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91 行
3.1 KiB
91 行
3.1 KiB
#ifndef UNITY_COMMON_LIGHTING_INCLUDED
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#define UNITY_COMMON_LIGHTING_INCLUDED
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// Ligthing convention
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// Light direction is oriented backward (-Z). i.e in shader code, light direction is -lightData.forward
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//-----------------------------------------------------------------------------
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// Attenuation functions
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//-----------------------------------------------------------------------------
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// Ref: Moving Frostbite to PBR
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float SmoothDistanceAttenuation(float squaredDistance, float invSqrAttenuationRadius)
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{
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float factor = squaredDistance * invSqrAttenuationRadius;
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float smoothFactor = saturate(1.0f - factor * factor);
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return smoothFactor * smoothFactor;
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}
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#define PUNCTUAL_LIGHT_THRESHOLD 0.01 // 1cm (in Unity 1 is 1m)
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float GetDistanceAttenuation(float3 unL, float invSqrAttenuationRadius)
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{
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float sqrDist = dot(unL, unL);
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float attenuation = 1.0f / (max(PUNCTUAL_LIGHT_THRESHOLD * PUNCTUAL_LIGHT_THRESHOLD, sqrDist));
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// Non physically based hack to limit light influence to attenuationRadius.
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attenuation *= SmoothDistanceAttenuation(sqrDist, invSqrAttenuationRadius);
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return attenuation;
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}
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float GetAngleAttenuation(float3 L, float3 lightDir, float lightAngleScale, float lightAngleOffset)
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{
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float cd = dot(lightDir, L);
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float attenuation = saturate(cd * lightAngleScale + lightAngleOffset);
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// smooth the transition
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attenuation *= attenuation;
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return attenuation;
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}
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//-----------------------------------------------------------------------------
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// IES Helper
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//-----------------------------------------------------------------------------
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float2 GetIESTextureCoordinate(float3x3 lightToWord, float3 L)
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{
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// IES need to be sample in light space
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float3 dir = mul(lightToWord, -L); // Using matrix on left side do a transpose
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// convert to spherical coordinate
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float2 sphericalCoord; // .x is theta, .y is phi
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// Texture is encoded with cos(phi), scale from -1..1 to 0..1
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sphericalCoord.y = (dir.z * 0.5) + 0.5;
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float theta = atan2(dir.y, dir.x);
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sphericalCoord.x = theta * INV_TWO_PI;
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return sphericalCoord;
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}
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//-----------------------------------------------------------------------------
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// Get local frame
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//-----------------------------------------------------------------------------
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// generate an orthonormalBasis from 3d unit vector.
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void GetLocalFrame(float3 N, out float3 tangentX, out float3 tangentY)
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{
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float3 upVector = abs(N.z) < 0.999 ? float3(0.0, 0.0, 1.0) : float3(1.0, 0.0, 0.0);
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tangentX = normalize(cross(upVector, N));
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tangentY = cross(N, tangentX);
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}
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// TODO: test
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/*
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// http://orbit.dtu.dk/files/57573287/onb_frisvad_jgt2012.pdf
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void GetLocalFrame(float3 N, out float3 tangentX, out float3 tangentY)
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{
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if (N.z < -0.999) // Handle the singularity
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{
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tangentX = float3(0.0, -1.0, 0.0);
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tangentY = float3(-1.0, 0.0, 0.0);
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return ;
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}
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float a = 1.0 / (1.0 + N.z);
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float b = -N.x * N.y * a;
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tangentX = float3(1.0f - N.x * N.x * a , b, -N.x);
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tangentY = float3(b, 1.0f - N.y * N.y * a, -N.y);
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}
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*/
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#endif // UNITY_COMMON_LIGHTING_INCLUDED
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