three.js/examples/js/shaders/BleachBypassShader.js

console.warn( "THREE.BleachBypassShader: As part of the transition to ES6 Modules, the files in 'examples/js' were deprecated in May 2020 (r117) and will be deleted in December 2020 (r124). You can find more information about developing using ES6 Modules in https://threejs.org/docs/#manual/en/introduction/Installation." );
/**
 * Bleach bypass shader [http://en.wikipedia.org/wiki/Bleach_bypass]
 * - based on Nvidia example
 * http://developer.download.nvidia.com/shaderlibrary/webpages/shader_library.html#post_bleach_bypass
 */

THREE.BleachBypassShader = {

	uniforms: {

		"tDiffuse": { value: null },
		"opacity": { value: 1.0 }

	},

	vertexShader: [

		"varying vec2 vUv;",

		"void main() {",

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

		"}"

	].join( "\n" ),

	fragmentShader: [

		"uniform float opacity;",

		"uniform sampler2D tDiffuse;",

		"varying vec2 vUv;",

		"void main() {",

		"	vec4 base = texture2D( tDiffuse, vUv );",

		"	vec3 lumCoeff = vec3( 0.25, 0.65, 0.1 );",
		"	float lum = dot( lumCoeff, base.rgb );",
		"	vec3 blend = vec3( lum );",

		"	float L = min( 1.0, max( 0.0, 10.0 * ( lum - 0.45 ) ) );",

		"	vec3 result1 = 2.0 * base.rgb * blend;",
		"	vec3 result2 = 1.0 - 2.0 * ( 1.0 - blend ) * ( 1.0 - base.rgb );",

		"	vec3 newColor = mix( result1, result2, L );",

		"	float A2 = opacity * base.a;",
		"	vec3 mixRGB = A2 * newColor.rgb;",
		"	mixRGB += ( ( 1.0 - A2 ) * base.rgb );",

		"	gl_FragColor = vec4( mixRGB, base.a );",

		"}"

	].join( "\n" )

};