phaser/src/renderer/webgl/shaders/FXShadow-frag.js

module.exports = [
    '#define SHADER_NAME SHADOW_FS',
    'precision mediump float;',
    'uniform sampler2D uMainSampler;',
    'varying vec2 outTexCoord;',
    'uniform vec2 lightPosition;',
    'uniform vec4 color;',
    'uniform float decay;',
    'uniform float power;',
    'uniform float intensity;',
    'uniform int samples;',
    'const int MAX = 12;',
    'void main ()',
    '{',
    '    vec4 texture = texture2D(uMainSampler, outTexCoord);',
    '    vec2 pc = (lightPosition - outTexCoord) * intensity;',
    '    float shadow = 0.0;',
    '    float limit = max(float(MAX), float(samples));',
    '    for (int i = 0; i < MAX; ++i)',
    '    {',
    '        if (i >= samples)',
    '        {',
    '            break;',
    '        }',
    '        shadow += texture2D(uMainSampler, outTexCoord + float(i) * decay / limit * pc).a * power;',
    '    }',
    '    float mask = 1.0 - texture.a;',
    '    gl_FragColor = mix(texture, color, shadow * mask);',
    '}',
].join('\n');