88 lines
2.3 KiB
HLSL
88 lines
2.3 KiB
HLSL
static float2 poissonDisk[16] =
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{
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float2( -0.94201624, -0.39906216 ),
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float2( 0.94558609, -0.76890725 ),
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float2( -0.094184101, -0.92938870 ),
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float2( 0.34495938, 0.29387760 ),
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float2( -0.91588581, 0.45771432 ),
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float2( -0.81544232, -0.87912464 ),
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float2( -0.38277543, 0.27676845 ),
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float2( 0.97484398, 0.75648379 ),
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float2( 0.44323325, -0.97511554 ),
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float2( 0.53742981, -0.47373420 ),
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float2( -0.26496911, -0.41893023 ),
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float2( 0.79197514, 0.19090188 ),
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float2( -0.24188840, 0.99706507 ),
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float2( -0.81409955, 0.91437590 ),
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float2( 0.19984126, 0.78641367 ),
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float2( 0.14383161, -0.14100790 )
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};
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// TODO: this should probably sample a noise texture instead
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// Returns a random number based on a vec3 and an int.
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float random(float3 seed, int i){
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float4 seed4 = float4(seed, i);
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float dot_product = dot(seed4, float4(12.9898,78.233,45.164,94.673));
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return frac(sin(dot_product) * 43758.5453);
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}
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float PoissonCoord(sampler shadowMap, float3 worldPosition, float2 texCoord, float fragmentDepth, float bias)
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{
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float visibility = 1.0;
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for (int i = 0; i < 16; i++)
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{
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int index = int(16.0 * random(floor(worldPosition * 1000.0), i)) % 16;
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if (tex2D(shadowMap, texCoord + poissonDisk[index] / 1024.0).r < fragmentDepth - bias)
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{
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visibility -= 0.05;
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}
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}
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return visibility;
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}
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float PoissonShadow(
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float3 positionWorldSpace,
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float3 N,
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float3 L,
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float4x4 lightSpaceMatrix,
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sampler shadowMap,
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int shadowMapSize
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) {
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float bias = 0.005 * tan(acos(dot(N, L)));
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bias = clamp(bias, 0, 0.01);
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float4 positionLightSpace = mul(float4(positionWorldSpace, 1.0), lightSpaceMatrix);
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// maps to [-1, 1]
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float3 projectionCoords = positionLightSpace.xyz / positionLightSpace.w;
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// maps to [0, 1]
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// NOTE: In XNA, clip space z is [0, 1] range
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projectionCoords.x = (projectionCoords.x * 0.5) + 0.5;
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projectionCoords.y = (projectionCoords.y * 0.5) + 0.5;
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projectionCoords.y *= -1;
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if (projectionCoords.z > 1.0)
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{
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return 1.0;
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}
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float inc = 1.0 / shadowMapSize;
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// Poisson soft shadows
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float visibility = 0.0;
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visibility = PoissonCoord(
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shadowMap,
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positionWorldSpace,
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projectionCoords.xy,
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projectionCoords.z,
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bias
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);
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return visibility;
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}
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