#version 430

#include "common/compute.h"

BEGIN_DRAW_TEXTURES
	TEXTURE_2D(0, inTex)
END_DRAW_TEXTURES

BEGIN_DRAW_UNIFORMS
	UNIFORM(vec4, screenSize)
	// Premultiplied exposure, already contains 2^exposure.
	UNIFORM(float, exposure)
END_DRAW_UNIFORMS

STORAGE_2D(0, rgba8, outTex);

vec3 applyTonemapper(vec3 color)
{
	float whitePoint = 10.0;
	// Extendend Reinhard:
	// https://www-old.cs.utah.edu/docs/techreports/2002/pdf/UUCS-02-001.pdf
	return color * (vec3(1.0) + color / (whitePoint * whitePoint)) / (vec3(1.0) + color);
}

layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
void main()
{
	ivec2 position = ivec2(gl_GlobalInvocationID.xy);
	if (any(greaterThanEqual(position, ivec2(screenSize.xy))))
		return;
	vec3 hdrColor = texelFetch(GET_DRAW_TEXTURE_2D(inTex), position, 0).rgb;
	vec3 sdrColor = applyTonemapper(hdrColor * exposure);
	imageStore(outTex, position, vec4(sdrColor, 1.0));
}