Add a bit conditional compiling

Source/Engine/Core/Config.h

@@ -41,6 +41,9 @@
 // Enable/disable assertion for Engine low layers
 #define ENABLE_ASSERTION_LOW_LAYERS ENABLE_ASSERTION && (BUILD_DEBUG || FLAX_TESTS)
 
+// Enable reverse z
+#define FLAX_REVERSE_Z 1
+
 // Scripting API defines (see C++ scripting documentation for more info)
 #define API_ENUM(...)
 #define API_CLASS(...)

Source/Engine/Graphics/RenderView.cpp

@@ -64,7 +64,11 @@ void RenderView::Prepare(RenderContext& renderContext)
 void RenderView::PrepareCache(const RenderContext& renderContext, float width, float height, const Float2& temporalAAJitter, const RenderView* mainView)
 {
     // The same format used by the Flax common shaders and postFx materials
-    ViewInfo = Float4(1.0f / Projection.M11, 1.0f / Projection.M22, Near / (Far - Near), (Far * Near) / (Far - Near) / Far);
+#if FLAX_REVERSE_Z
+    ViewInfo = Float4(1.0f / Projection.M11, 1.0f / Projection.M22, -Near / (Far - Near), (Far * Near) / (Far - Near) / Far);
+#else
+    ViewInfo = Float4(1.0f / Projection.M11, 1.0f / Projection.M22, Far / (Far - Near), -(Far * Near) / (Far - Near) / Far);
+#endif
     ScreenSize = Float4(width, height, 1.0f / width, 1.0f / height);
 
     TemporalAAJitter.Z = TemporalAAJitter.X;

Source/Engine/Particles/Graph/GPU/ParticleEmitterGraph.GPU.ParticleModules.cpp

@@ -840,7 +840,7 @@ void ParticleEmitterGPUGenerator::ProcessModule(Node* node)
                 "			uint2 pixel = uv * ScreenSize.xy;\n"
 
                 "			float depth = {11}.Load(uint3(pixel, 0)).r;\n"
-                "			float linearDepth = ViewInfo.w / (depth + ViewInfo.z) * ViewFar;\n"
+                "			float linearDepth = ViewInfo.w / (depth - ViewInfo.z) * ViewFar;\n"
 
                 "			if (viewPos.z > linearDepth - {5} && viewPos.z < linearDepth + {5} + {10})\n"
                 "			{{\n"

Source/Engine/Particles/Graph/GPU/ParticleEmitterGraph.GPU.Textures.cpp

@@ -144,7 +144,7 @@ void ParticleEmitterGPUGenerator::sampleSceneDepth(Node* caller, Value& value, B
 
 void ParticleEmitterGPUGenerator::linearizeSceneDepth(Node* caller, const Value& depth, Value& value)
 {
-    value = writeLocal(VariantType::Float, String::Format(TEXT("ViewInfo.w / ({0}.x + ViewInfo.z)"), depth.Value), caller);
+    value = writeLocal(VariantType::Float, String::Format(TEXT("ViewInfo.w / ({0}.x - ViewInfo.z)"), depth.Value), caller);
 }
 
 void ParticleEmitterGPUGenerator::ProcessGroupTextures(Box* box, Node* node, Value& value)

Source/Engine/Renderer/DepthOfFieldPass.cpp

@@ -277,8 +277,13 @@ void DepthOfFieldPass::Render(RenderContext& renderContext, GPUTexture*& frame,
         cbData.BokehTargetSize.Y = static_cast<float>(bokehTargetHeight);
 
         // TODO: use projection matrix instead of this far and near stuff?
-        cbData.ProjectionAB.X = nearPlane / (farPlane - nearPlane);
+#if FLAX_REVERSE_Z
+        cbData.ProjectionAB.X = -nearPlane / (farPlane - nearPlane);
         cbData.ProjectionAB.Y = (farPlane * nearPlane) / (farPlane - nearPlane);
+#else
+        cbData.ProjectionAB.X = farPlane / (farPlane - nearPlane);
+        cbData.ProjectionAB.Y = -(farPlane * nearPlane) / (farPlane - nearPlane);
+#endif
 
         auto cb = shader->GetCB(0);
         context->UpdateCB(cb, &cbData);

Source/Engine/Tools/MaterialGenerator/MaterialGenerator.Textures.cpp

@@ -160,7 +160,7 @@ void MaterialGenerator::sampleSceneDepth(Node* caller, Value& value, Box* box)
 
 void MaterialGenerator::linearizeSceneDepth(Node* caller, const Value& depth, Value& value)
 {
-    value = writeLocal(VariantType::Float, String::Format(TEXT("ViewInfo.w / ({0}.x + ViewInfo.z)"), depth.Value), caller);
+    value = writeLocal(VariantType::Float, String::Format(TEXT("ViewInfo.w / ({0}.x - ViewInfo.z)"), depth.Value), caller);
 }
 
 void MaterialGenerator::ProcessGroupTextures(Box* box, Node* node, Value& value)

Source/Shaders/DepthOfField.shader

@@ -96,7 +96,7 @@ Texture2D Input1 : register(t1);
 // Converts z-buffer depth to linear view-space depth
 float LinearDepth(in float zBufferDepth)
 {
-	return ProjectionAB.y / (zBufferDepth + ProjectionAB.x);
+	return ProjectionAB.y / (zBufferDepth - ProjectionAB.x);
 }
 
 // Depth of Field depth blur generation (outputs linear depth + blur factor to R16G16 target)

Source/Shaders/GBuffer.hlsl

@@ -27,13 +27,13 @@ Texture2D GBuffer3 : register(t4);
 // Linearize raw device depth
 float LinearizeZ(GBufferData gBuffer, float depth)
 {
-    return gBuffer.ViewInfo.w / (depth + gBuffer.ViewInfo.z);
+    return gBuffer.ViewInfo.w / (depth - gBuffer.ViewInfo.z);
 }
 
 // Convert linear depth to device depth
 float LinearZ2DeviceDepth(GBufferData gBuffer, float linearDepth)
 {
-    return ((gBuffer.ViewInfo.w / linearDepth) - gBuffer.ViewInfo.z);
+    return ((gBuffer.ViewInfo.w / linearDepth) + gBuffer.ViewInfo.z);
 }
 
 // Get view space position at given pixel coordinate with given device depth