From 1d4bc9377fe3920a602bc61b0dc96c82f1a9ed66 Mon Sep 17 00:00:00 2001
From: Michael Fabian 'Xaymar' Dirks <info@xaymar.com>
Date: Thu, 25 Nov 2021 10:02:45 +0100
Subject: [PATCH] examples: Add RGB<->YUV color conversion shader

---
 .../shaders/colorconversion_rgb_yuv.effect    | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 data/examples/shaders/colorconversion_rgb_yuv.effect

diff --git a/data/examples/shaders/colorconversion_rgb_yuv.effect b/data/examples/shaders/colorconversion_rgb_yuv.effect
new file mode 100644
index 00000000..9823037b
--- /dev/null
+++ b/data/examples/shaders/colorconversion_rgb_yuv.effect
@@ -0,0 +1,74 @@
+// Copyright 2021 Michael Fabian Dirks <info@xaymar.com>
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice,
+//    this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright notice,
+//    this list of conditions and the following disclaimer in the documentation
+//    and/or other materials provided with the distribution.
+// 3. Neither the name of the copyright holder nor the names of its contributors
+//    may be used to endorse or promote products derived from this software
+//    without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+// ================================================================================ //
+// Matrices
+// ================================================================================ //
+
+#define RGB_YUV_709 float3x3( 0.21260,  0.71520,  0.07220,\
+                             -0.11457, -0.38543,  0.50000,\
+                              0.50000, -0.45415, -0.04585)
+#define YUV_709_RGB float3x3( 1.00000,  0.00000,  1.57480,\
+                              1.00000, -0.18732, -0.46812,\
+                              1.00000,  1.85560,  0.00000)
+
+// ================================================================================ //
+// Functions: Balanced Color Conversion
+// ================================================================================ //
+float3 RGBtoYUV(float3 rgb, float3x3 m) {
+	return mul(m, rgb) + float3(0, .5, .5);
+}
+
+float4 RGBAtoYUVA(float4 rgba, float3x3 m) {
+	return float4(RGBtoYUV(rgba.rgb, m), rgba.a);
+}
+
+float3 YUVtoRGB(float3 yuv, float3x3 m) {
+	return mul(m, yuv - float3(0, .5, .5));
+}
+
+float4 YUVAtoRGBA(float4 yuva, float3x3 m) {
+	return float4(YUVtoRGB(yuva.rgb, m), yuva.a);
+}
+
+// ================================================================================ //
+// Function: Unbalanced Color Conversion
+// ================================================================================ //
+float3 RGBtoYUVf(float3 rgb, float3x3 m) {
+	return mul(m, rgb);
+}
+
+float4 RGBAtoYUVAf(float4 rgba, float3x3 m) {
+	return float4(RGBtoYUVf(rgba.rgb, m), rgba.a);
+}
+
+float3 YUVtoRGBf(float3 yuv, float3x3 m) {
+	return mul(m, yuv);
+}
+
+float4 YUVAtoRGBAf(float4 yuva, float3x3 m) {
+	return float4(YUVtoRGBf(yuva.rgb, m), yuva.a);
+}