Added ColorConversion.h/cpp

4 files changed, 153 insertions, 14 deletions

diff --git a/Graphics/GraphicsAccessories/CMakeLists.txt b/Graphics/GraphicsAccessories/CMakeLists.txt
index 65f10313..6d194893 100644
--- a/Graphics/GraphicsAccessories/CMakeLists.txt
+++ b/Graphics/GraphicsAccessories/CMakeLists.txt
@@ -3,6 +3,7 @@ cmake_minimum_required (VERSION 3.6)
 project(GraphicsAccessories CXX)
 
 set(INTERFACE 
+    interface/ColorConversion.h
     interface/GraphicsAccessories.h
     interface/ResourceReleaseQueue.h
     interface/RingBuffer.h
@@ -11,7 +12,8 @@ set(INTERFACE
     interface/VariableSizeGPUAllocationsManager.h
 )
 
-set(SOURCE 
+set(SOURCE
+    src/ColorConversion.cpp
     src/SRBMemoryAllocator.cpp
     src/GraphicsAccessories.cpp
 )
diff --git a/Graphics/GraphicsAccessories/interface/ColorConversion.h b/Graphics/GraphicsAccessories/interface/ColorConversion.h
new file mode 100644
index 00000000..5403c930
--- /dev/null
+++ b/Graphics/GraphicsAccessories/interface/ColorConversion.h
@@ -0,0 +1,57 @@
+/*     Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PROPRIETARY RIGHTS.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#pragma once
+
+#include <cmath>
+#include "../../../Primitives/interface/BasicTypes.h"
+
+namespace Diligent
+{
+
+// https://en.wikipedia.org/wiki/SRGB
+inline float LinearToSRGB(float x)
+{
+    return x <= 0.0031308  ?  x * 12.92f  :  1.055f * std::pow(x, 1.f / 2.4f) - 0.055f;
+}
+
+inline float SRGBToLinear(float x)
+{
+    return x <= 0.04045f ? x / 12.92f : std::pow((x + 0.055f) / 1.055f, 2.4f);
+}
+
+float LinearToSRGB(Uint8 x);
+float SRGBToLinear(Uint8 x);
+
+inline float FastLinearToSRGB(float x)
+{
+    return x < 0.0031308f ? 12.92f * x : 1.13005f * sqrtf(std::abs(x - 0.00228f)) - 0.13448f * x + 0.005719f;
+}
+
+inline float FastSRGBToLinear(float x)
+{
+    // http://chilliant.blogspot.com/2012/08/srgb-approximations-for-hlsl.html
+    return x * (x * (x * 0.305306011f + 0.682171111f) + 0.012522878f);
+}
+
+}
diff --git a/Graphics/GraphicsAccessories/src/ColorConversion.cpp b/Graphics/GraphicsAccessories/src/ColorConversion.cpp
new file mode 100644
index 00000000..d917b8ab
--- /dev/null
+++ b/Graphics/GraphicsAccessories/src/ColorConversion.cpp
@@ -0,0 +1,88 @@
+/*     Copyright 2015-2019 Egor Yusov
+ *  
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PROPRIETARY RIGHTS.
+ *
+ *  In no event and under no legal theory, whether in tort (including negligence), 
+ *  contract, or otherwise, unless required by applicable law (such as deliberate 
+ *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
+ *  liable for any damages, including any direct, indirect, special, incidental, 
+ *  or consequential damages of any character arising as a result of this License or 
+ *  out of the use or inability to use the software (including but not limited to damages 
+ *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
+ *  all other commercial damages or losses), even if such Contributor has been advised 
+ *  of the possibility of such damages.
+ */
+
+#include <array>
+#include <algorithm>
+#include "ColorConversion.h"
+
+namespace Diligent
+{
+
+namespace
+{
+
+class LinearToSRGBMap
+{
+public:
+    LinearToSRGBMap() noexcept
+    {
+        for (Uint32 i=0; i < m_ToSRBG.size(); ++i)
+        {
+            m_ToSRBG[i] = LinearToSRGB(static_cast<float>(i) / 255.f);
+        }
+    }
+
+    float operator[](Uint8 x) const
+    {
+        return m_ToSRBG[x];
+    }
+
+private:
+    std::array<float, 256> m_ToSRBG;
+};
+
+class SRGBToLinearMap
+{
+public:
+    SRGBToLinearMap() noexcept
+    {
+        for (Uint32 i=0; i < m_ToLinear.size(); ++i)
+        {
+            m_ToLinear[i] = SRGBToLinear(static_cast<float>(i) / 255.f);
+        }
+    }
+
+    float operator[](Uint8 x) const
+    {
+        return m_ToLinear[x];
+    }
+
+private:
+    std::array<float, 256> m_ToLinear;
+};
+
+} // namespace
+
+float LinearToSRGB(Uint8 x)
+{
+    static const LinearToSRGBMap map;
+    return map[x];
+}
+
+float SRGBToLinear(Uint8 x)
+{
+    static const SRGBToLinearMap map;
+    return map[x];
+}
+
+} // namespace Diligent
diff --git a/Graphics/GraphicsTools/src/GraphicsUtilities.cpp b/Graphics/GraphicsTools/src/GraphicsUtilities.cpp
index 29837ec3..f1f85aa6 100644
--- a/Graphics/GraphicsTools/src/GraphicsUtilities.cpp
+++ b/Graphics/GraphicsTools/src/GraphicsUtilities.cpp
@@ -22,11 +22,13 @@
  */
 
 #include "pch.h"
+#include <algorithm>
+#include <cmath>
+
 #include "GraphicsUtilities.h"
 #include "DebugUtilities.h"
 #include "GraphicsAccessories.h"
-#include <algorithm>
-#include <cmath>
+#include "ColorConversion.h"
 
 #define PI_F 3.1415926f
 
@@ -64,16 +66,6 @@ void GenerateCheckerBoardPatternInternal(Uint32 Width, Uint32 Height, TEXTURE_FO
     }
 }
 
-static float LinearToSRGB(float x)
-{
-    // This is exactly the sRGB curve
-    //return x < 0.0031308 ? 12.92 * x : 1.055 * pow(std::abs(x), 1.0 / 2.4) - 0.055;
-
-    // This is cheaper but nearly equivalent
-    return x < 0.0031308f ? 12.92f * x : 1.13005f * sqrtf(std::abs(x - 0.00228f)) - 0.13448f * x + 0.005719f;
-}
-
-
 void GenerateCheckerBoardPattern(Uint32 Width, Uint32 Height, TEXTURE_FORMAT Fmt, Uint32 HorzCells, Uint32 VertCells, Uint8 *pData, Uint32 StrideInBytes)
 {
     const auto& FmtAttribs = GetTextureFormatAttribs(Fmt);
@@ -94,7 +86,7 @@ void GenerateCheckerBoardPattern(Uint32 Width, Uint32 Height, TEXTURE_FORMAT Fmt
         GenerateCheckerBoardPatternInternal(Width, Height, Fmt, HorzCells, VertCells, pData, StrideInBytes, 
             [](Uint8 *pDstTexel, Uint32 NumComponents, float fVal)
             {
-                Uint8 uVal = static_cast<Uint8>(  LinearToSRGB(fVal) * 255.f);
+                Uint8 uVal = static_cast<Uint8>(  FastLinearToSRGB(fVal) * 255.f);
                 for (Uint32 c = 0; c < NumComponents; ++c)
                     pDstTexel[c] = uVal;
             });