Doodle3D-Slicer/three.js-master/examples/js/shaders/EdgeShader.js
2015-06-12 15:58:26 +02:00

94 lines
3.1 KiB
JavaScript
Executable File

/**
* @author zz85 / https://github.com/zz85 | https://www.lab4games.net/zz85/blog
*
* Edge Detection Shader using Frei-Chen filter
* Based on http://rastergrid.com/blog/2011/01/frei-chen-edge-detector
*
* aspect: vec2 of (1/width, 1/height)
*/
THREE.EdgeShader = {
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[9];",
// hard coded matrix values!!!! as suggested in https://github.com/neilmendoza/ofxPostProcessing/blob/master/src/EdgePass.cpp#L45
"const mat3 g0 = mat3( 0.3535533845424652, 0, -0.3535533845424652, 0.5, 0, -0.5, 0.3535533845424652, 0, -0.3535533845424652 );",
"const mat3 g1 = mat3( 0.3535533845424652, 0.5, 0.3535533845424652, 0, 0, 0, -0.3535533845424652, -0.5, -0.3535533845424652 );",
"const mat3 g2 = mat3( 0, 0.3535533845424652, -0.5, -0.3535533845424652, 0, 0.3535533845424652, 0.5, -0.3535533845424652, 0 );",
"const mat3 g3 = mat3( 0.5, -0.3535533845424652, 0, -0.3535533845424652, 0, 0.3535533845424652, 0, 0.3535533845424652, -0.5 );",
"const mat3 g4 = mat3( 0, -0.5, 0, 0.5, 0, 0.5, 0, -0.5, 0 );",
"const mat3 g5 = mat3( -0.5, 0, 0.5, 0, 0, 0, 0.5, 0, -0.5 );",
"const mat3 g6 = mat3( 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.6666666865348816, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204 );",
"const mat3 g7 = mat3( -0.3333333432674408, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, 0.6666666865348816, 0.1666666716337204, -0.3333333432674408, 0.1666666716337204, -0.3333333432674408 );",
"const mat3 g8 = mat3( 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408, 0.3333333432674408 );",
"void main(void)",
"{",
"G[0] = g0,",
"G[1] = g1,",
"G[2] = g2,",
"G[3] = g3,",
"G[4] = g4,",
"G[5] = g5,",
"G[6] = g6,",
"G[7] = g7,",
"G[8] = g8;",
"mat3 I;",
"float cnv[9];",
"vec3 sample;",
/* 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<9; 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;",
"}",
"float M = (cnv[0] + cnv[1]) + (cnv[2] + cnv[3]);",
"float S = (cnv[4] + cnv[5]) + (cnv[6] + cnv[7]) + (cnv[8] + M);",
"gl_FragColor = vec4(vec3(sqrt(M/S)), 1.0);",
"}",
].join("\n")
};