// MinecraftPT — RTWSM Collapse Importance
// Collapses the 2D importance map into a 1D cumulative curve per row.

#include "/Lib/Settings.glsl"
#include "/Lib/Utilities.glsl"

const ivec3 workGroups = ivec3(RTW_RESOLUTION, 1, 1);
layout (local_size_x = 1) in;

layout (r32f) uniform writeonly image2D img_rtwImportance2D;
layout (rg16) uniform writeonly image2D img_rtwWarp1D;

uniform sampler2D rtwImportance2D;

void main(){
	int y = int(gl_GlobalInvocationID.y);

	// Sum importance across rows -> 1D profile
	float sum = 0.0;
	for (int x = 0; x < RTW_RESOLUTION; x++){
		sum += textureLod(rtwImportance2D, vec2(float(x) / float(RTW_RESOLUTION), float(y) / float(RTW_RESOLUTION_Y)), 0.0).r;
	}

	// Build cumulative distribution
	float cumulative = 0.0;
	for (int x = 0; x < RTW_RESOLUTION; x++){
		float imp = textureLod(rtwImportance2D, vec2(float(x) / float(RTW_RESOLUTION), float(y) / float(RTW_RESOLUTION_Y)), 0.0).r;
		cumulative += imp;
		float normalized = sum > 0.0 ? cumulative / sum : float(x) / float(RTW_RESOLUTION);

		imageStore(img_rtwWarp1D, ivec2(x, y), vec4(normalized, 1.0 - normalized, 0.0, 0.0));
	}
}