//This file is automatically rebuilt by the Cesium build process.
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export default "uniform sampler2D colorTexture;\n\
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\n\
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uniform float avgLuminance;\n\
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uniform float threshold;\n\
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uniform float offset;\n\
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\n\
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varying vec2 v_textureCoordinates;\n\
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\n\
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float key(float avg)\n\
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{\n\
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float guess = 1.5 - (1.5 / (avg * 0.1 + 1.0));\n\
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return max(0.0, guess) + 0.1;\n\
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}\n\
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\n\
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// See section 9. \"The bright-pass filter\" of Realtime HDR Rendering\n\
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// http://www.cg.tuwien.ac.at/research/publications/2007/Luksch_2007_RHR/Luksch_2007_RHR-RealtimeHDR%20.pdf\n\
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\n\
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void main()\n\
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{\n\
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vec4 color = texture2D(colorTexture, v_textureCoordinates);\n\
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vec3 xyz = czm_RGBToXYZ(color.rgb);\n\
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float luminance = xyz.r;\n\
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\n\
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float scaledLum = key(avgLuminance) * luminance / avgLuminance;\n\
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float brightLum = max(scaledLum - threshold, 0.0);\n\
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float brightness = brightLum / (offset + brightLum);\n\
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\n\
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xyz.r = brightness;\n\
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gl_FragColor = vec4(czm_XYZToRGB(xyz), 1.0);\n\
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}\n\
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";
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