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Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Utility/Helpers.hlsl

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+// Crest Water System
+// Copyright © 2024 Wave Harmonic. All rights reserved.
+
+#ifndef d_WaveHarmonic_Utility_Helpers
+#define d_WaveHarmonic_Utility_Helpers
+
+#include "Packages/com.waveharmonic.crest/Runtime/Shaders/Library/Utility/Macros.hlsl"
+
+m_UtilityNameSpace
+
+void Swap(inout float a, inout float b)
+{
+    float t = a; a = b; b = t;
+}
+
+// Adapted from:
+// https://alex.vlachos.com/graphics/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf
+float3 ScreenSpaceDither(const float2 i_ScreenPosition)
+{
+    // Iestyn's RGB dither (7 asm instructions) from Portal 2 X360, slightly modified for VR.
+    float3 dither = dot(float2(171.0, 231.0), i_ScreenPosition.xy);
+    dither.rgb = frac(dither.rgb / float3(103.0, 71.0, 97.0)) - float3(0.5, 0.5, 0.5);
+    return (dither.rgb / 255.0);
+}
+
+float2 WorldNormalToScreenDirection(const float3 i_PositionWS, const float3 i_NormalWS, const float4x4 i_MatrixVP, const float i_Offset)
+{
+    const float3 p0 = i_PositionWS;
+    const float3 p1 = p0 + i_NormalWS * i_Offset;
+
+    const float4 clip0 = mul(i_MatrixVP, float4(p0, 1));
+    const float4 clip1 = mul(i_MatrixVP, float4(p1, 1));
+
+    const float2 uv0 = (clip0.xy / clip0.w) * 0.5 + 0.5;
+    const float2 uv1 = (clip1.xy / clip1.w) * 0.5 + 0.5;
+
+    float2 direction = normalize(uv1 - uv0);
+
+#if UNITY_UV_STARTS_AT_TOP
+    direction.y = -direction.y;
+#endif
+
+    return direction;
+}
+
+m_UtilityNameSpaceEnd
+
+#endif // d_WaveHarmonic_Utility_Helpers