three-shaders/shaders/NormalMapShader.js

three-shaders - a library of shaders included with Three.js library

/**
 * @author alteredq / http://alteredqualia.com/
 *
 * Normal map shader
 * - compute normals from heightmap
 */

var THREE = require('three');

function NormalMapShader() {

	return {

	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 );

		}

	`,

	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 );

		}

	`
	}

};

module.exports = NormalMapShader;