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

import {
	AdditiveBlending,
	HalfFloatType,
	ShaderMaterial,
	UniformsUtils,
	Vector2,
	WebGLRenderTarget
} from 'three';
import { Pass, FullScreenQuad } from './Pass.js';
import { ConvolutionShader } from '../shaders/ConvolutionShader.js';

class BloomPass extends Pass {

	constructor( strength = 1, kernelSize = 25, sigma = 4 ) {

		super();

		// render targets

		this.renderTargetX = new WebGLRenderTarget( 1, 1, { type: HalfFloatType } ); // will be resized later
		this.renderTargetX.texture.name = 'BloomPass.x';
		this.renderTargetY = new WebGLRenderTarget( 1, 1, { type: HalfFloatType } ); // will be resized later
		this.renderTargetY.texture.name = 'BloomPass.y';

		// combine material

		this.combineUniforms = UniformsUtils.clone( CombineShader.uniforms );

		this.combineUniforms[ 'strength' ].value = strength;

		this.materialCombine = new ShaderMaterial( {

			name: CombineShader.name,
			uniforms: this.combineUniforms,
			vertexShader: CombineShader.vertexShader,
			fragmentShader: CombineShader.fragmentShader,
			blending: AdditiveBlending,
			transparent: true

		} );

		// convolution material

		const convolutionShader = ConvolutionShader;

		this.convolutionUniforms = UniformsUtils.clone( convolutionShader.uniforms );

		this.convolutionUniforms[ 'uImageIncrement' ].value = BloomPass.blurX;
		this.convolutionUniforms[ 'cKernel' ].value = ConvolutionShader.buildKernel( sigma );

		this.materialConvolution = new ShaderMaterial( {

			name: convolutionShader.name,
			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 FullScreenQuad( null );

	}

	render( 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.materialCombine;

		this.combineUniforms[ '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 );

	}

	setSize( width, height ) {

		this.renderTargetX.setSize( width, height );
		this.renderTargetY.setSize( width, height );

	}

	dispose() {

		this.renderTargetX.dispose();
		this.renderTargetY.dispose();

		this.materialCombine.dispose();
		this.materialConvolution.dispose();

		this.fsQuad.dispose();

	}

}

const CombineShader = {

	name: 'CombineShader',

	uniforms: {

		'tDiffuse': { value: null },
		'strength': { value: 1.0 }

	},

	vertexShader: /* glsl */`

		varying vec2 vUv;

		void main() {

			vUv = uv;
			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,

	fragmentShader: /* glsl */`

		uniform float strength;

		uniform sampler2D tDiffuse;

		varying vec2 vUv;

		void main() {

			vec4 texel = texture2D( tDiffuse, vUv );
			gl_FragColor = strength * texel;

		}`

};

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

export { BloomPass };