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@@ -29,6 +29,7 @@ class SSAARenderPass extends Pass {
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this.camera = camera;
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this.sampleLevel = 4; // specified as n, where the number of samples is 2^n, so sampleLevel = 4, is 2^4 samples, 16.
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+ this.unbiased = true;
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// as we need to clear the buffer in this pass, clearColor must be set to something, defaults to black.
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this.clearColor = ( clearColor !== undefined ) ? clearColor : 0x000000;
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@@ -91,6 +92,8 @@ class SSAARenderPass extends Pass {
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renderer.getClearColor( this._oldClearColor );
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const oldClearAlpha = renderer.getClearAlpha();
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+ const baseSampleWeight = 1.0 / jitterOffsets.length;
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+ const roundingRange = 1 / 32;
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this.copyUniforms[ 'tDiffuse' ].value = this.sampleRenderTarget.texture;
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const viewOffset = {
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@@ -127,7 +130,20 @@ class SSAARenderPass extends Pass {
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}
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- this.copyUniforms[ 'opacity' ].value = 1.0 / jitterOffsets.length;
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+ let sampleWeight = baseSampleWeight;
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+
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+ if ( this.unbiased ) {
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+
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+ // the theory is that equal weights for each sample lead to an accumulation of rounding errors.
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+ // The following equation varies the sampleWeight per sample so that it is uniformly distributed
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+ // across a range of values whose rounding errors cancel each other out.
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+
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+ const uniformCenteredDistribution = ( - 0.5 + ( i + 0.5 ) / jitterOffsets.length );
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+ sampleWeight += roundingRange * uniformCenteredDistribution;
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+
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+ }
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+
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+ this.copyUniforms[ 'opacity' ].value = sampleWeight;
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renderer.setClearColor( this.clearColor, this.clearAlpha );
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renderer.setRenderTarget( this.sampleRenderTarget );
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renderer.clear();
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Michael Herzog