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/**
* Simple downsample shader. Takes the average of the 4 texels of lower mip.
**/
uniform sampler2DArray source;
uniform float fireflyFactor;
in vec2 uvs;
flat in float layer;
out vec4 FragColor;
float brightness(vec3 c)
{
return max(max(c.r, c.g), c.b);
}
void main()
{
#if 0
/* Reconstructing Target uvs like this avoid missing pixels if NPO2 */
vec2 uvs = gl_FragCoord.xy * 2.0 / vec2(textureSize(source, 0));
FragColor = textureLod(source, vec3(uvs, layer), 0.0);
#else
vec2 texel_size = 1.0 / vec2(textureSize(source, 0));
vec2 uvs = gl_FragCoord.xy * 2.0 * texel_size;
vec4 ofs = texel_size.xyxy * vec4(0.75, 0.75, -0.75, -0.75);
FragColor = textureLod(source, vec3(uvs + ofs.xy, layer), 0.0);
FragColor += textureLod(source, vec3(uvs + ofs.xw, layer), 0.0);
FragColor += textureLod(source, vec3(uvs + ofs.zy, layer), 0.0);
FragColor += textureLod(source, vec3(uvs + ofs.zw, layer), 0.0);
FragColor *= 0.25;
/* Clamped brightness. */
float luma = max(1e-8, brightness(FragColor.rgb));
FragColor *= 1.0 - max(0.0, luma - fireflyFactor) / luma;
#endif
}
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