three.js/examples/js/shaders/NormalMapShader.js

( function () {

	/**
 * Normal map shader
 * - compute normals from heightmap
 */

	var NormalMapShader = {
		uniforms: {
			'heightMap': {
				value: null
			},
			'resolution': {
				value: new THREE.Vector2( 512, 512 )
			},
			'scale': {
				value: new THREE.Vector2( 1, 1 )
			},
			'height': {
				value: 0.05
			}
		},
		vertexShader: [ 'varying vec2 vUv;', 'void main() {', '	vUv = uv;', '	gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );', '}' ].join( '\n' ),
		fragmentShader: [ 'uniform float height;', 'uniform vec2 resolution;', 'uniform sampler2D heightMap;', 'varying vec2 vUv;', 'void main() {', '	float val = texture2D( heightMap, vUv ).x;', '	float valU = texture2D( heightMap, vUv + vec2( 1.0 / resolution.x, 0.0 ) ).x;', '	float valV = texture2D( heightMap, vUv + vec2( 0.0, 1.0 / resolution.y ) ).x;', '	gl_FragColor = vec4( ( 0.5 * normalize( vec3( val - valU, val - valV, height	) ) + 0.5 ), 1.0 );', '}' ].join( '\n' )
	};

	THREE.NormalMapShader = NormalMapShader;

} )();