- use layout binding qualifiers on uniform buffers when GLSL version >= 4.2

This has no performance benefits but allows checking shader generation correctness without having to implement Vulkan first.

src/gl/shaders/gl_shaderprogram.cpp

@@ -145,9 +145,12 @@ void FShaderProgram::Link(const char *name)
 
 void FShaderProgram::SetUniformBufferLocation(int index, const char *name)
 {
-	GLuint uniformBlockIndex = glGetUniformBlockIndex(mProgram, name);
-	if (uniformBlockIndex != GL_INVALID_INDEX)
-		glUniformBlockBinding(mProgram, uniformBlockIndex, index);
+	if (screen->glslversion < 4.20)
+	{
+		GLuint uniformBlockIndex = glGetUniformBlockIndex(mProgram, name);
+		if (uniformBlockIndex != GL_INVALID_INDEX)
+			glUniformBlockBinding(mProgram, uniformBlockIndex, index);
+	}
 }
 
 //==========================================================================
@@ -201,6 +204,8 @@ FString FShaderProgram::PatchShader(ShaderType type, const FString &code, const
 {
 	FString patchedCode;
 
+	// If we have 4.2, always use it because it adds important new syntax.
+	if (maxGlslVersion < 420 && gl.glslversion >= 4.2f) maxGlslVersion = 420;
 	int shaderVersion = MIN((int)round(gl.glslversion * 10) * 10, maxGlslVersion);
 	if (gl.es)
 		patchedCode.AppendFormat("#version %d es\n", shaderVersion);
@@ -224,11 +229,3 @@ FString FShaderProgram::PatchShader(ShaderType type, const FString &code, const
 
 	return patchedCode;
 }
-
-//==========================================================================
-//
-// patch the shader source to work with 
-// GLSL 1.2 keywords and identifiers
-//
-//==========================================================================
-

src/gl/system/gl_framebuffer.cpp

@@ -82,8 +82,11 @@ OpenGLFrameBuffer::OpenGLFrameBuffer(void *hMonitor, int width, int height, int
 	mDebug = std::make_shared<FGLDebug>();
 	mDebug->Update();
 	SetGamma();
+
+	// Move some state to the framebuffer object for easier access.
 	hwcaps = gl.flags;
 	if (gl.legacyMode) hwcaps |= RFL_NO_SHADERS;
+	glslversion = gl.glslversion;
 }
 
 OpenGLFrameBuffer::~OpenGLFrameBuffer()

src/gl/system/gl_framebuffer.h

@@ -45,7 +45,6 @@ public:
 	void SetViewportRects(IntRect *bounds) override;
 	void BlurScene(float amount) override;
     IUniformBuffer *CreateUniformBuffer(size_t size, bool staticuse = false) override;
-    virtual FString GetUniformLayoutString(int bindingpoint) { return "std140"; }
 
 
 	// Retrieves a buffer containing image data for a screenshot.

src/gl_load/gl_interface.cpp

@@ -225,6 +225,7 @@ void gl_LoadExtensions()
 					gl.flags |= RFL_NO_CLIP_PLANES;	// gl_ClipDistance is horribly broken on ATI GL3 drivers for Windows.
 				}
 #endif
+				gl.glslversion = 3.31f;	// Force GLSL down to 3.3.
 			}
 			else if (gl_version < 4.5f)
 			{

src/hwrenderer/data/shaderuniforms.h

@@ -57,7 +57,16 @@ public:
 		mFields = fields;
 
 		FString decl;
-		decl.Format("layout(%s) uniform %s\n{\n", screen->GetUniformLayoutString(bindingpoint).GetChars(), name);
+		FString layout;
+		if (screen->glslversion < 4.20)
+		{
+			layout = "std140";
+		}
+		else
+		{
+			layout.Format("std140, binding = %d", bindingpoint);
+		}
+		decl.Format("layout(%s) uniform %s\n{\n", layout.GetChars(), name);
 		for (const auto &field : fields)
 		{
 			decl.AppendFormat("\t%s %s;\n", GetTypeStr(field.Type), field.Name);
@@ -117,3 +126,46 @@ private:
 	std::vector<UniformFieldDesc> mFields;
 };
 
+
+enum class SamplerType : int
+{
+	Sampler1D,
+	Sampler2D,
+	Sampler3D,
+	SamplerCube,
+	iSampler1D,
+	iSampler2D,
+	iSampler3D,
+	iSamplerCube,
+	uSampler1D,
+	uSampler2D,
+	uSampler3D,
+	uSamplerCube,
+};
+
+struct SamplerUniform
+{
+	const char *GetTypeStr() const
+	{
+		switch (mType)
+		{
+		default:
+		case SamplerType::Sampler1D: return "sampler1D";
+		case SamplerType::Sampler2D: return "sampler2D";
+		case SamplerType::Sampler3D: return "sampler3D";
+		case SamplerType::SamplerCube: return "samplerCube";
+		case SamplerType::iSampler1D: return "isampler1D";
+		case SamplerType::iSampler2D: return "isampler2D";
+		case SamplerType::iSampler3D: return "isampler3D";
+		case SamplerType::iSamplerCube: return "isamplerCube";
+		case SamplerType::uSampler1D: return "usampler1D";
+		case SamplerType::uSampler2D: return "usampler2D";
+		case SamplerType::uSampler3D: return "usampler3D";
+		case SamplerType::uSamplerCube: return "usamplerCube";
+		}
+	}
+			
+	int mBinding;
+	SamplerType mType;
+	const char *mName;
+};

src/v_video.h

@@ -349,6 +349,7 @@ protected:
 
 public:
 	int hwcaps = 0;
+	float glslversion = 0;			// This is here so that the differences between old OpenGL and new OpenGL/Vulkan can be handled by platform independent code.
 	int instack[2] = { 0,0 };	// this is globally maintained state for portal recursion avoidance.
 	bool enable_quadbuffered = false;
 
@@ -416,7 +417,6 @@ public:
     
     // Interface to hardware rendering resources
     virtual IUniformBuffer *CreateUniformBuffer(size_t size, bool staticuse = false) { return nullptr; }
-    virtual FString GetUniformLayoutString(int bindingpoint) { return ""; }
 
 	// Begin 2D drawing operations.
 	// Returns true if hardware-accelerated 2D has been entered, false if not.