From a9c2e316b6f856be8473ad9d0f9a8382ae9dd94d Mon Sep 17 00:00:00 2001
From: Robert Beckebans <robert.beckebans@gmail.com>
Date: Thu, 31 Oct 2019 15:22:28 +0100
Subject: [PATCH] Added Experiment to compile GLSL to SPIR-V using shaderc

---
 neo/CMakeLists.txt                          | 53 ++++++++++++------
 neo/cmake-vs2017-64bit-windows10-vulkan.bat |  2 +-
 neo/renderer/Vulkan/RenderProgs_VK.cpp      | 59 ++++++++++++++++++++-
 3 files changed, 94 insertions(+), 20 deletions(-)

diff --git a/neo/CMakeLists.txt b/neo/CMakeLists.txt
index 5ae298c2..928a24ee 100644
--- a/neo/CMakeLists.txt
+++ b/neo/CMakeLists.txt
@@ -27,6 +27,9 @@ option(BINKDEC
 option(USE_VULKAN
 		"Use Vulkan instead of OpenGL" OFF)
 
+option(SPIRV_SHADERC
+		"Compile SPIR-V shader byte code using shaderc instead of using Glslang directly" OFF)
+
 option(ONATIVE
 		"Optimize for the host CPU" OFF)
 		
@@ -293,22 +296,34 @@ if(USE_VULKAN)
 	endif()
 	
 	add_definitions(-DUSE_VULKAN)
-	include_directories($ENV{VK_SDK_PATH}/Include)
+	include_directories($ENV{VULKAN_SDK}/Include)
 	
-	# override Glslang build options
-	SET_OPTION(ENABLE_SPVREMAPPER OFF)
-	SET_OPTION(ENABLE_GLSLANG_BINARIES OFF)
-	SET_OPTION(ENABLE_HLSL OFF)
-	#SET_OPTION(ENABLE_OPT OFF)
+	if(SPIRV_SHADERC)
+		add_definitions(-DSPIRV_SHADERC)
+
+		if(CMAKE_CL_64)
+			link_directories($ENV{VULKAN_SDK}/Lib)
+		else()
+			link_directories($ENV{VULKAN_SDK}/Lib32)
+		endif()
+
+	else()
+		# override Glslang build options
+		SET_OPTION(ENABLE_SPVREMAPPER OFF)
+		SET_OPTION(ENABLE_GLSLANG_BINARIES OFF)
+		SET_OPTION(ENABLE_HLSL OFF)
+		SET_OPTION(ENABLE_OPT ON)
+		SET_OPTION(SPIRV_SKIP_EXECUTABLES ON)
 	
-	#option(ENABLE_AMD_EXTENSIONS "Enables support of AMD-specific extensions" ON)
-	#option(ENABLE_NV_EXTENSIONS "Enables support of Nvidia-specific extensions" ON)
-	#option(ENABLE_OPT "Enables spirv-opt capability if present" ON)
+		#option(ENABLE_AMD_EXTENSIONS "Enables support of AMD-specific extensions" ON)
+		#option(ENABLE_NV_EXTENSIONS "Enables support of Nvidia-specific extensions" ON)
+		#option(ENABLE_OPT "Enables spirv-opt capability if present" ON)
 	
-	set(GLSLANG_DIR ${CMAKE_CURRENT_SOURCE_DIR}/libs/glslang)
-	add_subdirectory(${GLSLANG_DIR})
+		set(GLSLANG_DIR ${CMAKE_CURRENT_SOURCE_DIR}/libs/glslang)
+		add_subdirectory(${GLSLANG_DIR})
 	
-	include_directories(${GLSLANG_DIR}/glslang)
+		include_directories(${GLSLANG_DIR}/glslang)
+	endif()
 
 else()
 
@@ -1309,12 +1324,16 @@ if(MSVC)
 		
 		set(Vulkan_LIBRARIES
 			${Vulkan_LIBRARY}
-			glslang
-			SPIRV
 			)
-			
-		if(ENABLE_GLSLANG_BINARIES)
-			list(APPEND Vulkan_LIBRARIES glslang-default-resource-limits)
+
+		if(SPIRV_SHADERC)
+			list(APPEND Vulkan_LIBRARIES shaderc_combined)
+		else()
+			list(APPEND Vulkan_LIBRARIES glslang SPIRV)
+
+			if(ENABLE_GLSLANG_BINARIES)
+				list(APPEND Vulkan_LIBRARIES glslang-default-resource-limits)
+			endif()
 		endif()
 		
 	else()
diff --git a/neo/cmake-vs2017-64bit-windows10-vulkan.bat b/neo/cmake-vs2017-64bit-windows10-vulkan.bat
index d67e1a7d..b5d41809 100644
--- a/neo/cmake-vs2017-64bit-windows10-vulkan.bat
+++ b/neo/cmake-vs2017-64bit-windows10-vulkan.bat
@@ -2,5 +2,5 @@ cd ..
 del /s /q build
 mkdir build
 cd build
-cmake -G "Visual Studio 15 Win64" -DWINDOWS10=ON -DUSE_VULKAN=ON -DUSE_FFMPEG=ON ../neo
+cmake -G "Visual Studio 15 Win64" -DWINDOWS10=ON -DUSE_VULKAN=ON -DSPIRV_SHADERC=OFF -DFFMPEG=OFF ../neo
 pause
\ No newline at end of file
diff --git a/neo/renderer/Vulkan/RenderProgs_VK.cpp b/neo/renderer/Vulkan/RenderProgs_VK.cpp
index a528ac3d..f2c96f9c 100644
--- a/neo/renderer/Vulkan/RenderProgs_VK.cpp
+++ b/neo/renderer/Vulkan/RenderProgs_VK.cpp
@@ -337,9 +337,64 @@ void idRenderProgManager::LoadShader( int index, rpStage_t stage )
 CompileGLSLtoSPIRV
 ================================================================================================
 */
-#define USE_GLSLANG 1
 
-#if defined(USE_GLSLANG)
+
+#if defined(SPIRV_SHADERC)
+
+#include <shaderc/shaderc.hpp>
+
+static int CompileGLSLtoSPIRV( const char* filename, const idStr& dataGLSL, const rpStage_t stage, uint32** spirvBuffer )
+{
+	shaderc::Compiler compiler;
+	shaderc::CompileOptions options;
+	
+	// Like -DMY_DEFINE=1
+	//options.AddMacroDefinition("MY_DEFINE", "1");
+	
+	//if (optimize)
+	{
+		options.SetOptimizationLevel( shaderc_optimization_level_size );
+	}
+	
+	shaderc_shader_kind shaderKind;
+	if( stage == SHADER_STAGE_VERTEX )
+	{
+		shaderKind = shaderc_glsl_vertex_shader;
+	}
+	else if( stage == SHADER_STAGE_COMPUTE )
+	{
+		shaderKind = shaderc_glsl_compute_shader;
+	}
+	else
+	{
+		shaderKind = shaderc_glsl_fragment_shader;
+	}
+	
+	std::string source = dataGLSL.c_str();
+	
+	shaderc::SpvCompilationResult module = compiler.CompileGlslToSpv( source, shaderKind, filename, options );
+	
+	if( module.GetCompilationStatus() != shaderc_compilation_status_success )
+	{
+		idLib::Printf( "Comping GLSL to SPIR-V using shaderc failed for: %s\n", filename );
+		idLib::Printf( "%s\n", module.GetErrorMessage().c_str() );
+		return 0;
+	}
+	
+	std::vector<uint32_t> spirV = { module.cbegin(), module.cend() };
+	
+	// copy to spirvBuffer
+	int32 spirvLen = spirV.size() * sizeof( uint32_t );
+	
+	void* buffer = Mem_Alloc( spirvLen, TAG_RENDERPROG );
+	memcpy( buffer, spirV.data(), spirvLen );
+	
+	*spirvBuffer = ( uint32_t* ) buffer;
+	return spirvLen;
+	
+	
+}
+#else
 
 #include <glslang/public/ShaderLang.h>
 #include <glslang/Include/ResourceLimits.h>