package.src.shaders.heatmap.fragment.glsl Maven / Gradle / Ivy

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A WebGL interactive maps library

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uniform highp float u_intensity;

varying vec2 v_extrude;

#pragma mapbox: define highp float weight

// Gaussian kernel coefficient: 1 / sqrt(2 * PI)
#define GAUSS_COEF 0.3989422804014327

void main() {
    #pragma mapbox: initialize highp float weight

    // Kernel density estimation with a Gaussian kernel of size 5x5
    float d = -0.5 * 3.0 * 3.0 * dot(v_extrude, v_extrude);
    float val = weight * u_intensity * GAUSS_COEF * exp(d);

    gl_FragColor = vec4(val, 1.0, 1.0, 1.0);

#ifdef OVERDRAW_INSPECTOR
    gl_FragColor = vec4(1.0);
#endif
}