three.js/examples/js/postprocessing/BloomPass.js

( function () {

	var BloomPass = function ( strength, kernelSize, sigma, resolution ) {

		THREE.Pass.call( this );
		strength = strength !== undefined ? strength : 1;
		kernelSize = kernelSize !== undefined ? kernelSize : 25;
		sigma = sigma !== undefined ? sigma : 4.0;
		resolution = resolution !== undefined ? resolution : 256; // render targets

		var pars = {
			minFilter: THREE.LinearFilter,
			magFilter: THREE.LinearFilter,
			format: THREE.RGBAFormat
		};
		this.renderTargetX = new THREE.WebGLRenderTarget( resolution, resolution, pars );
		this.renderTargetX.texture.name = 'BloomPass.x';
		this.renderTargetY = new THREE.WebGLRenderTarget( resolution, resolution, pars );
		this.renderTargetY.texture.name = 'BloomPass.y'; // copy material

		if ( THREE.CopyShader === undefined ) console.error( 'THREE.BloomPass relies on THREE.CopyShader' );
		var copyShader = THREE.CopyShader;
		this.copyUniforms = THREE.UniformsUtils.clone( copyShader.uniforms );
		this.copyUniforms[ 'opacity' ].value = strength;
		this.materialCopy = new THREE.ShaderMaterial( {
			uniforms: this.copyUniforms,
			vertexShader: copyShader.vertexShader,
			fragmentShader: copyShader.fragmentShader,
			blending: THREE.AdditiveBlending,
			transparent: true
		} ); // convolution material

		if ( THREE.ConvolutionShader === undefined ) console.error( 'THREE.BloomPass relies on THREE.ConvolutionShader' );
		var convolutionShader = THREE.ConvolutionShader;
		this.convolutionUniforms = THREE.UniformsUtils.clone( convolutionShader.uniforms );
		this.convolutionUniforms[ 'uImageIncrement' ].value = BloomPass.blurX;
		this.convolutionUniforms[ 'cKernel' ].value = THREE.ConvolutionShader.buildKernel( sigma );
		this.materialConvolution = new THREE.ShaderMaterial( {
			uniforms: this.convolutionUniforms,
			vertexShader: convolutionShader.vertexShader,
			fragmentShader: convolutionShader.fragmentShader,
			defines: {
				'KERNEL_SIZE_FLOAT': kernelSize.toFixed( 1 ),
				'KERNEL_SIZE_INT': kernelSize.toFixed( 0 )
			}
		} );
		this.needsSwap = false;
		this.fsQuad = new THREE.Pass.FullScreenQuad( null );

	};

	BloomPass.prototype = Object.assign( Object.create( THREE.Pass.prototype ), {
		constructor: BloomPass,
		render: function ( renderer, writeBuffer, readBuffer, deltaTime, maskActive ) {

			if ( maskActive ) renderer.state.buffers.stencil.setTest( false ); // Render quad with blured scene into texture (convolution pass 1)

			this.fsQuad.material = this.materialConvolution;
			this.convolutionUniforms[ 'tDiffuse' ].value = readBuffer.texture;
			this.convolutionUniforms[ 'uImageIncrement' ].value = BloomPass.blurX;
			renderer.setRenderTarget( this.renderTargetX );
			renderer.clear();
			this.fsQuad.render( renderer ); // Render quad with blured scene into texture (convolution pass 2)

			this.convolutionUniforms[ 'tDiffuse' ].value = this.renderTargetX.texture;
			this.convolutionUniforms[ 'uImageIncrement' ].value = BloomPass.blurY;
			renderer.setRenderTarget( this.renderTargetY );
			renderer.clear();
			this.fsQuad.render( renderer ); // Render original scene with superimposed blur to texture

			this.fsQuad.material = this.materialCopy;
			this.copyUniforms[ 'tDiffuse' ].value = this.renderTargetY.texture;
			if ( maskActive ) renderer.state.buffers.stencil.setTest( true );
			renderer.setRenderTarget( readBuffer );
			if ( this.clear ) renderer.clear();
			this.fsQuad.render( renderer );

		}
	} );
	BloomPass.blurX = new THREE.Vector2( 0.001953125, 0.0 );
	BloomPass.blurY = new THREE.Vector2( 0.0, 0.001953125 );

	THREE.BloomPass = BloomPass;

} )();