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156 lines
5.8 KiB
156 lines
5.8 KiB
( function () {
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/**
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*
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* Supersample Anti-Aliasing Render THREE.Pass
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*
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* This manual approach to SSAA re-renders the scene ones for each sample with camera jitter and accumulates the results.
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*
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* References: https://en.wikipedia.org/wiki/Supersampling
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*
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*/
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class SSAARenderPass extends THREE.Pass {
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constructor( scene, camera, clearColor, clearAlpha ) {
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super();
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this.scene = scene;
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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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this.clearAlpha = clearAlpha !== undefined ? clearAlpha : 0;
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this._oldClearColor = new THREE.Color();
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if ( THREE.CopyShader === undefined ) console.error( 'THREE.SSAARenderPass relies on THREE.CopyShader' );
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const copyShader = THREE.CopyShader;
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this.copyUniforms = THREE.UniformsUtils.clone( copyShader.uniforms );
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this.copyMaterial = new THREE.ShaderMaterial( {
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uniforms: this.copyUniforms,
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vertexShader: copyShader.vertexShader,
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fragmentShader: copyShader.fragmentShader,
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transparent: true,
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blending: THREE.AdditiveBlending,
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depthTest: false,
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depthWrite: false
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} );
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this.fsQuad = new THREE.FullScreenQuad( this.copyMaterial );
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}
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dispose() {
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if ( this.sampleRenderTarget ) {
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this.sampleRenderTarget.dispose();
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this.sampleRenderTarget = null;
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}
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this.copyMaterial.dispose();
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this.fsQuad.dispose();
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}
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setSize( width, height ) {
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if ( this.sampleRenderTarget ) this.sampleRenderTarget.setSize( width, height );
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}
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render( renderer, writeBuffer, readBuffer ) {
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if ( ! this.sampleRenderTarget ) {
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this.sampleRenderTarget = new THREE.WebGLRenderTarget( readBuffer.width, readBuffer.height );
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this.sampleRenderTarget.texture.name = 'SSAARenderPass.sample';
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}
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const jitterOffsets = _JitterVectors[ Math.max( 0, Math.min( this.sampleLevel, 5 ) ) ];
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const autoClear = renderer.autoClear;
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renderer.autoClear = false;
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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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fullWidth: readBuffer.width,
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fullHeight: readBuffer.height,
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offsetX: 0,
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offsetY: 0,
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width: readBuffer.width,
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height: readBuffer.height
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};
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const originalViewOffset = Object.assign( {}, this.camera.view );
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if ( originalViewOffset.enabled ) Object.assign( viewOffset, originalViewOffset );
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// render the scene multiple times, each slightly jitter offset from the last and accumulate the results.
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for ( let i = 0; i < jitterOffsets.length; i ++ ) {
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const jitterOffset = jitterOffsets[ i ];
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if ( this.camera.setViewOffset ) {
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this.camera.setViewOffset( viewOffset.fullWidth, viewOffset.fullHeight, viewOffset.offsetX + jitterOffset[ 0 ] * 0.0625, viewOffset.offsetY + jitterOffset[ 1 ] * 0.0625,
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// 0.0625 = 1 / 16
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viewOffset.width, viewOffset.height );
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}
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let sampleWeight = baseSampleWeight;
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if ( this.unbiased ) {
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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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const uniformCenteredDistribution = - 0.5 + ( i + 0.5 ) / jitterOffsets.length;
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sampleWeight += roundingRange * uniformCenteredDistribution;
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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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renderer.render( this.scene, this.camera );
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renderer.setRenderTarget( this.renderToScreen ? null : writeBuffer );
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if ( i === 0 ) {
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renderer.setClearColor( 0x000000, 0.0 );
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renderer.clear();
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}
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this.fsQuad.render( renderer );
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}
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if ( this.camera.setViewOffset && originalViewOffset.enabled ) {
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this.camera.setViewOffset( originalViewOffset.fullWidth, originalViewOffset.fullHeight, originalViewOffset.offsetX, originalViewOffset.offsetY, originalViewOffset.width, originalViewOffset.height );
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} else if ( this.camera.clearViewOffset ) {
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this.camera.clearViewOffset();
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}
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renderer.autoClear = autoClear;
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renderer.setClearColor( this._oldClearColor, oldClearAlpha );
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}
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}
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// These jitter vectors are specified in integers because it is easier.
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// I am assuming a [-8,8) integer grid, but it needs to be mapped onto [-0.5,0.5)
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// before being used, thus these integers need to be scaled by 1/16.
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//
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// Sample patterns reference: https://msdn.microsoft.com/en-us/library/windows/desktop/ff476218%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396
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const _JitterVectors = [[[ 0, 0 ]], [[ 4, 4 ], [ - 4, - 4 ]], [[ - 2, - 6 ], [ 6, - 2 ], [ - 6, 2 ], [ 2, 6 ]], [[ 1, - 3 ], [ - 1, 3 ], [ 5, 1 ], [ - 3, - 5 ], [ - 5, 5 ], [ - 7, - 1 ], [ 3, 7 ], [ 7, - 7 ]], [[ 1, 1 ], [ - 1, - 3 ], [ - 3, 2 ], [ 4, - 1 ], [ - 5, - 2 ], [ 2, 5 ], [ 5, 3 ], [ 3, - 5 ], [ - 2, 6 ], [ 0, - 7 ], [ - 4, - 6 ], [ - 6, 4 ], [ - 8, 0 ], [ 7, - 4 ], [ 6, 7 ], [ - 7, - 8 ]], [[ - 4, - 7 ], [ - 7, - 5 ], [ - 3, - 5 ], [ - 5, - 4 ], [ - 1, - 4 ], [ - 2, - 2 ], [ - 6, - 1 ], [ - 4, 0 ], [ - 7, 1 ], [ - 1, 2 ], [ - 6, 3 ], [ - 3, 3 ], [ - 7, 6 ], [ - 3, 6 ], [ - 5, 7 ], [ - 1, 7 ], [ 5, - 7 ], [ 1, - 6 ], [ 6, - 5 ], [ 4, - 4 ], [ 2, - 3 ], [ 7, - 2 ], [ 1, - 1 ], [ 4, - 1 ], [ 2, 1 ], [ 6, 2 ], [ 0, 4 ], [ 4, 4 ], [ 2, 5 ], [ 7, 5 ], [ 5, 6 ], [ 3, 7 ]]];
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THREE.SSAARenderPass = SSAARenderPass;
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} )();
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