Add support for depthBiasClamp

src/Device/Context.hpp

@@ -103,6 +103,7 @@ public:
 
 	float depthBias;
 	float slopeDepthBias;
+	float depthBiasClamp;
 
 	VkFormat renderTargetInternalFormat(int index) const;
 	int colorWriteActive(int index) const;

src/Device/Renderer.cpp

@@ -338,6 +338,7 @@ void Renderer::draw(const sw::Context *context, VkIndexType indexType, unsigned
 		data->halfPixelY = float4(0.5f / H);
 		data->viewportHeight = abs(viewport.height);
 		data->slopeDepthBias = context->slopeDepthBias;
+		data->depthBiasClamp = context->depthBiasClamp;
 		data->depthRange = Z;
 		data->depthNear = N;
 	}

src/Device/Renderer.hpp

@@ -90,6 +90,7 @@ struct DrawData
 	float slopeDepthBias;
 	float depthRange;
 	float depthNear;
+	float depthBiasClamp;
 
 	unsigned int *colorBuffer[RENDERTARGETS];
 	int colorPitchB[RENDERTARGETS];

src/Device/SetupProcessor.cpp

@@ -65,6 +65,7 @@ SetupProcessor::State SetupProcessor::update(const sw::Context *context) const
 	state.isDrawLine = context->isDrawLine(true);
 	state.isDrawTriangle = context->isDrawTriangle(true);
 	state.applySlopeDepthBias = context->isDrawTriangle(false) && (context->slopeDepthBias != 0.0f);
+	state.applyDepthBiasClamp = context->isDrawTriangle(false) && (context->depthBiasClamp != 0.0f);
 	state.interpolateZ = context->depthBufferActive() || vPosZW;
 	state.interpolateW = context->pixelShader != nullptr;
 	state.frontFace = context->frontFace;

src/Device/SetupProcessor.hpp

@@ -49,6 +49,7 @@ public:
 		bool isDrawLine : 1;
 		bool isDrawTriangle : 1;
 		bool applySlopeDepthBias : 1;
+		bool applyDepthBiasClamp : 1;
 		bool interpolateZ : 1;
 		bool interpolateW : 1;
 		VkFrontFace frontFace : BITS(VK_FRONT_FACE_MAX_ENUM);

src/Pipeline/SetupRoutine.cpp

@@ -443,6 +443,13 @@ void SetupRoutine::generate()
 
 			C = Float4(c * *Pointer<Float>(data + OFFSET(DrawData, depthRange)) + *Pointer<Float>(data + OFFSET(DrawData, depthNear)));
 
+			if(state.applyDepthBiasClamp)
+			{
+				Float clamp = *Pointer<Float>(data + OFFSET(DrawData, depthBiasClamp));
+				Float4 clamp4 = Float4(clamp);
+				C = IfThenElse(clamp > 0.0f, Min(clamp4, C), Max(clamp4, C));
+			}
+
 			*Pointer<Float4>(primitive + OFFSET(Primitive, z.C), 16) = C;
 		}
 

src/Vulkan/VkCommandBuffer.cpp

@@ -547,11 +547,9 @@ public:
 
 		if(pipeline->hasDynamicState(VK_DYNAMIC_STATE_DEPTH_BIAS))
 		{
-			// If the depth bias clamping feature is not enabled, depthBiasClamp must be 0.0
-			ASSERT(executionState.dynamicState.depthBiasClamp == 0.0f);
-
 			context.depthBias = executionState.dynamicState.depthBiasConstantFactor;
 			context.slopeDepthBias = executionState.dynamicState.depthBiasSlopeFactor;
+			context.depthBiasClamp = executionState.dynamicState.depthBiasClamp;
 		}
 
 		if(pipeline->hasDynamicState(VK_DYNAMIC_STATE_DEPTH_BOUNDS) && context.depthBoundsTestEnable)

src/Vulkan/VkPhysicalDevice.cpp

@@ -76,7 +76,7 @@ const VkPhysicalDeviceFeatures &PhysicalDevice::getFeatures() const
 		VK_TRUE,   // multiDrawIndirect
 		VK_TRUE,   // drawIndirectFirstInstance
 		VK_FALSE,  // depthClamp
-		VK_FALSE,  // depthBiasClamp
+		VK_TRUE,   // depthBiasClamp
 		VK_TRUE,   // fillModeNonSolid
 		VK_FALSE,  // depthBounds
 		VK_FALSE,  // wideLines

src/Vulkan/VkPipeline.cpp

@@ -260,6 +260,21 @@ GraphicsPipeline::GraphicsPipeline(const VkGraphicsPipelineCreateInfo *pCreateIn
 	context.polygonMode = rasterizationState->polygonMode;
 	context.depthBias = (rasterizationState->depthBiasEnable != VK_FALSE) ? rasterizationState->depthBiasConstantFactor : 0.0f;
 	context.slopeDepthBias = (rasterizationState->depthBiasEnable != VK_FALSE) ? rasterizationState->depthBiasSlopeFactor : 0.0f;
+	context.depthBiasClamp = (rasterizationState->depthBiasEnable != VK_FALSE) ? rasterizationState->depthBiasClamp : 0.0f;
+
+	// From the Vulkan spec for vkCmdSetDepthBias:
+	//    The bias value O for a polygon is:
+	//        O = dbclamp(...)
+	//    where dbclamp(x) =
+	//        * x                       depthBiasClamp = 0 or NaN
+	//        * min(x, depthBiasClamp)  depthBiasClamp > 0
+	//        * max(x, depthBiasClamp)  depthBiasClamp < 0
+	// So it should be safe to resolve NaNs to 0.0f.
+	if(std::isnan(context.depthBiasClamp))
+	{
+		context.depthBiasClamp = 0.0f;
+	}
+
 	context.lineWidth = rasterizationState->lineWidth;
 
 	const VkBaseInStructure *extensionCreateInfo = reinterpret_cast<const VkBaseInStructure *>(rasterizationState->pNext);