#version 450 core

layout( location = 0 ) uniform sampler2D u_InputTexture;
layout( location = 1 ) uniform int u_LOD;
layout( location = 2 ) uniform vec2 u_OutputSize;

layout( location = 0 ) out vec4 o_Color;

void main( void )
{
	vec2 ts = textureSize( u_InputTexture , u_LOD );
	ivec2 pos = ivec2( ts * gl_FragCoord.xy / u_OutputSize );
	vec3 c = vec3( texelFetch( u_InputTexture , pos , u_LOD ).r );
	o_Color = vec4( 1 - c / ( c + 1 ) , 1 );
}