three.js/examples/js/objects/Lensflare.js

( function () {

	class Lensflare extends THREE.Mesh {

		constructor() {

			super( Lensflare.Geometry, new THREE.MeshBasicMaterial( {
				opacity: 0,
				transparent: true
			} ) );
			this.isLensflare = true;
			this.type = 'Lensflare';
			this.frustumCulled = false;
			this.renderOrder = Infinity; //

			const positionScreen = new THREE.Vector3();
			const positionView = new THREE.Vector3(); // textures

			const tempMap = new THREE.FramebufferTexture( 16, 16, THREE.RGBAFormat );
			const occlusionMap = new THREE.FramebufferTexture( 16, 16, THREE.RGBAFormat ); // material

			const geometry = Lensflare.Geometry;
			const material1a = new THREE.RawShaderMaterial( {
				uniforms: {
					'scale': {
						value: null
					},
					'screenPosition': {
						value: null
					}
				},
				vertexShader:
      /* glsl */
      `

				precision highp float;

				uniform vec3 screenPosition;
				uniform vec2 scale;

				attribute vec3 position;

				void main() {

					gl_Position = vec4( position.xy * scale + screenPosition.xy, screenPosition.z, 1.0 );

				}`,
				fragmentShader:
      /* glsl */
      `

				precision highp float;

				void main() {

					gl_FragColor = vec4( 1.0, 0.0, 1.0, 1.0 );

				}`,
				depthTest: true,
				depthWrite: false,
				transparent: false
			} );
			const material1b = new THREE.RawShaderMaterial( {
				uniforms: {
					'map': {
						value: tempMap
					},
					'scale': {
						value: null
					},
					'screenPosition': {
						value: null
					}
				},
				vertexShader:
      /* glsl */
      `

				precision highp float;

				uniform vec3 screenPosition;
				uniform vec2 scale;

				attribute vec3 position;
				attribute vec2 uv;

				varying vec2 vUV;

				void main() {

					vUV = uv;

					gl_Position = vec4( position.xy * scale + screenPosition.xy, screenPosition.z, 1.0 );

				}`,
				fragmentShader:
      /* glsl */
      `

				precision highp float;

				uniform sampler2D map;

				varying vec2 vUV;

				void main() {

					gl_FragColor = texture2D( map, vUV );

				}`,
				depthTest: false,
				depthWrite: false,
				transparent: false
			} ); // the following object is used for occlusionMap generation

			const mesh1 = new THREE.Mesh( geometry, material1a ); //

			const elements = [];
			const shader = LensflareElement.Shader;
			const material2 = new THREE.RawShaderMaterial( {
				uniforms: {
					'map': {
						value: null
					},
					'occlusionMap': {
						value: occlusionMap
					},
					'color': {
						value: new THREE.Color( 0xffffff )
					},
					'scale': {
						value: new THREE.Vector2()
					},
					'screenPosition': {
						value: new THREE.Vector3()
					}
				},
				vertexShader: shader.vertexShader,
				fragmentShader: shader.fragmentShader,
				blending: THREE.AdditiveBlending,
				transparent: true,
				depthWrite: false
			} );
			const mesh2 = new THREE.Mesh( geometry, material2 );

			this.addElement = function ( element ) {

				elements.push( element );

			}; //


			const scale = new THREE.Vector2();
			const screenPositionPixels = new THREE.Vector2();
			const validArea = new THREE.Box2();
			const viewport = new THREE.Vector4();

			this.onBeforeRender = function ( renderer, scene, camera ) {

				renderer.getCurrentViewport( viewport );
				const invAspect = viewport.w / viewport.z;
				const halfViewportWidth = viewport.z / 2.0;
				const halfViewportHeight = viewport.w / 2.0;
				let size = 16 / viewport.w;
				scale.set( size * invAspect, size );
				validArea.min.set( viewport.x, viewport.y );
				validArea.max.set( viewport.x + ( viewport.z - 16 ), viewport.y + ( viewport.w - 16 ) ); // calculate position in screen space

				positionView.setFromMatrixPosition( this.matrixWorld );
				positionView.applyMatrix4( camera.matrixWorldInverse );
				if ( positionView.z > 0 ) return; // lensflare is behind the camera

				positionScreen.copy( positionView ).applyMatrix4( camera.projectionMatrix ); // horizontal and vertical coordinate of the lower left corner of the pixels to copy

				screenPositionPixels.x = viewport.x + positionScreen.x * halfViewportWidth + halfViewportWidth - 8;
				screenPositionPixels.y = viewport.y + positionScreen.y * halfViewportHeight + halfViewportHeight - 8; // screen cull

				if ( validArea.containsPoint( screenPositionPixels ) ) {

					// save current RGB to temp texture
					renderer.copyFramebufferToTexture( screenPositionPixels, tempMap ); // render pink quad

					let uniforms = material1a.uniforms;
					uniforms[ 'scale' ].value = scale;
					uniforms[ 'screenPosition' ].value = positionScreen;
					renderer.renderBufferDirect( camera, null, geometry, material1a, mesh1, null ); // copy result to occlusionMap

					renderer.copyFramebufferToTexture( screenPositionPixels, occlusionMap ); // restore graphics

					uniforms = material1b.uniforms;
					uniforms[ 'scale' ].value = scale;
					uniforms[ 'screenPosition' ].value = positionScreen;
					renderer.renderBufferDirect( camera, null, geometry, material1b, mesh1, null ); // render elements

					const vecX = - positionScreen.x * 2;
					const vecY = - positionScreen.y * 2;

					for ( let i = 0, l = elements.length; i < l; i ++ ) {

						const element = elements[ i ];
						const uniforms = material2.uniforms;
						uniforms[ 'color' ].value.copy( element.color );
						uniforms[ 'map' ].value = element.texture;
						uniforms[ 'screenPosition' ].value.x = positionScreen.x + vecX * element.distance;
						uniforms[ 'screenPosition' ].value.y = positionScreen.y + vecY * element.distance;
						size = element.size / viewport.w;
						const invAspect = viewport.w / viewport.z;
						uniforms[ 'scale' ].value.set( size * invAspect, size );
						material2.uniformsNeedUpdate = true;
						renderer.renderBufferDirect( camera, null, geometry, material2, mesh2, null );

					}

				}

			};

			this.dispose = function () {

				material1a.dispose();
				material1b.dispose();
				material2.dispose();
				tempMap.dispose();
				occlusionMap.dispose();

				for ( let i = 0, l = elements.length; i < l; i ++ ) {

					elements[ i ].texture.dispose();

				}

			};

		}

	} //


	class LensflareElement {

		constructor( texture, size = 1, distance = 0, color = new THREE.Color( 0xffffff ) ) {

			this.texture = texture;
			this.size = size;
			this.distance = distance;
			this.color = color;

		}

	}

	LensflareElement.Shader = {
		uniforms: {
			'map': {
				value: null
			},
			'occlusionMap': {
				value: null
			},
			'color': {
				value: null
			},
			'scale': {
				value: null
			},
			'screenPosition': {
				value: null
			}
		},
		vertexShader:
  /* glsl */
  `

		precision highp float;

		uniform vec3 screenPosition;
		uniform vec2 scale;

		uniform sampler2D occlusionMap;

		attribute vec3 position;
		attribute vec2 uv;

		varying vec2 vUV;
		varying float vVisibility;

		void main() {

			vUV = uv;

			vec2 pos = position.xy;

			vec4 visibility = texture2D( occlusionMap, vec2( 0.1, 0.1 ) );
			visibility += texture2D( occlusionMap, vec2( 0.5, 0.1 ) );
			visibility += texture2D( occlusionMap, vec2( 0.9, 0.1 ) );
			visibility += texture2D( occlusionMap, vec2( 0.9, 0.5 ) );
			visibility += texture2D( occlusionMap, vec2( 0.9, 0.9 ) );
			visibility += texture2D( occlusionMap, vec2( 0.5, 0.9 ) );
			visibility += texture2D( occlusionMap, vec2( 0.1, 0.9 ) );
			visibility += texture2D( occlusionMap, vec2( 0.1, 0.5 ) );
			visibility += texture2D( occlusionMap, vec2( 0.5, 0.5 ) );

			vVisibility =        visibility.r / 9.0;
			vVisibility *= 1.0 - visibility.g / 9.0;
			vVisibility *=       visibility.b / 9.0;

			gl_Position = vec4( ( pos * scale + screenPosition.xy ).xy, screenPosition.z, 1.0 );

		}`,
		fragmentShader:
  /* glsl */
  `

		precision highp float;

		uniform sampler2D map;
		uniform vec3 color;

		varying vec2 vUV;
		varying float vVisibility;

		void main() {

			vec4 texture = texture2D( map, vUV );
			texture.a *= vVisibility;
			gl_FragColor = texture;
			gl_FragColor.rgb *= color;

		}`
	};

	Lensflare.Geometry = function () {

		const geometry = new THREE.BufferGeometry();
		const float32Array = new Float32Array( [ - 1, - 1, 0, 0, 0, 1, - 1, 0, 1, 0, 1, 1, 0, 1, 1, - 1, 1, 0, 0, 1 ] );
		const interleavedBuffer = new THREE.InterleavedBuffer( float32Array, 5 );
		geometry.setIndex( [ 0, 1, 2, 0, 2, 3 ] );
		geometry.setAttribute( 'position', new THREE.InterleavedBufferAttribute( interleavedBuffer, 3, 0, false ) );
		geometry.setAttribute( 'uv', new THREE.InterleavedBufferAttribute( interleavedBuffer, 2, 3, false ) );
		return geometry;

	}();

	THREE.Lensflare = Lensflare;
	THREE.LensflareElement = LensflareElement;

} )();