<!
//  DeferredBufferWrite.slh
//  libraries/render-utils/src
//
//  Created by Sam Gateau on 1/12/15.
//  Copyright 2013 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
!>
<@if not DEFERRED_BUFFER_WRITE_SLH@>
<@def DEFERRED_BUFFER_WRITE_SLH@>

<@include DeferredBuffer.slh@>


layout(location=0) out vec4 _fragColor0; // albedo / metallic
layout(location=1) out vec4 _fragColor1; // Normal
layout(location=2) out vec4 _fragColor2; // scattering / emissive / occlusion
layout(location=3) out vec4 _fragColor3; // emissive

// the alpha threshold
const float alphaThreshold = 0.5;
float evalOpaqueFinalAlpha(float alpha, float mapAlpha) {
    return mix(alpha, 1.0 - alpha, step(mapAlpha, alphaThreshold));
}

<@include DefaultMaterials.slh@>
<@include LightingModel.slh@>

void packDeferredFragment(vec3 normal, float alpha, vec3 albedo, float roughness, float metallic, vec3 emissive, float occlusion, float scattering) {
    if (alpha < 1.0) {
        discard;
    }

    float check = float(scattering > 0.0);
    _fragColor0 = vec4(albedo, mix(packShadedMetallic(metallic), packScatteringMetallic(metallic), check));
    _fragColor1 = vec4(packNormal(normal), clamp(roughness, 0.0, 1.0));
    _fragColor2 = vec4(mix(emissive, vec3(scattering), check), occlusion);
    _fragColor3 = vec4(isEmissiveEnabled() * emissive, 1.0);
}

void packDeferredFragmentLightmap(vec3 normal, float alpha, vec3 albedo, float roughness, float metallic, vec3 lightmap) {
    if (alpha < 1.0) {
        discard;
    }

    _fragColor0 = vec4(albedo, packLightmappedMetallic(metallic));
    _fragColor1 = vec4(packNormal(normal), clamp(roughness, 0.0, 1.0));
    _fragColor2 = vec4(isLightmapEnabled() * lightmap, 1.0);
    _fragColor3 = vec4(isLightmapEnabled() * lightmap * albedo, 1.0);
}

void packDeferredFragmentUnlit(vec3 normal, float alpha, vec3 color) {
    // to reduce texel flickering for floating point error we discard when alpha is "almost one"
    if (alpha < 0.999999) {
        discard;
    }
    _fragColor0 = vec4(color, packUnlit());
    _fragColor1 = vec4(packNormal(normal), 1.0);
    _fragColor2 = vec4(vec3(0.0), 1.0);
    _fragColor3 = vec4(color, 1.0);
}

void packDeferredFragmentTranslucent(vec3 normal, float alpha, vec3 albedo, float roughness) {
    if (alpha <= 0.0) {
        discard;
    }
    _fragColor0 = vec4(albedo.rgb, alpha);
    _fragColor1 = vec4(packNormal(normal), clamp(roughness, 0.0, 1.0));
    _fragColor2 = vec4(vec3(0.0), 1.0);
    _fragColor3 = vec4(0.0);
}

<@endif@>