diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 000000000..5ce158013
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+*.cpp text
diff --git a/.gitignore b/.gitignore
index 849ed7b2a..b3d0eb257 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,3 +40,4 @@
 /zlib/x64/
 /build_vc2013_64bit
 /build_vc2015
+/build_cmake
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 799bf6dd4..3ef99327b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -762,6 +762,7 @@ file( GLOB HEADER_FILES
 	gl/models/*.h
 	gl/renderer/*.h
 	gl/scene/*.h
+	gl/stereo3d/*.h
 	gl/shaders/*.h
 	gl/system/*.h
 	gl/textures/*.h
@@ -1120,6 +1121,11 @@ add_executable( zdoom WIN32 MACOSX_BUNDLE
 	gl/scene/gl_walls_draw.cpp
 	gl/scene/gl_vertex.cpp
 	gl/scene/gl_spritelight.cpp
+	gl/stereo3d/gl_stereo3d.cpp
+	gl/stereo3d/gl_stereo_cvars.cpp
+	gl/stereo3d/gl_stereo_leftright.cpp
+	gl/stereo3d/scoped_view_shifter.cpp
+	gl/stereo3d/gl_anaglyph.cpp
 	gl/dynlights/gl_dynlight.cpp
 	gl/dynlights/gl_glow.cpp
 	gl/dynlights/gl_dynlight1.cpp
@@ -1371,6 +1377,7 @@ source_group("OpenGL Renderer\\HQ Resize Assembly version" REGULAR_EXPRESSION "^
 source_group("OpenGL Renderer\\Models" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/models/.+")
 source_group("OpenGL Renderer\\Renderer" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/renderer/.+")
 source_group("OpenGL Renderer\\Scene" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/scene/.+")
+source_group("OpenGL Renderer\\Stereo3D" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/stereo3d/.+")
 source_group("OpenGL Renderer\\Shaders" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/shaders/.+")
 source_group("OpenGL Renderer\\System" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/system/.+")
 source_group("OpenGL Renderer\\Textures" REGULAR_EXPRESSION "^${CMAKE_CURRENT_SOURCE_DIR}/gl/textures/.+")
diff --git a/src/gl/renderer/gl_renderer.h b/src/gl/renderer/gl_renderer.h
index 534745869..3374c904a 100644
--- a/src/gl/renderer/gl_renderer.h
+++ b/src/gl/renderer/gl_renderer.h
@@ -5,6 +5,7 @@
 #include "v_video.h"
 #include "vectors.h"
 #include "r_renderer.h"
+#include "gl/data/gl_matrix.h"
 
 struct particle_t;
 class FCanvasTexture;
@@ -120,6 +121,7 @@ public:
 	void Flush() {}
 
 	void SetProjection(float fov, float ratio, float fovratio);
+	void SetProjection(FLOATTYPE matrix[4][4]); // raw matrix input from stereo 3d modes
 	void SetViewMatrix(fixed_t viewx, fixed_t viewy, fixed_t viewz, bool mirror, bool planemirror);
 	void ProcessScene(bool toscreen = false);
 
diff --git a/src/gl/scene/gl_drawinfo.cpp b/src/gl/scene/gl_drawinfo.cpp
index 08eb3b26d..4dba1a2a0 100644
--- a/src/gl/scene/gl_drawinfo.cpp
+++ b/src/gl/scene/gl_drawinfo.cpp
@@ -56,6 +56,7 @@
 #include "gl/utility/gl_clock.h"
 #include "gl/utility/gl_templates.h"
 #include "gl/shaders/gl_shader.h"
+#include "gl/stereo3d/scoped_color_mask.h"
 
 FDrawInfo * gl_drawinfo;
 
@@ -1009,31 +1010,33 @@ void FDrawInfo::SetupFloodStencil(wallseg * ws)
 	int recursion = GLPortal::GetRecursion();
 
 	// Create stencil 
-	glStencilFunc(GL_EQUAL,recursion,~0);		// create stencil
-	glStencilOp(GL_KEEP,GL_KEEP,GL_INCR);		// increment stencil of valid pixels
-	glColorMask(0,0,0,0);						// don't write to the graphics buffer
-	gl_RenderState.EnableTexture(false);
-	gl_RenderState.ResetColor();
-	glEnable(GL_DEPTH_TEST);
-	glDepthMask(true);
+	glStencilFunc(GL_EQUAL, recursion, ~0);		// create stencil
+	glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);		// increment stencil of valid pixels
+	{
+		// Use revertible color mask, to avoid stomping on anaglyph 3D state
+		ScopedColorMask colorMask(0, 0, 0, 0); // glColorMask(0, 0, 0, 0);						// don't write to the graphics buffer
+		gl_RenderState.EnableTexture(false);
+		gl_RenderState.ResetColor();
+		glEnable(GL_DEPTH_TEST);
+		glDepthMask(true);
 
-	gl_RenderState.Apply();
-	FFlatVertex *ptr = GLRenderer->mVBO->GetBuffer();
-	ptr->Set(ws->x1, ws->z1, ws->y1, 0, 0);
-	ptr++;
-	ptr->Set(ws->x1, ws->z2, ws->y1, 0, 0);
-	ptr++;
-	ptr->Set(ws->x2, ws->z2, ws->y2, 0, 0);
-	ptr++;
-	ptr->Set(ws->x2, ws->z1, ws->y2, 0, 0);
-	ptr++;
-	GLRenderer->mVBO->RenderCurrent(ptr, GL_TRIANGLE_FAN);
+		gl_RenderState.Apply();
+		FFlatVertex *ptr = GLRenderer->mVBO->GetBuffer();
+		ptr->Set(ws->x1, ws->z1, ws->y1, 0, 0);
+		ptr++;
+		ptr->Set(ws->x1, ws->z2, ws->y1, 0, 0);
+		ptr++;
+		ptr->Set(ws->x2, ws->z2, ws->y2, 0, 0);
+		ptr++;
+		ptr->Set(ws->x2, ws->z1, ws->y2, 0, 0);
+		ptr++;
+		GLRenderer->mVBO->RenderCurrent(ptr, GL_TRIANGLE_FAN);
 
 
-	glStencilFunc(GL_EQUAL,recursion+1,~0);		// draw sky into stencil
-	glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);		// this stage doesn't modify the stencil
+		glStencilFunc(GL_EQUAL, recursion + 1, ~0);		// draw sky into stencil
+		glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);		// this stage doesn't modify the stencil
 
-	glColorMask(1,1,1,1);						// don't write to the graphics buffer
+	} // glColorMask(1, 1, 1, 1);						// don't write to the graphics buffer
 	gl_RenderState.EnableTexture(true);
 	glDisable(GL_DEPTH_TEST);
 	glDepthMask(false);
@@ -1045,26 +1048,28 @@ void FDrawInfo::ClearFloodStencil(wallseg * ws)
 
 	glStencilOp(GL_KEEP,GL_KEEP,GL_DECR);
 	gl_RenderState.EnableTexture(false);
-	glColorMask(0,0,0,0);						// don't write to the graphics buffer
-	gl_RenderState.ResetColor();
+	{
+		// Use revertible color mask, to avoid stomping on anaglyph 3D state
+		ScopedColorMask colorMask(0, 0, 0, 0); // glColorMask(0,0,0,0);						// don't write to the graphics buffer
+		gl_RenderState.ResetColor();
 
-	gl_RenderState.Apply();
-	FFlatVertex *ptr = GLRenderer->mVBO->GetBuffer();
-	ptr->Set(ws->x1, ws->z1, ws->y1, 0, 0);
-	ptr++;
-	ptr->Set(ws->x1, ws->z2, ws->y1, 0, 0);
-	ptr++;
-	ptr->Set(ws->x2, ws->z2, ws->y2, 0, 0);
-	ptr++;
-	ptr->Set(ws->x2, ws->z1, ws->y2, 0, 0);
-	ptr++;
-	GLRenderer->mVBO->RenderCurrent(ptr, GL_TRIANGLE_FAN);
+		gl_RenderState.Apply();
+		FFlatVertex *ptr = GLRenderer->mVBO->GetBuffer();
+		ptr->Set(ws->x1, ws->z1, ws->y1, 0, 0);
+		ptr++;
+		ptr->Set(ws->x1, ws->z2, ws->y1, 0, 0);
+		ptr++;
+		ptr->Set(ws->x2, ws->z2, ws->y2, 0, 0);
+		ptr++;
+		ptr->Set(ws->x2, ws->z1, ws->y2, 0, 0);
+		ptr++;
+		GLRenderer->mVBO->RenderCurrent(ptr, GL_TRIANGLE_FAN);
 
-	// restore old stencil op.
-	glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);
-	glStencilFunc(GL_EQUAL,recursion,~0);
-	gl_RenderState.EnableTexture(true);
-	glColorMask(1,1,1,1);
+		// restore old stencil op.
+		glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
+		glStencilFunc(GL_EQUAL, recursion, ~0);
+		gl_RenderState.EnableTexture(true);
+	} // glColorMask(1, 1, 1, 1);
 	glEnable(GL_DEPTH_TEST);
 	glDepthMask(true);
 }
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 54bc9b540..7ff82db4c 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -59,6 +59,7 @@
 #include "gl/scene/gl_drawinfo.h"
 #include "gl/scene/gl_portal.h"
 #include "gl/shaders/gl_shader.h"
+#include "gl/stereo3d/scoped_color_mask.h"
 #include "gl/textures/gl_material.h"
 #include "gl/utility/gl_clock.h"
 #include "gl/utility/gl_templates.h"
@@ -197,7 +198,7 @@ bool GLPortal::Start(bool usestencil, bool doquery)
 		// Create stencil 
 		glStencilFunc(GL_EQUAL,recursion,~0);		// create stencil
 		glStencilOp(GL_KEEP,GL_KEEP,GL_INCR);		// increment stencil of valid pixels
-		glColorMask(0,0,0,0);						// don't write to the graphics buffer
+		// glColorMask(0,0,0,0);						// don't write to the graphics buffer
 		gl_RenderState.SetEffect(EFF_STENCIL);
 		gl_RenderState.EnableTexture(false);
 		gl_RenderState.ResetColor();
@@ -206,34 +207,36 @@ bool GLPortal::Start(bool usestencil, bool doquery)
 
 		if (NeedDepthBuffer())
 		{
-			glDepthMask(false);							// don't write to Z-buffer!
-			if (!NeedDepthBuffer()) doquery = false;		// too much overhead and nothing to gain.
-			else if (gl_noquery) doquery = false;
-			
-			// If occlusion query is supported let's use it to avoid rendering portals that aren't visible
-			if (!QueryObject) glGenQueries(1, &QueryObject);
-			if (QueryObject) 
 			{
-				glBeginQuery(GL_SAMPLES_PASSED, QueryObject);
-			}
-			else doquery = false;	// some kind of error happened
+				ScopedColorMask colorMask(0, 0, 0, 0);
+				glDepthMask(false);							// don't write to Z-buffer!
+				if (!NeedDepthBuffer()) doquery = false;		// too much overhead and nothing to gain.
+				else if (gl_noquery) doquery = false;
 
-			DrawPortalStencil();
+				// If occlusion query is supported let's use it to avoid rendering portals that aren't visible
+				if (!QueryObject) glGenQueries(1, &QueryObject);
+				if (QueryObject)
+				{
+					glBeginQuery(GL_SAMPLES_PASSED, QueryObject);
+				}
+				else doquery = false;	// some kind of error happened
 
-			glEndQuery(GL_SAMPLES_PASSED);
+				DrawPortalStencil();
 
-			// Clear Z-buffer
-			glStencilFunc(GL_EQUAL,recursion+1,~0);		// draw sky into stencil
-			glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);		// this stage doesn't modify the stencil
-			glDepthMask(true);							// enable z-buffer again
-			glDepthRange(1,1);
-			glDepthFunc(GL_ALWAYS);
-			DrawPortalStencil();
+				glEndQuery(GL_SAMPLES_PASSED);
 
-			// set normal drawing mode
-			gl_RenderState.EnableTexture(true);
-			glDepthFunc(GL_LESS);
-			glColorMask(1,1,1,1);
+				// Clear Z-buffer
+				glStencilFunc(GL_EQUAL, recursion + 1, ~0);		// draw sky into stencil
+				glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);		// this stage doesn't modify the stencil
+				glDepthMask(true);							// enable z-buffer again
+				glDepthRange(1, 1);
+				glDepthFunc(GL_ALWAYS);
+				DrawPortalStencil();
+
+				// set normal drawing mode
+				gl_RenderState.EnableTexture(true);
+				glDepthFunc(GL_LESS);
+			} // glColorMask(1, 1, 1, 1);
 			gl_RenderState.SetEffect(EFF_NONE);
 			glDepthRange(0, 1);
 
@@ -258,12 +261,13 @@ bool GLPortal::Start(bool usestencil, bool doquery)
 			// than the benefit.
 			// Note: We must draw the stencil with z-write enabled here because there is no second pass!
 
+			ScopedColorMask colorMask(0, 0, 0, 0);
 			glDepthMask(true);
 			DrawPortalStencil();
 			glStencilFunc(GL_EQUAL,recursion+1,~0);		// draw sky into stencil
 			glStencilOp(GL_KEEP,GL_KEEP,GL_KEEP);		// this stage doesn't modify the stencil
 			gl_RenderState.EnableTexture(true);
-			glColorMask(1,1,1,1);
+			// glColorMask(1,1,1,1);
 			gl_RenderState.SetEffect(EFF_NONE);
 			glDisable(GL_DEPTH_TEST);
 			glDepthMask(false);							// don't write to Z-buffer!
@@ -369,38 +373,39 @@ void GLPortal::End(bool usestencil)
 		viewangle=savedviewangle;
 		GLRenderer->mViewActor=savedviewactor;
 		in_area=savedviewarea;
-		GLRenderer->SetupView(viewx, viewy, viewz, viewangle, !!(MirrorFlag&1), !!(PlaneMirrorFlag&1));
+		GLRenderer->SetupView(viewx, viewy, viewz, viewangle, !!(MirrorFlag & 1), !!(PlaneMirrorFlag & 1));
 
-		glColorMask(0,0,0,0);						// no graphics
-		gl_RenderState.SetEffect(EFF_NONE);
-		gl_RenderState.ResetColor();
-		gl_RenderState.EnableTexture(false);
-		gl_RenderState.Apply();
-
-		if (needdepth) 
 		{
-			// first step: reset the depth buffer to max. depth
-			glDepthRange(1,1);							// always
-			glDepthFunc(GL_ALWAYS);						// write the farthest depth value
+			ScopedColorMask colorMask(0, 0, 0, 0); //  glColorMask(0, 0, 0, 0);						// no graphics
+			gl_RenderState.SetEffect(EFF_NONE);
+			gl_RenderState.ResetColor();
+			gl_RenderState.EnableTexture(false);
+			gl_RenderState.Apply();
+
+			if (needdepth)
+			{
+				// first step: reset the depth buffer to max. depth
+				glDepthRange(1, 1);							// always
+				glDepthFunc(GL_ALWAYS);						// write the farthest depth value
+				DrawPortalStencil();
+			}
+			else
+			{
+				glEnable(GL_DEPTH_TEST);
+			}
+
+			// second step: restore the depth buffer to the previous values and reset the stencil
+			glDepthFunc(GL_LEQUAL);
+			glDepthRange(0, 1);
+			glStencilOp(GL_KEEP, GL_KEEP, GL_DECR);
+			glStencilFunc(GL_EQUAL, recursion, ~0);		// draw sky into stencil
 			DrawPortalStencil();
-		}
-		else
-		{
-			glEnable(GL_DEPTH_TEST);
-		}
-		
-		// second step: restore the depth buffer to the previous values and reset the stencil
-		glDepthFunc(GL_LEQUAL);
-		glDepthRange(0,1);
-		glStencilOp(GL_KEEP,GL_KEEP,GL_DECR);
-		glStencilFunc(GL_EQUAL,recursion,~0);		// draw sky into stencil
-		DrawPortalStencil();
-		glDepthFunc(GL_LESS);
+			glDepthFunc(GL_LESS);
 
 
-		gl_RenderState.EnableTexture(true);
-		gl_RenderState.SetEffect(EFF_NONE);
-		glColorMask(1, 1, 1, 1);
+			gl_RenderState.EnableTexture(true);
+			gl_RenderState.SetEffect(EFF_NONE);
+		} // glColorMask(1, 1, 1, 1);
 		recursion--;
 
 		// restore old stencil op.
@@ -433,14 +438,15 @@ void GLPortal::End(bool usestencil)
 
 		gl_RenderState.ResetColor();
 		glDepthFunc(GL_LEQUAL);
-		glDepthRange(0,1);
-		glColorMask(0,0,0,0);						// no graphics
-		gl_RenderState.SetEffect(EFF_STENCIL);
-		gl_RenderState.EnableTexture(false);
-		DrawPortalStencil();
-		gl_RenderState.SetEffect(EFF_NONE);
-		gl_RenderState.EnableTexture(true);
-		glColorMask(1,1,1,1);
+		glDepthRange(0, 1);
+		{
+			ScopedColorMask colorMask(0, 0, 0, 0); // glColorMask(0,0,0,0);						// no graphics
+			gl_RenderState.SetEffect(EFF_STENCIL);
+			gl_RenderState.EnableTexture(false);
+			DrawPortalStencil();
+			gl_RenderState.SetEffect(EFF_NONE);
+			gl_RenderState.EnableTexture(true);
+		} // glColorMask(1, 1, 1, 1);
 		glDepthFunc(GL_LESS);
 	}
 	PortalAll.Unclock();
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 3d716e215..618c285c0 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -71,6 +71,8 @@
 #include "gl/scene/gl_drawinfo.h"
 #include "gl/scene/gl_portal.h"
 #include "gl/shaders/gl_shader.h"
+#include "gl/stereo3d/gl_stereo3d.h"
+#include "gl/stereo3d/scoped_view_shifter.h"
 #include "gl/textures/gl_material.h"
 #include "gl/utility/gl_clock.h"
 #include "gl/utility/gl_convert.h"
@@ -254,6 +256,13 @@ void FGLRenderer::SetProjection(float fov, float ratio, float fovratio)
 	gl_RenderState.Set2DMode(false);
 }
 
+// raw matrix input from stereo 3d modes
+void FGLRenderer::SetProjection(FLOATTYPE matrix[4][4])
+{
+	gl_RenderState.mProjectionMatrix.loadMatrix(&matrix[0][0]);
+	gl_RenderState.Set2DMode(false);
+}
+
 //-----------------------------------------------------------------------------
 //
 // Setup the modelview matrix
@@ -802,18 +811,36 @@ sector_t * FGLRenderer::RenderViewpoint (AActor * camera, GL_IRECT * bounds, flo
 
 	retval = viewsector;
 
-	SetViewport(bounds);
-	mCurrentFoV = fov;
-	SetProjection(fov, ratio, fovratio);	// switch to perspective mode and set up clipper
-	SetViewAngle(viewangle);
-	SetViewMatrix(viewx, viewy, viewz, false, false);
-	gl_RenderState.ApplyMatrices();
+	// Render (potentially) multiple views for stereo 3d
+	FLOATTYPE projectionMatrix[4][4];
+	float viewShift[3];
+	const s3d::Stereo3DMode& stereo3dMode = s3d::Stereo3DMode::getCurrentMode();
+	stereo3dMode.SetUp();
+	s3d::Stereo3DMode::const_iterator eye;
+	for (eye = stereo3dMode.begin(); eye != stereo3dMode.end(); ++eye)
+	{
+		(*eye)->SetUp();
+		// TODO: stereo specific viewport - needed when implementing side-by-side modes etc.
+		SetViewport(bounds);
+		mCurrentFoV = fov;
+		// Stereo mode specific perspective projection
+		(*eye)->GetProjection(fov, ratio, fovratio, projectionMatrix);
+		SetProjection(projectionMatrix);
+		SetProjection(fov, ratio, fovratio);	// switch to perspective mode and set up clipper
+		SetViewAngle(viewangle);
+		// Stereo mode specific viewpoint adjustment - temporarily shifts global viewx, viewy, viewz
+		(*eye)->GetViewShift(GLRenderer->mAngles.Yaw, viewShift);
+		s3d::ScopedViewShifter viewShifter(viewShift);
+		SetViewMatrix(viewx, viewy, viewz, false, false);
+		gl_RenderState.ApplyMatrices();
 
-	clipper.Clear();
-	angle_t a1 = FrustumAngle();
-	clipper.SafeAddClipRangeRealAngles(viewangle+a1, viewangle-a1);
+		clipper.Clear();
+		angle_t a1 = FrustumAngle();
+		clipper.SafeAddClipRangeRealAngles(viewangle + a1, viewangle - a1);
 
-	ProcessScene(toscreen);
+		ProcessScene(toscreen);
+	}
+	stereo3dMode.TearDown();
 
 	gl_frameCount++;	// This counter must be increased right before the interpolations are restored.
 	interpolator.RestoreInterpolations ();
diff --git a/src/gl/stereo3d/gl_anaglyph.cpp b/src/gl/stereo3d/gl_anaglyph.cpp
index ff3926cfc..e8be92882 100644
--- a/src/gl/stereo3d/gl_anaglyph.cpp
+++ b/src/gl/stereo3d/gl_anaglyph.cpp
@@ -11,7 +11,7 @@ MaskAnaglyph::MaskAnaglyph(const ColorMask& leftColorMask, double ipdMeters)
 
 
 /* static */
-const GreenMagenta& GreenMagenta::getInstance(float ipd)
+const GreenMagenta& GreenMagenta::getInstance(FLOATTYPE ipd)
 {
 	static GreenMagenta instance(ipd);
 	return instance;
@@ -19,7 +19,7 @@ const GreenMagenta& GreenMagenta::getInstance(float ipd)
 
 
 /* static */
-const RedCyan& RedCyan::getInstance(float ipd)
+const RedCyan& RedCyan::getInstance(FLOATTYPE ipd)
 {
 	static RedCyan instance(ipd);
 	return instance;
diff --git a/src/gl/stereo3d/gl_anaglyph.h b/src/gl/stereo3d/gl_anaglyph.h
index c95d04205..4be6da99e 100644
--- a/src/gl/stereo3d/gl_anaglyph.h
+++ b/src/gl/stereo3d/gl_anaglyph.h
@@ -3,6 +3,7 @@
 
 #include "gl_stereo3d.h"
 #include "gl_stereo_leftright.h"
+#include "gl/system/gl_system.h"
 
 
 namespace s3d {
diff --git a/src/gl/stereo3d/gl_stereo3d.cpp b/src/gl/stereo3d/gl_stereo3d.cpp
index 74b36a0fb..e053266b7 100644
--- a/src/gl/stereo3d/gl_stereo3d.cpp
+++ b/src/gl/stereo3d/gl_stereo3d.cpp
@@ -6,24 +6,23 @@ namespace s3d {
 
 
 /* virtual */
-void EyePose::GetProjection(float fov, float aspectRatio, float fovRatio, GLdouble m[4][4]) const
+void EyePose::GetProjection(FLOATTYPE fov, FLOATTYPE aspectRatio, FLOATTYPE fovRatio, FLOATTYPE m[4][4]) const
 {
 	// Lifted from gl_scene.cpp FGLRenderer::SetProjection()
-	float fovy = 2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovRatio));
-	const double zNear = 5.0;
-	const double zFar = 65536.0;
+	double fovy = 2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovRatio));
+	const FLOATTYPE zNear = 5.0;
+	const FLOATTYPE zFar = 65536.0;
 
-	double sine, cotangent, deltaZ;
 	double radians = fovy / 2 * M_PI / 180;
 
-	deltaZ = zFar - zNear;
-	sine = sin(radians);
+	FLOATTYPE deltaZ = zFar - zNear;
+	double sine = sin(radians);
 	if ((deltaZ == 0) || (sine == 0) || (aspectRatio == 0)) {
 		return;
 	}
-	cotangent = cos(radians) / sine;
+	FLOATTYPE cotangent = FLOATTYPE(cos(radians) / sine);
 
-	memset(m, 0, 16*sizeof(GLdouble));
+	memset(m, 0, 16*sizeof(FLOATTYPE));
 	m[0][0] = cotangent / aspectRatio;
 	m[1][1] = cotangent;
 	m[2][2] = -(zFar + zNear) / deltaZ;
@@ -40,7 +39,7 @@ Viewport EyePose::GetViewport(const Viewport& fullViewport) const
 
 
 /* virtual */
-void EyePose::GetViewShift(float yaw, float outViewShift[3]) const
+void EyePose::GetViewShift(FLOATTYPE yaw, FLOATTYPE outViewShift[3]) const
 {
 	// pass-through for Mono view
 	outViewShift[0] = 0;
diff --git a/src/gl/stereo3d/gl_stereo3d.h b/src/gl/stereo3d/gl_stereo3d.h
index ddbaafaf2..6421b2a9e 100644
--- a/src/gl/stereo3d/gl_stereo3d.h
+++ b/src/gl/stereo3d/gl_stereo3d.h
@@ -2,7 +2,7 @@
 #define GL_STEREO3D_H_
 
 #include <vector>
-#include "gl/system/gl_system.h"
+#include "gl/data/gl_matrix.h"
 
 
 /* stereoscopic 3D API */
@@ -24,9 +24,9 @@ class EyePose
 public:
 	EyePose() {}
 	virtual ~EyePose() {}
-	virtual void GetProjection(float fov, float aspectRatio, float fovRatio, GLdouble outMatrix[4][4]) const;
+	virtual void GetProjection(FLOATTYPE fov, FLOATTYPE aspectRatio, FLOATTYPE fovRatio, FLOATTYPE outMatrix[4][4]) const;
 	virtual Viewport GetViewport(const Viewport& fullViewport) const;
-	virtual void GetViewShift(float yaw, float outViewShift[3]) const;
+	virtual void GetViewShift(FLOATTYPE yaw, FLOATTYPE outViewShift[3]) const;
 	virtual void SetUp() const {};
 	virtual void TearDown() const {};
 };
diff --git a/src/gl/stereo3d/gl_stereo_cvars.cpp b/src/gl/stereo3d/gl_stereo_cvars.cpp
index e9d115080..b91a47daa 100644
--- a/src/gl/stereo3d/gl_stereo_cvars.cpp
+++ b/src/gl/stereo3d/gl_stereo_cvars.cpp
@@ -33,10 +33,11 @@ const Stereo3DMode& Stereo3DMode::getCurrentMode()
 	case 2:
 		setCurrentMode(RedCyan::getInstance(vr_ipd));
 		break;
-	case 3:
+	// TODO: missing indices 3, 4 for not-yet-implemented side-by-side modes, to match values from GZ3Doom
+	case 5:
 		setCurrentMode(LeftEyeView::getInstance(vr_ipd));
 		break;
-	case 4:
+	case 6:
 		setCurrentMode(RightEyeView::getInstance(vr_ipd));
 		break;
 	case 0:
diff --git a/src/gl/stereo3d/gl_stereo_leftright.cpp b/src/gl/stereo3d/gl_stereo_leftright.cpp
index fd1f97729..58cbb086e 100644
--- a/src/gl/stereo3d/gl_stereo_leftright.cpp
+++ b/src/gl/stereo3d/gl_stereo_leftright.cpp
@@ -11,10 +11,10 @@ namespace s3d {
 
 
 /* virtual */
-void ShiftedEyePose::GetProjection(float fov, float aspectRatio, float fovRatio, GLdouble m[4][4]) const
+void ShiftedEyePose::GetProjection(FLOATTYPE fov, FLOATTYPE aspectRatio, FLOATTYPE fovRatio, FLOATTYPE m[4][4]) const
 {
 	// Lifted from gl_scene.cpp FGLRenderer::SetProjection()
-	float fovy = 2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovRatio));
+	FLOATTYPE fovy = 2 * RAD2DEG(atan(tan(DEG2RAD(fov) / 2) / fovRatio));
 	double zNear = 5.0;
 	double zFar = 65536.0;
 
@@ -33,7 +33,7 @@ void ShiftedEyePose::GetProjection(float fov, float aspectRatio, float fovRatio,
 	double top = fH;
 	double deltaZ = zFar - zNear;
 
-	memset(m, 0, 16 * sizeof(GLdouble)); // set all elements to zero, cleverly
+	memset(m, 0, 16 * sizeof(FLOATTYPE)); // set all elements to zero, cleverly
 
 	// https://www.opengl.org/sdk/docs/man2/xhtml/glFrustum.xml
 	m[0][0] = 2 * zNear / (right - left);
@@ -48,10 +48,10 @@ void ShiftedEyePose::GetProjection(float fov, float aspectRatio, float fovRatio,
 
 
 /* virtual */
-void ShiftedEyePose::GetViewShift(float yaw, float outViewShift[3]) const
+void ShiftedEyePose::GetViewShift(FLOATTYPE yaw, FLOATTYPE outViewShift[3]) const
 {
-	float dx = cos(DEG2RAD(yaw)) * vr_hunits_per_meter * shift;
-	float dy = sin(DEG2RAD(yaw)) * vr_hunits_per_meter * shift;
+	FLOATTYPE dx = cos(DEG2RAD(yaw)) * vr_hunits_per_meter * shift;
+	FLOATTYPE dy = sin(DEG2RAD(yaw)) * vr_hunits_per_meter * shift;
 	outViewShift[0] = dx;
 	outViewShift[1] = dy;
 	outViewShift[2] = 0;
@@ -59,7 +59,7 @@ void ShiftedEyePose::GetViewShift(float yaw, float outViewShift[3]) const
 
 
 /* static */
-const LeftEyeView& LeftEyeView::getInstance(float ipd)
+const LeftEyeView& LeftEyeView::getInstance(FLOATTYPE ipd)
 {
 	static LeftEyeView instance(ipd);
 	instance.setIpd(ipd);
@@ -68,7 +68,7 @@ const LeftEyeView& LeftEyeView::getInstance(float ipd)
 
 
 /* static */
-const RightEyeView& RightEyeView::getInstance(float ipd)
+const RightEyeView& RightEyeView::getInstance(FLOATTYPE ipd)
 {
 	static RightEyeView instance(ipd);
 	instance.setIpd(ipd);
diff --git a/src/gl/stereo3d/gl_stereo_leftright.h b/src/gl/stereo3d/gl_stereo_leftright.h
index 78f66e7fe..228b6459f 100644
--- a/src/gl/stereo3d/gl_stereo_leftright.h
+++ b/src/gl/stereo3d/gl_stereo_leftright.h
@@ -9,31 +9,31 @@ namespace s3d {
 class ShiftedEyePose : public EyePose
 {
 public:
-	ShiftedEyePose(float shift) : shift(shift) {};
-	float getShift() const { return shift; }
-	void setShift(float shift) { this->shift = shift; }
-	virtual void GetProjection(float fov, float aspectRatio, float fovRatio, GLdouble outMatrix[4][4]) const;
-	virtual void GetViewShift(float yaw, float outViewShift[3]) const;
+	ShiftedEyePose(FLOATTYPE shift) : shift(shift) {};
+	FLOATTYPE getShift() const { return shift; }
+	void setShift(FLOATTYPE shift) { this->shift = shift; }
+	virtual void GetProjection(FLOATTYPE fov, FLOATTYPE aspectRatio, FLOATTYPE fovRatio, FLOATTYPE outMatrix[4][4]) const;
+	virtual void GetViewShift(FLOATTYPE yaw, FLOATTYPE outViewShift[3]) const;
 protected:
-	float shift;
+	FLOATTYPE shift;
 };
 
 
 class LeftEyePose : public ShiftedEyePose
 {
 public:
-	LeftEyePose(float ipd) : ShiftedEyePose(-0.5*ipd) {}
-	float getIpd() const { return -2.0*getShift(); }
-	void setIpd(float ipd) { setShift(-0.5*ipd); }
+	LeftEyePose(FLOATTYPE ipd) : ShiftedEyePose( FLOATTYPE(-0.5) * ipd) {}
+	FLOATTYPE getIpd() const { return FLOATTYPE(-2.0)*getShift(); }
+	void setIpd(FLOATTYPE ipd) { setShift(FLOATTYPE(-0.5)*ipd); }
 };
 
 
 class RightEyePose : public ShiftedEyePose
 {
 public:
-	RightEyePose(float ipd) : ShiftedEyePose(+0.5*ipd) {}
-	float getIpd() const { return +2.0*shift; }
-	void setIpd(float ipd) { setShift(+0.5*ipd); }
+	RightEyePose(FLOATTYPE ipd) : ShiftedEyePose(FLOATTYPE(+0.5)*ipd) {}
+	FLOATTYPE getIpd() const { return FLOATTYPE(+2.0)*shift; }
+	void setIpd(FLOATTYPE ipd) { setShift(FLOATTYPE(+0.5)*ipd); }
 };
 
 
@@ -43,11 +43,11 @@ public:
 class LeftEyeView : public Stereo3DMode
 {
 public:
-	static const LeftEyeView& getInstance(float ipd);
+	static const LeftEyeView& getInstance(FLOATTYPE ipd);
 
-	LeftEyeView(float ipd) : eye(ipd) { eye_ptrs.push_back(&eye); }
-	float getIpd() const { return eye.getIpd(); }
-	void setIpd(float ipd) { eye.setIpd(ipd); }
+	LeftEyeView(FLOATTYPE ipd) : eye(ipd) { eye_ptrs.push_back(&eye); }
+	FLOATTYPE getIpd() const { return eye.getIpd(); }
+	void setIpd(FLOATTYPE ipd) { eye.setIpd(ipd); }
 protected:
 	LeftEyePose eye;
 };
@@ -56,11 +56,11 @@ protected:
 class RightEyeView : public Stereo3DMode
 {
 public:
-	static const RightEyeView& getInstance(float ipd);
+	static const RightEyeView& getInstance(FLOATTYPE ipd);
 
-	RightEyeView(float ipd) : eye(ipd) { eye_ptrs.push_back(&eye); }
-	float getIpd() const { return eye.getIpd(); }
-	void setIpd(float ipd) { eye.setIpd(ipd); }
+	RightEyeView(FLOATTYPE ipd) : eye(ipd) { eye_ptrs.push_back(&eye); }
+	FLOATTYPE getIpd() const { return eye.getIpd(); }
+	void setIpd(FLOATTYPE ipd) { eye.setIpd(ipd); }
 protected:
 	RightEyePose eye;
 };
diff --git a/src/gl/stereo3d/scoped_color_mask.h b/src/gl/stereo3d/scoped_color_mask.h
index cc3a1df1d..f746ba9e4 100644
--- a/src/gl/stereo3d/scoped_color_mask.h
+++ b/src/gl/stereo3d/scoped_color_mask.h
@@ -1,7 +1,7 @@
 #ifndef GL_STEREO3D_SCOPED_COLOR_MASK_H_
 #define GL_STEREO3D_SCOPED_COLOR_MASK_H_
 
-#include "gl/glew.h"
+#include "gl/system/gl_system.h"
 
 /**
 * Temporarily change color mask
@@ -10,28 +10,15 @@ class ScopedColorMask
 {
 public:
 	ScopedColorMask(GLboolean r, GLboolean g, GLboolean b, GLboolean a) 
-		: isPushed(false)
 	{
-		setColorMask(r, g, b, a);
-	}
-	~ScopedColorMask() {
-		revert();
-	}
-	void setColorMask(GLboolean r, GLboolean g, GLboolean b, GLboolean a) {
-		if (!isPushed) {
-			glPushAttrib(GL_COLOR_BUFFER_BIT);
-			isPushed = true;
-		}
+		glGetBooleanv(GL_COLOR_WRITEMASK, saved);
 		glColorMask(r, g, b, a);
 	}
-	void revert() {
-		if (isPushed) {
-			glPopAttrib();
-			isPushed = false;
-		}
+	~ScopedColorMask() {
+		glColorMask(saved[0], saved[1], saved[2], saved[3]);
 	}
 private:
-	bool isPushed;
+	GLboolean saved[4];
 };
 
 
diff --git a/wadsrc/static/menudef.z b/wadsrc/static/menudef.z
index 75ea1bf5f..3874b0328 100644
--- a/wadsrc/static/menudef.z
+++ b/wadsrc/static/menudef.z
@@ -124,6 +124,15 @@ OptionValue "FuzzStyle"
 	//5, "Jagged fuzz" I can't see any difference between this and 4 so it's disabled for now.
 }
 
+OptionValue VRMode
+{
+	0, "Normal"
+	1, "Green/Magenta"
+	2, "Red/Cyan"
+	5, "Left Eye"
+	6, "Right Eye"
+}
+
 OptionMenu "GLTextureGLOptions"
 {
 	Title "TEXTURE OPTIONS"
@@ -173,5 +182,6 @@ OptionMenu "GLPrefOptions"
 	Option "Particle style",			gl_particles_style,				"Particles"
 	Slider "Ambient light level",		gl_light_ambient,				1.0, 255.0, 5.0
 	Option "Rendering quality",			gl_render_precise,				"Precision"
+	Option "Stereo 3D VR",				vr_mode, 						"VRMode"
 }