three.js/examples/js/shaders/FresnelShader.js

( function () {

	/**
 * Based on Nvidia Cg tutorial
 */
	var FresnelShader = {
		uniforms: {
			'mRefractionRatio': {
				value: 1.02
			},
			'mFresnelBias': {
				value: 0.1
			},
			'mFresnelPower': {
				value: 2.0
			},
			'mFresnelScale': {
				value: 1.0
			},
			'tCube': {
				value: null
			}
		},
		vertexShader: [ 'uniform float mRefractionRatio;', 'uniform float mFresnelBias;', 'uniform float mFresnelScale;', 'uniform float mFresnelPower;', 'varying vec3 vReflect;', 'varying vec3 vRefract[3];', 'varying float vReflectionFactor;', 'void main() {', '	vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );', '	vec4 worldPosition = modelMatrix * vec4( position, 1.0 );', '	vec3 worldNormal = normalize( mat3( modelMatrix[0].xyz, modelMatrix[1].xyz, modelMatrix[2].xyz ) * normal );', '	vec3 I = worldPosition.xyz - cameraPosition;', '	vReflect = reflect( I, worldNormal );', '	vRefract[0] = refract( normalize( I ), worldNormal, mRefractionRatio );', '	vRefract[1] = refract( normalize( I ), worldNormal, mRefractionRatio * 0.99 );', '	vRefract[2] = refract( normalize( I ), worldNormal, mRefractionRatio * 0.98 );', '	vReflectionFactor = mFresnelBias + mFresnelScale * pow( 1.0 + dot( normalize( I ), worldNormal ), mFresnelPower );', '	gl_Position = projectionMatrix * mvPosition;', '}' ].join( '\n' ),
		fragmentShader: [ 'uniform samplerCube tCube;', 'varying vec3 vReflect;', 'varying vec3 vRefract[3];', 'varying float vReflectionFactor;', 'void main() {', '	vec4 reflectedColor = textureCube( tCube, vec3( -vReflect.x, vReflect.yz ) );', '	vec4 refractedColor = vec4( 1.0 );', '	refractedColor.r = textureCube( tCube, vec3( -vRefract[0].x, vRefract[0].yz ) ).r;', '	refractedColor.g = textureCube( tCube, vec3( -vRefract[1].x, vRefract[1].yz ) ).g;', '	refractedColor.b = textureCube( tCube, vec3( -vRefract[2].x, vRefract[2].yz ) ).b;', '	gl_FragColor = mix( refractedColor, reflectedColor, clamp( vReflectionFactor, 0.0, 1.0 ) );', '}' ].join( '\n' )
	};

	THREE.FresnelShader = FresnelShader;

} )();