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* replace stratified sampling with halton sampling * experiment with random texture * remove stratified sampling files * remove texture experiments * divide instead of multiply to fix precision bug * combine stratified and halton sampling * blue noise (wip) * use white noise for preview * white noise from xorshift instead of texture * optimize setStrataCount * comments and cleanup * include noise texture * remove unneeded line * remove halton sequence code * remove unnecessary shuffle * remove stratifiedRandom array property * rename to stratifiedSampler * rename sceneSampler; add comments
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Lucas
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Sep 11, 2019
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,62 +1,61 @@ | ||
| // Random number generation as described by | ||
| // http://www.reedbeta.com/blog/quick-and-easy-gpu-random-numbers-in-d3d11/ | ||
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| export default function(params) { | ||
| return ` | ||
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| // higher quality but slower hashing function | ||
| uint wangHash(uint x) { | ||
| x = (x ^ 61u) ^ (x >> 16u); | ||
| x *= 9u; | ||
| x = x ^ (x >> 4u); | ||
| x *= 0x27d4eb2du; | ||
| x = x ^ (x >> 15u); | ||
| return x; | ||
| } | ||
| // Noise texture used to generate a different random number for each pixel. | ||
| // We use blue noise in particular, but any type of noise will work. | ||
| uniform sampler2D noise; | ||
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| uniform float stratifiedSamples[SAMPLING_DIMENSIONS]; | ||
| uniform float strataSize; | ||
| uniform float useStratifiedSampling; | ||
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| // Every time we call randomSample() in the shader, and for every call to render, | ||
| // we want that specific bit of the shader to fetch a sample from the same position in stratifiedSamples | ||
| // This allows us to use stratified sampling for each random variable in our path tracing | ||
| int sampleIndex = 0; | ||
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| const highp float maxUint = 1.0 / 4294967295.0; | ||
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| float pixelSeed; | ||
| highp uint randState; | ||
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| // lower quality but faster hashing function | ||
| // simple integer hashing function | ||
| // https://en.wikipedia.org/wiki/Xorshift | ||
| uint xorshift(uint x) { | ||
| x ^= x << 13u; | ||
| x ^= x >> 17u; | ||
| x ^= x << 5u; | ||
| return x; | ||
| } | ||
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| uniform float seed; // Random number [0, 1) | ||
| uniform float strataStart[STRATA_DIMENSIONS]; | ||
| uniform float strataSize; | ||
| void initRandom() { | ||
| vec2 noiseSize = vec2(textureSize(noise, 0)); | ||
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| const highp float maxUint = 1.0 / 4294967295.0; | ||
| highp uint randState; | ||
| int strataDimension; | ||
| // tile the small noise texture across the entire screen | ||
| pixelSeed = texture(noise, vCoord / (pixelSize * noiseSize)).r; | ||
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| // init state with high quality hashing function to avoid patterns across the 2d image | ||
| void initRandom() { | ||
| randState = wangHash(floatBitsToUint(seed)); | ||
| randState *= wangHash(floatBitsToUint(vCoord.x)); | ||
| randState *= wangHash(floatBitsToUint(vCoord.y)); | ||
| randState = wangHash(randState); | ||
| strataDimension = 0; | ||
| // white noise used if stratified sampling is disabled | ||
| // produces more balanced path tracing for 1 sample-per-pixel renders | ||
| randState = xorshift(xorshift(floatBitsToUint(vCoord.x)) * xorshift(floatBitsToUint(vCoord.y))); | ||
| } | ||
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| float random() { | ||
| float randomSample() { | ||
| randState = xorshift(randState); | ||
| float f = float(randState) * maxUint; | ||
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| // transform random number between [0, 1] to (0, 1) | ||
| return EPS + (1.0 - 2.0 * EPS) * f; | ||
| } | ||
| float stratifiedSample = stratifiedSamples[sampleIndex++]; | ||
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| vec2 randomVec2() { | ||
| return vec2(random(), random()); | ||
| } | ||
| float random = mix( | ||
| float(randState) * maxUint, // white noise | ||
| fract((stratifiedSample + pixelSeed) * strataSize), // blue noise + stratified samples | ||
| useStratifiedSampling | ||
| ); | ||
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| float randomStrata() { | ||
| return strataStart[strataDimension++] + strataSize * random(); | ||
| // transform random number between [0, 1] to (0, 1) | ||
| return EPS + (1.0 - 2.0 * EPS) * random; | ||
| } | ||
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| vec2 randomStrataVec2() { | ||
| return vec2(randomStrata(), randomStrata()); | ||
| vec2 randomSampleVec2() { | ||
| return vec2(randomSample(), randomSample()); | ||
| } | ||
| `; | ||
| }; |
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