three.js/examples/js/postprocessing/TAARenderPass.js

( function () {

	/**
 *
 * Temporal Anti-Aliasing Render Pass
 *
 * When there is no motion in the scene, the TAA render pass accumulates jittered camera samples across frames to create a high quality anti-aliased result.
 *
 * References:
 *
 * TODO: Add support for motion vector pas so that accumulation of samples across frames can occur on dynamics scenes.
 *
 */

	var TAARenderPass = function ( scene, camera, clearColor, clearAlpha ) {

		if ( THREE.SSAARenderPass === undefined ) {

			console.error( 'THREE.TAARenderPass relies on THREE.SSAARenderPass' );

		}

		THREE.SSAARenderPass.call( this, scene, camera, clearColor, clearAlpha );
		this.sampleLevel = 0;
		this.accumulate = false;

	};

	TAARenderPass.JitterVectors = THREE.SSAARenderPass.JitterVectors;
	TAARenderPass.prototype = Object.assign( Object.create( THREE.SSAARenderPass.prototype ), {
		constructor: TAARenderPass,
		render: function ( renderer, writeBuffer, readBuffer, deltaTime ) {

			if ( ! this.accumulate ) {

				THREE.SSAARenderPass.prototype.render.call( this, renderer, writeBuffer, readBuffer, deltaTime );
				this.accumulateIndex = - 1;
				return;

			}

			var jitterOffsets = TAARenderPass.JitterVectors[ 5 ];

			if ( ! this.sampleRenderTarget ) {

				this.sampleRenderTarget = new THREE.WebGLRenderTarget( readBuffer.width, readBuffer.height, this.params );
				this.sampleRenderTarget.texture.name = 'TAARenderPass.sample';

			}

			if ( ! this.holdRenderTarget ) {

				this.holdRenderTarget = new THREE.WebGLRenderTarget( readBuffer.width, readBuffer.height, this.params );
				this.holdRenderTarget.texture.name = 'TAARenderPass.hold';

			}

			if ( this.accumulate && this.accumulateIndex === - 1 ) {

				THREE.SSAARenderPass.prototype.render.call( this, renderer, this.holdRenderTarget, readBuffer, deltaTime );
				this.accumulateIndex = 0;

			}

			var autoClear = renderer.autoClear;
			renderer.autoClear = false;
			var sampleWeight = 1.0 / jitterOffsets.length;

			if ( this.accumulateIndex >= 0 && this.accumulateIndex < jitterOffsets.length ) {

				this.copyUniforms[ 'opacity' ].value = sampleWeight;
				this.copyUniforms[ 'tDiffuse' ].value = writeBuffer.texture; // render the scene multiple times, each slightly jitter offset from the last and accumulate the results.

				var numSamplesPerFrame = Math.pow( 2, this.sampleLevel );

				for ( var i = 0; i < numSamplesPerFrame; i ++ ) {

					var j = this.accumulateIndex;
					var jitterOffset = jitterOffsets[ j ];

					if ( this.camera.setViewOffset ) {

						this.camera.setViewOffset( readBuffer.width, readBuffer.height, jitterOffset[ 0 ] * 0.0625, jitterOffset[ 1 ] * 0.0625, // 0.0625 = 1 / 16
							readBuffer.width, readBuffer.height );

					}

					renderer.setRenderTarget( writeBuffer );
					renderer.clear();
					renderer.render( this.scene, this.camera );
					renderer.setRenderTarget( this.sampleRenderTarget );
					if ( this.accumulateIndex === 0 ) renderer.clear();
					this.fsQuad.render( renderer );
					this.accumulateIndex ++;
					if ( this.accumulateIndex >= jitterOffsets.length ) break;

				}

				if ( this.camera.clearViewOffset ) this.camera.clearViewOffset();

			}

			var accumulationWeight = this.accumulateIndex * sampleWeight;

			if ( accumulationWeight > 0 ) {

				this.copyUniforms[ 'opacity' ].value = 1.0;
				this.copyUniforms[ 'tDiffuse' ].value = this.sampleRenderTarget.texture;
				renderer.setRenderTarget( writeBuffer );
				renderer.clear();
				this.fsQuad.render( renderer );

			}

			if ( accumulationWeight < 1.0 ) {

				this.copyUniforms[ 'opacity' ].value = 1.0 - accumulationWeight;
				this.copyUniforms[ 'tDiffuse' ].value = this.holdRenderTarget.texture;
				renderer.setRenderTarget( writeBuffer );
				if ( accumulationWeight === 0 ) renderer.clear();
				this.fsQuad.render( renderer );

			}

			renderer.autoClear = autoClear;

		}
	} );

	THREE.TAARenderPass = TAARenderPass;

} )();