From 9d3fe69b9859c64c1603aec713acf6c66410b202 Mon Sep 17 00:00:00 2001
From: papadanku <pauldang2@gmail.com>
Date: Fri, 28 Jun 2024 14:45:43 -0700
Subject: [PATCH] Update cTonemap.fxh

---
 shaders/shared/cTonemap.fxh | 83 +++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)

diff --git a/shaders/shared/cTonemap.fxh b/shaders/shared/cTonemap.fxh
index e69de29..574ab6f 100644
--- a/shaders/shared/cTonemap.fxh
+++ b/shaders/shared/cTonemap.fxh
@@ -0,0 +1,83 @@
+
+/*
+    The MIT License (MIT)
+
+    Copyright (c) 2015 Microsoft
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    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. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE.
+*/
+
+#if !defined(INCLUDE_TONEMAP)
+    #define INCLUDE_TONEMAP
+
+    /*
+        The Reinhard tone operator. Typically, the value of K is 1.0, but you can adjust exposure by 1/K.
+        I.e. ApplyReinhardTonemap(x, 0.5) == ApplyReinhardTonemap(x * 2.0, 1.0)
+    */
+
+    float3 ApplyReinhardTonemap(float3 HDR, float K)
+    {
+        return HDR / (HDR + K);
+    }
+
+    // The inverse of Reinhard
+    float3 ApplyInverseReinhardTonemap(float3 SDR, float K)
+    {
+        return K * SDR / (K - SDR);
+    }
+
+    /*
+        This is the new tone operator. It resembles ACES in many ways, but it is simpler to evaluate with ALU. One advantage it has over Reinhard-Squared is that the shoulder goes to white more quickly and gives more overall brightness and contrast to the image.
+    */
+
+    float3 ApplyNewToneMap(float3 HDR)
+    {
+        return ApplyReinhardTonemap(HDR * sqrt(HDR), sqrt(4.0 / 27.0));
+    }
+
+    float3 ApplyInverseNewToneMap(float3 SDR)
+    {
+        return pow(ApplyInverseReinhardTonemap(SDR, sqrt(4.0 / 27.0)), 2.0 / 3.0);
+    }
+
+    /*
+        ACES: The next generation of filmic tone operators.
+    */
+
+    float3 ApplyToneMapACES(float3 HDR)
+    {
+        const float A = 2.51;
+        const float B = 0.03;
+        const float C = 2.43;
+        const float D = 0.59;
+        const float E = 0.14;
+        return saturate((HDR * (A * HDR + B)) / (HDR * (C * HDR + D) + E));
+    }
+
+    float3 ApplyInverseToneMapACES(float3 SDR)
+    {
+        const float A = 2.51;
+        const float B = 0.03;
+        const float C = 2.43;
+        const float D = 0.59;
+        const float E = 0.14;
+        return 0.5 * (D * SDR - sqrt(((D*D - 4.0*C*E) * SDR + 4.0*A*E-2.0*B*D) * SDR + B*B) - B) / (A - C * SDR);
+    }
+
+#endif