<@include gpu/Config.slh@>
<$VERSION_HEADER$>
//  BloomThreshold.frag
//  Perform a soft threshold on an input texture and downsample to half size in one go.
//
//  Created by Olivier Prat on 09/26/2017
//  Copyright 2017 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
<@include BloomThreshold.shared.slh@>
<@include render-utils/ShaderConstants.h@>

LAYOUT(binding=RENDER_UTILS_TEXTURE_BLOOM_COLOR) uniform sampler2D colorMap;
LAYOUT_STD140(binding=RENDER_UTILS_BUFFER_BLOOM_PARAMS) uniform parametersBuffer {
    Parameters parameters;
};

layout(location=0) in vec2 varTexCoord0;
layout(location=0) out vec4 outFragColor;

void main(void) {
    vec2 startUv = varTexCoord0;
    vec4 maskedColor = vec4(0,0,0,0);

    for (int y=0 ; y<parameters._sampleCount ; y++) {
        vec2 uv = startUv;

        for (int x=0 ; x<parameters._sampleCount ; x++) {
            vec4 color = texture(colorMap, uv);
            float luminance = (color.r+color.g+color.b) / 3.0;
            float mask = clamp((luminance-parameters._threshold)*0.25, 0.0, 1.0);

            color *= mask;
            maskedColor += color;
            uv.x += parameters._deltaUV.x;
        }

        startUv.y += parameters._deltaUV.y;
    }
    maskedColor /= float(parameters._sampleCount * parameters._sampleCount);
    outFragColor = vec4(maskedColor.rgb, 1.0);
}