From 05a8c841da9067bed66f09a7ad1bfc8cf27e8b9f Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 28 Oct 2025 23:19:51 +0100
Subject: [PATCH] Fix color grading lut to be refreshed when shader gets
 reloaded

---
 Content/Shaders/ColorGrading.flax           |  4 ++--
 Source/Engine/Renderer/ColorGradingPass.cpp | 20 ++++++++++++++++++++
 Source/Engine/Renderer/ColorGradingPass.h   |  7 ++-----
 Source/Shaders/ColorGrading.shader          |  7 +++----
 Source/Shaders/GammaCorrectionCommon.hlsl   |  7 ++-----
 5 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/Content/Shaders/ColorGrading.flax b/Content/Shaders/ColorGrading.flax
index 15f723620..716e18593 100644
--- a/Content/Shaders/ColorGrading.flax
+++ b/Content/Shaders/ColorGrading.flax
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:ad1d9597dd930f0b63358dbe8326d131661f9cc2251181eeec0cb44ffc530d7a
-size 12311
+oid sha256:bce57f0ccf6d808985f4d79cc4e15d85cae999bee598d8e93ff5b1b126bc42b8
+size 12310
diff --git a/Source/Engine/Renderer/ColorGradingPass.cpp b/Source/Engine/Renderer/ColorGradingPass.cpp
index bbb45ef4c..d6e164622 100644
--- a/Source/Engine/Renderer/ColorGradingPass.cpp
+++ b/Source/Engine/Renderer/ColorGradingPass.cpp
@@ -47,6 +47,9 @@ public:
     Data CachedData;
     ToneMappingMode Mode = ToneMappingMode::None;
     Texture* LutTexture = nullptr;
+#if COMPILE_WITH_DEV_ENV
+    uint64 FrameRendered = 0;
+#endif
 
     ~ColorGradingCustomBuffer()
     {
@@ -54,6 +57,17 @@ public:
     }
 };
 
+#if COMPILE_WITH_DEV_ENV
+
+void ColorGradingPass::OnShaderReloading(Asset* obj)
+{
+    _psLut.Release();
+    invalidateResources();
+    _reloadedFrame = Engine::FrameCount;
+}
+
+#endif
+
 String ColorGradingPass::ToString() const
 {
     return TEXT("ColorGradingPass");
@@ -194,6 +208,9 @@ GPUTexture* ColorGradingPass::RenderLUT(RenderContext& renderContext)
     // Check if LUT parameter hasn't been changed since the last time
     if (Platform::MemoryCompare(&colorGradingBuffer.CachedData , &data, sizeof(Data)) == 0 &&
         colorGradingBuffer.Mode == toneMapping.Mode &&
+#if COMPILE_WITH_DEV_ENV
+        colorGradingBuffer.FrameRendered > _reloadedFrame &&
+#endif
         Engine::FrameCount > 30 && // Skip caching when engine is starting TODO: find why this hack is needed
         colorGradingBuffer.LutTexture == lutTexture)
     {
@@ -203,6 +220,9 @@ GPUTexture* ColorGradingPass::RenderLUT(RenderContext& renderContext)
     colorGradingBuffer.CachedData = data;
     colorGradingBuffer.Mode = toneMapping.Mode;
     colorGradingBuffer.LutTexture = lutTexture;
+#if COMPILE_WITH_DEV_ENV
+    colorGradingBuffer.FrameRendered = Engine::FrameCount;
+#endif
 
     // Render LUT
     PROFILE_GPU("Color Grading LUT");
diff --git a/Source/Engine/Renderer/ColorGradingPass.h b/Source/Engine/Renderer/ColorGradingPass.h
index 612940e76..dd17e7786 100644
--- a/Source/Engine/Renderer/ColorGradingPass.h
+++ b/Source/Engine/Renderer/ColorGradingPass.h
@@ -25,11 +25,8 @@ public:
 
 private:
 #if COMPILE_WITH_DEV_ENV
-    void OnShaderReloading(Asset* obj)
-    {
-        _psLut.Release();
-        invalidateResources();
-    }
+    uint64 _reloadedFrame = 0;
+    void OnShaderReloading(Asset* obj);
 #endif
 
 public:
diff --git a/Source/Shaders/ColorGrading.shader b/Source/Shaders/ColorGrading.shader
index 9d1d71697..fe2ca4c91 100644
--- a/Source/Shaders/ColorGrading.shader
+++ b/Source/Shaders/ColorGrading.shader
@@ -164,16 +164,14 @@ float3 TonemapACES(float3 linearColor)
 	// The code was originally written by Stephen Hill (@self_shadow).
 
 	// sRGB => XYZ => D65_2_D60 => AP1 => RRT_SAT
-	static const float3x3 ACESInputMat =
-	{
+	static const float3x3 ACESInputMat = {
 		{0.59719, 0.35458, 0.04823},
 		{0.07600, 0.90834, 0.01566},
 		{0.02840, 0.13383, 0.83777}
 	};
 
 	// ODT_SAT => XYZ => D60_2_D65 => sRGB
-	static const float3x3 ACESOutputMat =
-	{
+	static const float3x3 ACESOutputMat = {
 		{ 1.60475, -0.53108, -0.07367},
 		{-0.10208,  1.10813, -0.00605},
 		{-0.00327, -0.07276,  1.07602}
@@ -188,6 +186,7 @@ float3 TonemapACES(float3 linearColor)
 	color = a / b;
 
 	color = mul(ACESOutputMat, color);
+
 	return saturate(color);
 }
 
diff --git a/Source/Shaders/GammaCorrectionCommon.hlsl b/Source/Shaders/GammaCorrectionCommon.hlsl
index b687f9166..e410400ad 100644
--- a/Source/Shaders/GammaCorrectionCommon.hlsl
+++ b/Source/Shaders/GammaCorrectionCommon.hlsl
@@ -37,7 +37,7 @@ float4 FastTonemapInvert(float4 c)
     return float4(FastTonemapInvert(c.rgb), c.a);
 }
 
-float LinearToSrgbChannel(float linearColor)
+float LinearToSrgb(float linearColor)
 {
     if (linearColor < 0.00313067)
         return linearColor * 12.92;
@@ -46,10 +46,7 @@ float LinearToSrgbChannel(float linearColor)
 
 float3 LinearToSrgb(float3 linearColor)
 {
-    return float3(
-        LinearToSrgbChannel(linearColor.r),
-        LinearToSrgbChannel(linearColor.g),
-        LinearToSrgbChannel(linearColor.b));
+    return float3(LinearToSrgb(linearColor.r), LinearToSrgb(linearColor.g), LinearToSrgb(linearColor.b));
 }
 
 float3 sRGBToLinear(float3 color)