Doodle3D-Slicer/three.js-master/examples/js/shaders/EdgeShader2.js

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2015-06-12 15:58:26 +02:00
/**
* @author zz85 / https://github.com/zz85 | https://www.lab4games.net/zz85/blog
*
* Edge Detection Shader using Sobel filter
* Based on http://rastergrid.com/blog/2011/01/frei-chen-edge-detector
*
* aspect: vec2 of (1/width, 1/height)
*/
THREE.EdgeShader2 = {
uniforms: {
"tDiffuse": { type: "t", value: null },
"aspect": { type: "v2", value: new THREE.Vector2( 512, 512 ) },
},
vertexShader: [
"varying vec2 vUv;",
"void main() {",
"vUv = uv;",
"gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );",
"}"
].join("\n"),
fragmentShader: [
"uniform sampler2D tDiffuse;",
"varying vec2 vUv;",
"uniform vec2 aspect;",
"vec2 texel = vec2(1.0 / aspect.x, 1.0 / aspect.y);",
"mat3 G[2];",
"const mat3 g0 = mat3( 1.0, 2.0, 1.0, 0.0, 0.0, 0.0, -1.0, -2.0, -1.0 );",
"const mat3 g1 = mat3( 1.0, 0.0, -1.0, 2.0, 0.0, -2.0, 1.0, 0.0, -1.0 );",
"void main(void)",
"{",
"mat3 I;",
"float cnv[2];",
"vec3 sample;",
"G[0] = g0;",
"G[1] = g1;",
/* fetch the 3x3 neighbourhood and use the RGB vector's length as intensity value */
"for (float i=0.0; i<3.0; i++)",
"for (float j=0.0; j<3.0; j++) {",
"sample = texture2D( tDiffuse, vUv + texel * vec2(i-1.0,j-1.0) ).rgb;",
"I[int(i)][int(j)] = length(sample);",
"}",
/* calculate the convolution values for all the masks */
"for (int i=0; i<2; i++) {",
"float dp3 = dot(G[i][0], I[0]) + dot(G[i][1], I[1]) + dot(G[i][2], I[2]);",
"cnv[i] = dp3 * dp3; ",
"}",
"gl_FragColor = vec4(0.5 * sqrt(cnv[0]*cnv[0]+cnv[1]*cnv[1]));",
"} ",
].join("\n")
};