvm", "dst": "/baseq3/vm"},
+            {"src": "baseq3/vm/ui.qvm", "dst": "/baseq3/vm"}
+        ]
+    },
+    "missionpack": {
+        "files": [
+            {"src": "missionpack/pak0.pk3", "dst": "/missionpack"},
+            {"src": "missionpack/pak1.pk3", "dst": "/missionpack"},
+            {"src": "missionpack/pak2.pk3", "dst": "/missionpack"},
+            {"src": "missionpack/pak3.pk3", "dst": "/missionpack"},
+            {"src": "missionpack/vm/cgame.qvm", "dst": "/missionpack/vm"},
+            {"src": "missionpack/vm/qagame.qvm", "dst": "/missionpack/vm"},
+            {"src": "missionpack/vm/ui.qvm", "dst": "/missionpack/vm"}
+        ]
+    },
+    "demoq3": {
+        "_comment": "Copy baseq3/vm/*.qvm to demoq3/vm/ as the Quake 3 demo QVMs are not compatible. However the botfiles are not fully compatible with newer QVMs.",
+        "files": [
+            {"src": "demoq3/pak0.pk3", "dst": "/demoq3"},
+            {"src": "demoq3/vm/cgame.qvm", "dst": "/demoq3/vm"},
+            {"src": "demoq3/vm/qagame.qvm", "dst": "/demoq3/vm"},
+            {"src": "demoq3/vm/ui.qvm", "dst": "/demoq3/vm"}
+        ]
+    },
+    "tademo": {
+        "_comment": "Copy missionpack/vm/*.qvm to tademo/vm/ as the Team Arena demo QVMs are not compatible.",
+        "files": [
+            {"src": "tademo/pak0.pk3", "dst": "/tademo"},
+            {"src": "tademo/vm/cgame.qvm", "dst": "/tademo/vm"},
+            {"src": "tademo/vm/qagame.qvm", "dst": "/tademo/vm"},
+            {"src": "tademo/vm/ui.qvm", "dst": "/tademo/vm"}
+        ]
+    }
+}
diff --git a/engine/code/web/client.html b/engine/code/web/client.html
new file mode 100644
index 00000000..3a23ab92
--- /dev/null
+++ b/engine/code/web/client.html
@@ -0,0 +1,116 @@
+<!DOCTYPE html><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1">
+<title>__CLIENTBIN__ Emscripten demo</title>
+<style>
+html, body { margin: 0; padding: 0; width: 100%; height: 100%; overflow: hidden; background: rgb(0, 0, 0); display:flex; align-items: center; justify-content: center; }
+canvas { max-width: 100%; max-height: 100%; min-width: 100%; min-height: 100%; object-fit: contain; }
+</style>
+
+<canvas id=canvas></canvas>
+
+<script type=module>
+// These strings are set in the generated HTML file in the build directory.
+let CLIENTBIN = '__CLIENTBIN__';
+let BASEGAME = '__BASEGAME__';
+let EMSCRIPTEN_PRELOAD_FILE = Number('__EMSCRIPTEN_PRELOAD_FILE__');
+// Detect if it's not the generated HTML file.
+let clientHtmlFallback = (CLIENTBIN === '\_\_CLIENTBIN\_\_');
+
+// Path or URL containing the client engine .js, .wasm, and possibly .data.
+let enginePath = './';
+// Path or URL containing fs_game directories.
+let dataPath = './';
+// Path or URL for config file that specifies the files to load for each fs_game.
+let configFilename = `./${CLIENTBIN}-config.json`;
+
+// If displaying the unmodified HTML file, fallback to defaults.
+if (clientHtmlFallback) {
+    CLIENTBIN='ioquake3';
+    BASEGAME='baseq3';
+    EMSCRIPTEN_PRELOAD_FILE=0;
+    configFilename='./client-config.json';
+}
+
+if (window.location.protocol === 'file:') throw new Error(`Unfortunately browser security restrictions prevent loading wasm from a file: URL. This file must be loaded from a web server. The easiest way to do this is probably to use Python\'s built-in web server by running \`python3 -m http.server\` in the top level source directory and then navigate to http://localhost:8000/build/debug-emscripten-wasm32/${CLIENTBIN}.html`);
+
+// First set up the command line arguments and the Emscripten filesystem.
+const urlParams = new URLSearchParams(window.location.search);
+const com_basegame = urlParams.get('com_basegame') || BASEGAME;
+const fs_basegame = urlParams.get('fs_basegame') || '';
+const fs_game = urlParams.get('fs_game') || '';
+let generatedArguments = `
+    +set sv_pure 0
+    +set net_enabled 0
+    +set r_mode -2
+    +set com_basegame "${com_basegame}"
+    +set fs_basegame "${fs_basegame}"
+    +set fs_game "${fs_game}"
+`;
+// Note that unfortunately "+" needs to be encoded as "%2b" in URL query strings or it will be stripped by the browser.
+const queryArgs = urlParams.get('args');
+if (queryArgs) generatedArguments += ` ${queryArgs} `;
+
+// If displaying the unmodified HTML file, the engine and data are probably located in a different directory.
+if (clientHtmlFallback) {
+    // If buildPath is not specified, try to find a build in one of a few default paths.
+    let buildPath = urlParams.get('buildPath');
+    if (buildPath && !buildPath.endsWith('/')) buildPath += '/';
+    const buildPaths = buildPath ? [buildPath] : ['../../build/debug-emscripten-wasm32/', '../../build/release-emscripten-wasm32/', './'];
+    const scriptPaths = buildPaths.map(buildPath => buildPath + `${CLIENTBIN}_opengl2.wasm32.js`);
+    const scriptResponses = await Promise.all(scriptPaths.map(p => fetch(p, {method: 'HEAD'})));
+    const validBuilds = scriptResponses.filter(r => r.ok).length;
+    const goodURL = (newPath) => {
+        const url = new URL(window.location);
+        url.searchParams.set('buildPath', newPath);
+        return url.toString().replace(/%2f/gi, '/');
+    };
+    if (validBuilds === 0) throw new Error(`Didn't find any wasm builds. Run \`emmake make debug\` to build one, or use the buildPath query parameter to specify a directory containing ${CLIENTBIN}_opengl2.wasm32.[js,wasm,data], e.g. ${goodURL('../../build/debug-emscripten-wasm32/')}`);
+    if (validBuilds > 1) throw new Error(`Found multiple valid builds at the following paths: [${buildPaths.filter((path, i)=>scriptResponses[i].ok)}]. Please specify which one to run by adding a buildPath query parameter to the URL, e.g. ${goodURL(buildPaths.filter((path, i)=>scriptResponses[i].ok)[0])}`);
+    const buildIndex = scriptResponses.findIndex(r => r.ok);
+
+    enginePath = buildPaths[buildIndex];
+    dataPath = buildPaths[buildIndex];
+}
+
+const dataURL = new URL(dataPath, location.origin + location.pathname);
+
+const configPromise = ( EMSCRIPTEN_PRELOAD_FILE === 1 ) ? Promise.resolve({[BASEGAME]: {files: []}})
+  : fetch(configFilename).then(r => r.ok ? r.json() : { /* empty config */ });
+
+const ioquake3 = (await import(enginePath + `${CLIENTBIN}_opengl2.wasm32.js`)).default;
+ioquake3({
+    canvas: canvas,
+    arguments: generatedArguments.trim().split(/\s+/),
+    locateFile: (file) => enginePath + file,
+    preRun: [async (module) => {
+        module.addRunDependency('setup-ioq3-filesystem');
+        try {
+            const config = await configPromise;
+            const gamedirs = [com_basegame,fs_basegame,fs_game];
+            for (let g = 0; g < gamedirs.length; g++) {
+                const gamedir = gamedirs[g];
+                if (gamedir === '') {
+                    continue;
+                }
+                if (config[gamedir] === null
+                 || config[gamedir].files === null) {
+                    console.warn(`Game directory '${gamedir}' cannot be used. It must have files listed in ${configFilename}.`);
+                    continue;
+                }
+                const files = config[gamedir].files;
+                const fetches = files.map(file => fetch(new URL(file.src, dataURL)));
+                for (let i = 0; i < files.length; i++) {
+                    const response = await fetches[i];
+                    if (!response.ok) continue;
+                    const data = await response.arrayBuffer();
+                    let name = files[i].src.match(/[^/]+$/)[0];
+                    let dir = files[i].dst;
+                    module.FS.mkdirTree(dir);
+                    module.FS.writeFile(`${dir}/${name}`, new Uint8Array(data));
+                }
+            }
+        } finally {
+            module.removeRunDependency('setup-ioq3-filesystem');
+        }
+    }],
+});
+</script>
diff --git a/engine/docs/README.md b/engine/docs/README.md
index ce2999cb..bbaede21 100644
--- a/engine/docs/README.md
+++ b/engine/docs/README.md
@@ -31,6 +31,7 @@ Some of the major features currently implemented are:
   * Multiuser support on Windows systems (user specific game data
     is stored in "%APPDATA%\Quake3")
   * PNG support
+  * Web support via Emscripten
   * Many, many bug fixes
 
 The map editor and associated compiling tools are not included. We suggest you
@@ -98,6 +99,20 @@ For macOS, building a Universal Binary 2 (macOS 10.9+, arm64, x86_64)
   4. Copy the resulting ioquake3.app in /build/release-darwin-universal2
      to your /Applications/ioquake3 folder.
 
+For Web, building with Emscripten
+  1. Follow the installation instructions for the Emscripten SDK including
+     setting up the environment with emsdk_env.
+  2. Run `emmake make debug` (or release).
+  3. Copy or symlink your baseq3 pk3 files into the `build/debug-emscripten-wasm32/baseq3`
+     directory so they can be loaded at run-time. Only game files listed in
+     `client-config.json` will be loaded.
+  4. Start a web server serving this directory. `python3 -m http.server`
+     is an easy default that you may already have installed.
+  5. Open `http://localhost:8000/build/debug-emscripten-wasm32/ioquake3.html`
+     in a web browser. Open the developer console to see errors and warnings.
+  6. Debugging the C code is possible using a Chrome extension. For details
+     see https://developer.chrome.com/blog/wasm-debugging-2020
+
 Installation, for *nix
   1. Set the COPYDIR variable in the shell to be where you installed Quake 3
      to. By default it will be /usr/local/games/quake3 if you haven't set it.
@@ -115,6 +130,8 @@ The following variables may be set, either on the command line or in
 Makefile.local:
 
 ```
+  DEPEND_MAKEFILE      - set to 0 to disable rebuilding all targets when
+                         the Makefile or Makefile.local is changed
   CFLAGS               - use this for custom CFLAGS
   V                    - set to show cc command line when building
   DEFAULT_BASEDIR      - extra path to search for baseq3 and such
@@ -128,6 +145,8 @@ Makefile.local:
   SERVERBIN            - rename 'ioq3ded' server binary
   CLIENTBIN            - rename 'ioquake3' client binary
   USE_RENDERER_DLOPEN  - build and use the renderer in a library
+  BUILD_RENDERER_OPENGL1 build the opengl1 client / renderer library
+  BUILD_RENDERER_OPENGL2 build the opengl2 client / renderer library
   USE_YACC             - use yacc to update code/tools/lcc/lburg/gram.c
   BASEGAME             - rename 'baseq3'
   BASEGAME_CFLAGS      - custom CFLAGS for basegame
@@ -155,11 +174,31 @@ Makefile.local:
   DEBUG_CFLAGS         - C compiler flags to use for building debug version
   COPYDIR              - the target installation directory
   TEMPDIR              - specify user defined directory for temp files
+  EMSCRIPTEN_PRELOAD_FILE - set to 1 to package 'baseq3' (BASEGAME) directory
+                            containing pk3s and loose files as a single
+                            .data file that is loaded instead of listing
+                            individual files in client-config.json
 ```
 
 The defaults for these variables differ depending on the target platform.
 
 
+# OpenGL ES support
+
+The opengl2 renderer (the default) supports OpenGL ES 2+. Though there
+are many missing features and the performance may not be sufficient for
+embedded System-on-a-Chip and mobile platforms.
+
+The opengl1 renderer does not have OpenGL ES support.
+
+The opengl2 renderer will try both OpenGL and OpenGL ES APIs to find one that
+works. The `r_preferOpenGLES` cvar controls which API to try first.
+Set it to -1 for auto (default), 0 for OpenGL, and 1 for OpenGL ES. It should be
+set using command line arguments:
+
+    ioquake3 +set cl_renderer opengl2 +set r_preferOpenGLES 1
+
+
 # Console
 
 ## New cvars
diff --git a/engine/docs/opengl2-readme.md b/engine/docs/opengl2-readme.md
index ee85c02c..c798d89c 100644
--- a/engine/docs/opengl2-readme.md
+++ b/engine/docs/opengl2-readme.md
@@ -63,6 +63,14 @@ For Win32:
   CVARS
 -------------------------------------------------------------------------------
 
+Cvars for API:
+
+* `r_preferOpenGLES`                - This sets the preference for using OpenGL or OpenGL ES 2.
+                                   Many features are not supported when using OpenGL ES such as sun shadows and HDR.
+                                     1 - Prefer OpenGL ES 2+.
+                                     0 - Prefer desktop OpenGL.
+                                     -1 - Automatically pick (default).
+
 Cvars for simple rendering features:
 
 * `r_ext_compressed_textures`       - Automatically compress textures.