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342 行
11 KiB
342 行
11 KiB
#ifndef UNITY_COMMON_INCLUDED
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#define UNITY_COMMON_INCLUDED
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// Convention:
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// Unity is Y up - left handed
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// space at the end of the variable name
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// WS: world space
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// VS: view space
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// OS: object space
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// CS: Homogenous clip spaces
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// TS: tangent space
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// TXS: texture space
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// Example: NormalWS
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// normalized / unormalized vector
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// normalized direction are almost everywhere, we tag unormalized vector with un.
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// Example: unL for unormalized light vector
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// use capital letter for regular vector, vector are always pointing outward the current pixel position (ready for lighting equation)
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// capital letter mean the vector is normalize, unless we put un in front of it.
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// V: View vector (no eye vector)
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// L: Light vector
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// N: Normal vector
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// H: Half vector
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// Input/Outputs structs in PascalCase and prefixed by entry type
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// struct AttributesDefault
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// struct VaryingsDefault
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// use input/output as variable name when using these structures
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// Entry program name
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// VertDefault
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// FragDefault / FragForward / FragDeferred
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// constant floating number written as 1.0 (not 1, not 1.0f, not 1.0h)
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// uniform have _ as prefix + uppercase _LowercaseThenCamelCase
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// Structure definition that are share between C# and hlsl.
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// These structures need to be align on float4 to respectect various packing rules from sahder language.
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// This mean that these structure need to be padded.
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// Do not use "in", only "out" or "inout" as califier, not "inline" keyword either, useless.
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// The lighting code assume that 1 Unity unit (1uu) == 1 meters. This is very important regarding physically based light unit and inverse square attenuation
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// When declaring "out" argument of function, they are always last
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// headers from ShaderLibrary do not include "common.hlsl", this should be included in the .shader using it (or Material.hlsl)
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// Include language header
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#if defined(SHADER_API_D3D11)
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#include "API/D3D11.hlsl"
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#elif defined(SHADER_API_XBOXONE)
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#include "API/D3D11_1.hlsl"
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#else
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#error unsupported shader api
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#endif
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#include "API/Validate.hlsl"
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// ----------------------------------------------------------------------------
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// Common intrinsic (general implementation of intrinsic available on some platform)
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// ----------------------------------------------------------------------------
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#ifndef INTRINSIC_BITFIELD_EXTRACT
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// unsigned integer bit field extract implementation
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uint BitFieldExtract(uint data, uint size, uint offset)
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{
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return (data >> offset) & ((1u << size) - 1u);
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}
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#endif // INTRINSIC_BITFIELD_EXTRACT
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#ifndef INTRINSIC_CLAMP
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// TODO: should we force all clamp to be intrinsic by default ?
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// Some platform have one instruction clamp
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#define Clamp clamp
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#endif // INTRINSIC_CLAMP
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#ifndef INTRINSIC_MED3
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float Med3(float a, float b, float c)
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{
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return Clamp(a, b, c);
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}
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#endif // INTRINSIC_MED3
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#ifndef INTRINSIC_MINMAX3
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float Min3(float a, float b, float c)
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{
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return min(min(a, b), c);
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}
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float2 Min3(float2 a, float2 b, float2 c)
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{
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return min(min(a, b), c);
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}
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float3 Min3(float3 a, float3 b, float3 c)
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{
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return min(min(a, b), c);
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}
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float4 Min3(float4 a, float4 b, float4 c)
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{
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return min(min(a, b), c);
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}
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float Max3(float a, float b, float c)
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{
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return max(max(a, b), c);
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}
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float2 Max3(float2 a, float2 b, float2 c)
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{
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return max(max(a, b), c);
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}
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float3 Max3(float3 a, float3 b, float3 c)
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{
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return max(max(a, b), c);
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}
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float4 Max3(float4 a, float4 b, float4 c)
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{
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return max(max(a, b), c);
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}
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#endif // INTRINSIC_MINMAX3
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#ifndef INTRINSIC_CUBEMAP_FACE_ID
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// TODO: implement this. Is the reference implementation of cubemapID provide by AMD the reverse of our ?
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/*
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float CubemapFaceID(float3 dir)
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{
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float faceID;
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if (abs(dir.z) >= abs(dir.x) && abs(dir.z) >= abs(dir.y))
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{
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faceID = (dir.z < 0.0) ? 5.0 : 4.0;
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}
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else if (abs(dir.y) >= abs(dir.x))
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{
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faceID = (dir.y < 0.0) ? 3.0 : 2.0;
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}
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else
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{
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faceID = (dir.x < 0.0) ? 1.0 : 0.0;
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}
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return faceID;
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}
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*/
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#endif // INTRINSIC_CUBEMAP_FACE_ID
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#define CUBEMAPFACE_POSITIVE_X 0
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#define CUBEMAPFACE_NEGATIVE_X 1
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#define CUBEMAPFACE_POSITIVE_Y 2
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#define CUBEMAPFACE_NEGATIVE_Y 3
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#define CUBEMAPFACE_POSITIVE_Z 4
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#define CUBEMAPFACE_NEGATIVE_Z 5
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void GetCubeFaceID(float3 dir, out int faceIndex)
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{
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// TODO: Use faceID intrinsic on console
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float3 adir = abs(dir);
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// +Z -Z
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faceIndex = dir.z > 0.0f ? CUBEMAPFACE_NEGATIVE_Z : CUBEMAPFACE_POSITIVE_Z;
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// +X -X
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if (adir.x > adir.y && adir.x > adir.z)
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{
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faceIndex = dir.x > 0.0 ? CUBEMAPFACE_NEGATIVE_X : CUBEMAPFACE_POSITIVE_X;
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}
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// +Y -Y
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else if (adir.y > adir.x && adir.y > adir.z)
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{
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faceIndex = dir.y > 0.0 ? CUBEMAPFACE_NEGATIVE_Y : CUBEMAPFACE_POSITIVE_Y;
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}
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}
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// ----------------------------------------------------------------------------
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// Common math definition and fastmath function
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// ----------------------------------------------------------------------------
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#define PI 3.14159265359
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#define TWO_PI 6.28318530718
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#define FOUR_PI 12.56637061436
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#define INV_PI 0.31830988618
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#define INV_TWO_PI 0.15915494309
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#define INV_FOUR_PI 0.07957747155
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#define HALF_PI 1.57079632679
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#define INV_HALF_PI 0.636619772367
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#define FLT_EPSILON 1.192092896e-07f // smallest such that 1.0 + FLT_EPSILON != 1.0
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#define MERGE_NAME(X, Y) X##Y
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// Acos in 14 cycles.
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// Ref: https://seblagarde.wordpress.com/2014/12/01/inverse-trigonometric-functions-gpu-optimization-for-amd-gcn-architecture/
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float FastACos(float inX)
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{
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float x = abs(inX);
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float res = (0.0468878 * x + -0.203471) * x + 1.570796; // p(x)
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res *= sqrt(1.0f - x);
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return (inX >= 0) ? res : PI - res; // Undo range reduction
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}
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// Same cost as Acos + 1 FR
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// Same error
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// input [-1, 1] and output [-PI/2, PI/2]
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float FastASin(float x)
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{
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return HALF_PI - FastACos(x);
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}
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// max absolute error 1.3x10^-3
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// Eberly's odd polynomial degree 5 - respect bounds
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// 4 VGPR, 14 FR (10 FR, 1 QR), 2 scalar
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// input [0, infinity] and output [0, PI/2]
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float FastATanPos(float x)
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{
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float t0 = (x < 1.0) ? x : 1.0 / x;
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float t1 = t0 * t0;
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float poly = 0.0872929;
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poly = -0.301895 + poly * t1;
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poly = 1.0 + poly * t1;
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poly = poly * t0;
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return (x < 1.0) ? poly : HALF_PI - poly;
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}
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// 4 VGPR, 16 FR (12 FR, 1 QR), 2 scalar
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// input [-infinity, infinity] and output [-PI/2, PI/2]
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float FastATan(float x)
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{
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float t0 = FastATanPos(abs(x));
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return (x < 0.0) ? -t0 : t0;
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}
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// Same smoothstep except it assume 0, 1 interval for x
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float smoothstep01(float x)
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{
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return x * x * (3.0 - (2.0 * x));
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}
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// ----------------------------------------------------------------------------
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// World position reconstruction / transformation
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// ----------------------------------------------------------------------------
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struct Coordinate
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{
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// Normalize coordinates
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float2 positionSS;
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// Unormalize coordinates
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int2 unPositionSS;
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};
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// This function is use to provide an easy way to sample into a screen texture, either from a pixel or a compute shaders.
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// This allow to easily share code.
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// If a compute shader call this function unPositionSS is an integer usually calculate like: uint2 unPositionSS = groupId.xy * BLOCK_SIZE + groupThreadId.xy
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// else it is current unormalized screen coordinate like return by VPOS
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Coordinate GetCoordinate(float2 unPositionSS, float2 invScreenSize)
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{
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Coordinate coord;
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coord.positionSS = unPositionSS;
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#if SHADER_STAGE_COMPUTE
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// In case of compute shader an extra half offset is added to the screenPos to shift the integer position to pixel center.
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coord.positionSS.xy += float2(0.5, 0.5);
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#endif
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coord.positionSS *= invScreenSize;
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coord.unPositionSS = int2(unPositionSS);
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return coord;
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}
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// screenPos is screen coordinate in [0..1] (return by Coordinate.positionSS)
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// depth must be the depth from the raw depth buffer. This allow to handle all kind of depth automatically with the inverse view projection matrix.
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// For information. In Unity Depth is always in range 0..1 (even on OpenGL) but can be reversed.
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float3 UnprojectToWorld(float depth, float2 screenPos, float4x4 invViewProjectionMatrix)
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{
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float4 positionCS = float4(screenPos.xy * 2.0 - 1.0, depth, 1.0);
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float4 hpositionWS = mul(invViewProjectionMatrix, positionCS);
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return hpositionWS.xyz / hpositionWS.w;
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}
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// Z buffer to linear 0..1 depth
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float Linear01Depth(float depth, float4 zBufferParam)
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{
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return 1.0 / (zBufferParam.x * depth + zBufferParam.y);
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}
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// Z buffer to linear depth
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float LinearEyeDepth(float depth, float4 zBufferParam)
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{
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return 1.0 / (zBufferParam.z * depth + zBufferParam.w);
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}
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// NdotV should not be negative for visible pixels, but it can happen due to perspective projection and normal mapping + decal
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// In this case this may cause weird artifact.
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// GetNdotV return a 'valid' data
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float GetNdotV(float3 N, float3 V)
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{
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return abs(dot(N, V)); // This abs allow to limit artifact
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}
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// NdotV should not be negative for visible pixels, but it can happen due to perspective projection and normal mapping + decal
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// In this case normal should be modified to become valid (i.e facing camera) and not cause weird artifacts.
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// but this operation adds few ALU and users may not want it. Alternative is to simply take the abs of NdotV (less correct but works too).
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// Note: This code is not compatible with two sided lighting used in SpeedTree (TODO: investigate).
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float GetShiftedNdotV(float3 N, float3 V)
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{
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// The amount we shift the normal toward the view vector is defined by the dot product.
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float shiftAmount = dot(N, V);
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N = shiftAmount < 0.0 ? N + V * (-shiftAmount + 1e-5f) : N;
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N = normalize(N);
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return saturate(dot(N, V)); // TODO: this saturate should not be necessary here
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}
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// Performs the mapping of the vector 'v' located within the cube of dimensions [-r, r]^3
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// to a vector within the sphere of radius 'r', where r = sqrt(r2).
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// Modified version of http://mathproofs.blogspot.com/2005/07/mapping-cube-to-sphere.html
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float3 MapCubeToSphere(float3 v, float r2)
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{
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float3 v2 = v * v;
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float2 vr3 = v2.xy * rcp(3.0 * r2);
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return v * sqrt((float3)r2 - 0.5 * v2.yzx - 0.5 * v2.zxy + vr3.yxx * v2.zzy);
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}
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// Computes the squared magnitude of the vector 'v' after mapping it
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// to a vector within the sphere of radius 'r', where r = sqrt(r2).
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// The vector is originally defined within the cube of dimensions [-r, r]^3.
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// The mapping is performed as per MapCubeToSphere().
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// 'dotV' is the squared magnitude of the vector 'v' prior to the mapping.
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float ComputeCubeToSphereMapSqMagnitude(float3 v, float dotV, float r2)
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{
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float3 v2 = v * v;
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return r2 * dotV - v2.x * v2.y - v2.y * v2.z - v2.z * v2.x + v2.x * v2.y * v2.z * rcp(r2);
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}
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#endif // UNITY_COMMON_INCLUDED
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