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