cesium/Source/Shaders/PostProcessFilters/GaussianBlur1D.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 "#define SAMPLES 8\n\
\n\
uniform float delta;\n\
uniform float sigma;\n\
uniform float direction; // 0.0 for x direction, 1.0 for y direction\n\
\n\
uniform sampler2D u_texture;\n\
uniform vec2 u_step;\n\
\n\
varying vec2 v_textureCoordinates;\n\
\n\
//  Incremental Computation of the Gaussian:\n\
//  http://http.developer.nvidia.com/GPUGems3/gpugems3_ch40.html\n\
\n\
void main()\n\
{\n\
    vec2 st = v_textureCoordinates;\n\
    \n\
    vec2 dir = vec2(1.0 - direction, direction);\n\
    \n\
    vec3 g;\n\
    g.x = 1.0 / (sqrt(czm_twoPi) * sigma);\n\
    g.y = exp((-0.5 * delta * delta) / (sigma * sigma));\n\
    g.z = g.y * g.y;\n\
    \n\
    vec4 result = texture2D(u_texture, st) * g.x;\n\
    for (int i = 1; i < SAMPLES; ++i)\n\
    {\n\
        g.xy *= g.yz;\n\
        \n\
        vec2 offset = float(i) * dir * u_step;\n\
        result += texture2D(u_texture, st - offset) * g.x;\n\
        result += texture2D(u_texture, st + offset) * g.x;\n\
    }\n\
    \n\
    gl_FragColor = result;\n\
}\n\
";
});