cesium/Source/Shaders/PostProcessStages/EdgeDetection.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

//This file is automatically rebuilt by the Cesium build process.
define(function() {
    'use strict';
    return "uniform sampler2D depthTexture;\n\
uniform float length;\n\
uniform vec4 color;\n\
\n\
varying vec2 v_textureCoordinates;\n\
\n\
void main(void)\n\
{\n\
    float directions[3];\n\
    directions[0] = -1.0;\n\
    directions[1] = 0.0;\n\
    directions[2] = 1.0;\n\
\n\
    float scalars[3];\n\
    scalars[0] = 3.0;\n\
    scalars[1] = 10.0;\n\
    scalars[2] = 3.0;\n\
\n\
    float padx = 1.0 / czm_viewport.z;\n\
    float pady = 1.0 / czm_viewport.w;\n\
\n\
    float horizEdge = 0.0;\n\
    float vertEdge = 0.0;\n\
\n\
    for (int i = 0; i < 3; ++i) {\n\
        float dir = directions[i];\n\
        float scale = scalars[i];\n\
\n\
        horizEdge -= texture2D(depthTexture, v_textureCoordinates + vec2(-padx, dir * pady)).x * scale;\n\
        horizEdge += texture2D(depthTexture, v_textureCoordinates + vec2(padx, dir * pady)).x * scale;\n\
\n\
        vertEdge -= texture2D(depthTexture, v_textureCoordinates + vec2(dir * padx, -pady)).x * scale;\n\
        vertEdge += texture2D(depthTexture, v_textureCoordinates + vec2(dir * padx, pady)).x * scale;\n\
    }\n\
\n\
    float len = sqrt(horizEdge * horizEdge + vertEdge * vertEdge);\n\
    float alpha = len > length ? 1.0 : 0.0;\n\
    gl_FragColor = vec4(color.rgb, alpha);\n\
}\n\
";
});