#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"
// MinecraftPT — Diffuse Variance Estimation
// Computes luminance moments to drive temporal accumulation and firefly rejection.

#ifndef DIFFUSE_VARIANCE_ESTIMATION_GLSL
#define DIFFUSE_VARIANCE_ESTIMATION_GLSL

#include "/Lib/Utilities.glsl"

vec2 DiffuseEstimateVariance(vec3 color, vec2 texelCoord){
	float lum = luminance(color);
	float lum2 = lum * lum;

	// Local variance from neighbors (5-tap)
	float variance = 0.0;
	for (int i = -1; i <= 1; i++){
	for (int j = -1; j <= 1; j++){
		if (i == 0 && j == 0) continue;
		vec3 c = texelFetch(colortex7, ivec2(texelCoord) + ivec2(i, j), 0).rgb;
		float l = luminance(c);
		variance += (l - lum) * (l - lum);
	}}
	variance /= 8.0;

	// Clamp fireflies
	float firefly = step(1.0, lum / max(variance * 4.0, 0.001));

	return vec2(lum, firefly);
}

#endif