three 基础库
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( function () {
/**
*
* Supersample Anti-Aliasing Render THREE.Pass
*
* This manual approach to SSAA re-renders the scene ones for each sample with camera jitter and accumulates the results.
*
* References: https://en.wikipedia.org/wiki/Supersampling
*
*/
class SSAARenderPass extends THREE.Pass {
constructor( scene, camera, clearColor, clearAlpha ) {
super();
this.scene = scene;
this.camera = camera;
this.sampleLevel = 4; // specified as n, where the number of samples is 2^n, so sampleLevel = 4, is 2^4 samples, 16.
this.unbiased = true; // as we need to clear the buffer in this pass, clearColor must be set to something, defaults to black.
this.clearColor = clearColor !== undefined ? clearColor : 0x000000;
this.clearAlpha = clearAlpha !== undefined ? clearAlpha : 0;
this._oldClearColor = new THREE.Color();
if ( THREE.CopyShader === undefined ) console.error( 'THREE.SSAARenderPass relies on THREE.CopyShader' );
const copyShader = THREE.CopyShader;
this.copyUniforms = THREE.UniformsUtils.clone( copyShader.uniforms );
this.copyMaterial = new THREE.ShaderMaterial( {
uniforms: this.copyUniforms,
vertexShader: copyShader.vertexShader,
fragmentShader: copyShader.fragmentShader,
premultipliedAlpha: true,
transparent: true,
blending: THREE.AdditiveBlending,
depthTest: false,
depthWrite: false
} );
this.fsQuad = new THREE.FullScreenQuad( this.copyMaterial );
}
dispose() {
if ( this.sampleRenderTarget ) {
this.sampleRenderTarget.dispose();
this.sampleRenderTarget = null;
}
}
setSize( width, height ) {
if ( this.sampleRenderTarget ) this.sampleRenderTarget.setSize( width, height );
}
render( renderer, writeBuffer, readBuffer ) {
if ( ! this.sampleRenderTarget ) {
this.sampleRenderTarget = new THREE.WebGLRenderTarget( readBuffer.width, readBuffer.height, {
minFilter: THREE.LinearFilter,
magFilter: THREE.LinearFilter,
format: THREE.RGBAFormat
} );
this.sampleRenderTarget.texture.name = 'SSAARenderPass.sample';
}
const jitterOffsets = _JitterVectors[ Math.max( 0, Math.min( this.sampleLevel, 5 ) ) ];
const autoClear = renderer.autoClear;
renderer.autoClear = false;
renderer.getClearColor( this._oldClearColor );
const oldClearAlpha = renderer.getClearAlpha();
const baseSampleWeight = 1.0 / jitterOffsets.length;
const roundingRange = 1 / 32;
this.copyUniforms[ 'tDiffuse' ].value = this.sampleRenderTarget.texture;
const viewOffset = {
fullWidth: readBuffer.width,
fullHeight: readBuffer.height,
offsetX: 0,
offsetY: 0,
width: readBuffer.width,
height: readBuffer.height
};
const originalViewOffset = Object.assign( {}, this.camera.view );
if ( originalViewOffset.enabled ) Object.assign( viewOffset, originalViewOffset ); // render the scene multiple times, each slightly jitter offset from the last and accumulate the results.
for ( let i = 0; i < jitterOffsets.length; i ++ ) {
const jitterOffset = jitterOffsets[ i ];
if ( this.camera.setViewOffset ) {
this.camera.setViewOffset( viewOffset.fullWidth, viewOffset.fullHeight, viewOffset.offsetX + jitterOffset[ 0 ] * 0.0625, viewOffset.offsetY + jitterOffset[ 1 ] * 0.0625, // 0.0625 = 1 / 16
viewOffset.width, viewOffset.height );
}
let sampleWeight = baseSampleWeight;
if ( this.unbiased ) {
// the theory is that equal weights for each sample lead to an accumulation of rounding errors.
// The following equation varies the sampleWeight per sample so that it is uniformly distributed
// across a range of values whose rounding errors cancel each other out.
const uniformCenteredDistribution = - 0.5 + ( i + 0.5 ) / jitterOffsets.length;
sampleWeight += roundingRange * uniformCenteredDistribution;
}
this.copyUniforms[ 'opacity' ].value = sampleWeight;
renderer.setClearColor( this.clearColor, this.clearAlpha );
renderer.setRenderTarget( this.sampleRenderTarget );
renderer.clear();
renderer.render( this.scene, this.camera );
renderer.setRenderTarget( this.renderToScreen ? null : writeBuffer );
if ( i === 0 ) {
renderer.setClearColor( 0x000000, 0.0 );
renderer.clear();
}
this.fsQuad.render( renderer );
}
if ( this.camera.setViewOffset && originalViewOffset.enabled ) {
this.camera.setViewOffset( originalViewOffset.fullWidth, originalViewOffset.fullHeight, originalViewOffset.offsetX, originalViewOffset.offsetY, originalViewOffset.width, originalViewOffset.height );
} else if ( this.camera.clearViewOffset ) {
this.camera.clearViewOffset();
}
renderer.autoClear = autoClear;
renderer.setClearColor( this._oldClearColor, oldClearAlpha );
}
} // These jitter vectors are specified in integers because it is easier.
// I am assuming a [-8,8) integer grid, but it needs to be mapped onto [-0.5,0.5)
// before being used, thus these integers need to be scaled by 1/16.
//
// Sample patterns reference: https://msdn.microsoft.com/en-us/library/windows/desktop/ff476218%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396
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 ]]];
THREE.SSAARenderPass = SSAARenderPass;
} )();