<!
//  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;
layout(location = 1) out vec4 _fragColor1;
layout(location = 2) out vec4 _fragColor2;

uniform sampler2D normalFittingMap;

vec3 bestFitNormal(vec3 normal) {
    vec3 absNorm = abs(normal);
    float maxNAbs = max(absNorm.z, max(absNorm.x, absNorm.y));

    vec2 texcoord = (absNorm.z < maxNAbs ? 
                        (absNorm.y < maxNAbs ? absNorm.yz : absNorm.xz) :
                        absNorm.xy);
    texcoord = (texcoord.x < texcoord.y ? texcoord.yx : texcoord.xy);
    texcoord.y /= texcoord.x;
    vec3 cN = normal / maxNAbs;

    float fittingScale = texture(normalFittingMap, texcoord).a;
    cN *= fittingScale;
    return (cN * 0.5 + 0.5);
}


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

const float DEFAULT_ROUGHNESS = 0.9;
const float DEFAULT_SHININESS = 10;
const float DEFAULT_METALLIC = 0;
const vec3 DEFAULT_SPECULAR = vec3(0.1);
const vec3 DEFAULT_EMISSIVE = vec3(0.0);
const float DEFAULT_OCCLUSION = 1.0;
const vec3 DEFAULT_FRESNEL = DEFAULT_EMISSIVE;

void packDeferredFragment(vec3 normal, float alpha, vec3 albedo, float roughness, float metallic, vec3 emissive, float occlusion) {
    if (alpha != 1.0) {
        discard;
    }
    _fragColor0 = vec4(albedo, packShadedMetallic(metallic));
    _fragColor1 = vec4(bestFitNormal(normal), clamp(roughness, 0.0, 1.0));
    _fragColor2 = vec4(emissive, occlusion);
}


void packDeferredFragmentLightmap(vec3 normal, float alpha, vec3 albedo, float roughness, float metallic, vec3 fresnel, vec3 emissive) {
    if (alpha != 1.0) {
        discard;
    }
    _fragColor0 = vec4(albedo, packLightmappedMetallic(metallic));
    _fragColor1 = vec4(bestFitNormal(normal), clamp(roughness, 0.0, 1.0));
    _fragColor2 = vec4(emissive, 1.0);
}

void packDeferredFragmentUnlit(vec3 normal, float alpha, vec3 color) {
    if (alpha != 1.0) {
        discard;
    }
    _fragColor0 = vec4(color, packUnlit());
    _fragColor1 = vec4(bestFitNormal(normal), 1.0);
    //_fragColor2 = vec4(vec3(0.0), 1.0); // If unlit, do not worry about the emissive color target
}

void packDeferredFragmentTranslucent(vec3 normal, float alpha, vec3 albedo, vec3 fresnel, float roughness) {
    if (alpha <= 0.0) {
        discard;
    }
    _fragColor0 = vec4(albedo.rgb, alpha);
}

<@endif@>