<!
//  MaterialTextures.slh
//  fragment shader
//
//  Created by Sam Gateau on 2/22/16
//  Copyright 2016 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 MODEL_MATERIAL_TEXTURES_SLH@>
<@def MODEL_MATERIAL_TEXTURES_SLH@>


<@func declareMaterialTexMapArrayBuffer()@>

const int MAX_TEXCOORDS = 2;

struct TexMapArray { 
    mat4 _texcoordTransforms[MAX_TEXCOORDS];
    vec4 _lightmapParams;
};

uniform texMapArrayBuffer {
    TexMapArray _texMapArray;
};

TexMapArray getTexMapArray() {
    return _texMapArray;
}

<@func evalTexMapArrayTexcoord0(texMapArray, inTexcoord0, outTexcoord0)@>
{
    <$outTexcoord0$> = (<$texMapArray$>._texcoordTransforms[0] * vec4(<$inTexcoord0$>.st, 0.0, 1.0)).st;
}
<@endfunc@>

<@func evalTexMapArrayTexcoord1(texMapArray, inTexcoord1, outTexcoord1)@>
{
    <$outTexcoord1$> = (<$texMapArray$>._texcoordTransforms[1] * vec4(<$inTexcoord1$>.st, 0.0, 1.0)).st;
}
<@endfunc@>

<@endfunc@>


<@func declareMaterialTextures(withAlbedo, withRoughness, withNormal, withMetallic, withEmissive, withOcclusion, withScattering)@>

<@if withAlbedo@>
uniform sampler2D albedoMap;
vec4 fetchAlbedoMap(vec2 uv) {
    return texture(albedoMap, uv);
}
<@endif@>

<@if withRoughness@>
uniform sampler2D roughnessMap;
float fetchRoughnessMap(vec2 uv) {
    return (texture(roughnessMap, uv).r);
}
<@endif@>

<@if withNormal@>
uniform sampler2D normalMap;
vec3 fetchNormalMap(vec2 uv) {
    // unpack normal, swizzle to get into hifi tangent space with Y axis pointing out
    vec2 t = 2.0 * (texture(normalMap, uv).rg - vec2(0.5, 0.5));
    vec2 t2 = t*t;
    return vec3(t.x, sqrt(1 - t2.x - t2.y), t.y);
}
<@endif@>

<@if withMetallic@>
uniform sampler2D metallicMap;
float fetchMetallicMap(vec2 uv) {
    return (texture(metallicMap, uv).r);
}
<@endif@>

<@if withEmissive@>
uniform sampler2D emissiveMap;
vec3 fetchEmissiveMap(vec2 uv) {
    return texture(emissiveMap, uv).rgb;
}
<@endif@>

<@if withOcclusion@>
uniform sampler2D occlusionMap;
float fetchOcclusionMap(vec2 uv) {
    return texture(occlusionMap, uv).r;
}
<@endif@>

<@if withScattering@>
uniform sampler2D scatteringMap;
float fetchScatteringMap(vec2 uv) {
    float scattering = texture(scatteringMap, uv).r; // boolean scattering for now
    return max(((scattering - 0.1) / 0.9), 0.0);
    return texture(scatteringMap, uv).r; // boolean scattering for now
}
<@endif@>

<@endfunc@>


<@func fetchMaterialTexturesCoord0(matKey, texcoord0, albedo, roughness, normal, metallic, emissive, scattering)@>
<@if albedo@>
    vec4 <$albedo$> = (((<$matKey$> & (ALBEDO_MAP_BIT | OPACITY_MASK_MAP_BIT | OPACITY_TRANSLUCENT_MAP_BIT)) != 0) ? fetchAlbedoMap(<$texcoord0$>) : vec4(1.0));
<@endif@>
<@if roughness@>
    float <$roughness$> = (((<$matKey$> & ROUGHNESS_MAP_BIT) != 0) ? fetchRoughnessMap(<$texcoord0$>) : 1.0);
<@endif@>
<@if normal@>
    vec3 <$normal$> = (((<$matKey$> & NORMAL_MAP_BIT) != 0) ? fetchNormalMap(<$texcoord0$>) : vec3(0.0, 1.0, 0.0));
<@endif@>
<@if metallic@>
    float <$metallic$> = (((<$matKey$> & METALLIC_MAP_BIT) != 0) ? fetchMetallicMap(<$texcoord0$>) : 0.0);
<@endif@>
<@if emissive@>
    vec3 <$emissive$> = (((<$matKey$> & EMISSIVE_MAP_BIT) != 0) ? fetchEmissiveMap(<$texcoord0$>) : vec3(0.0));
<@endif@>
<@if scattering@>
    float <$scattering$> = (((<$matKey$> & SCATTERING_MAP_BIT) != 0) ? fetchScatteringMap(<$texcoord0$>) : 0.0);
<@endif@>
<@endfunc@>

<@func fetchMaterialTexturesCoord1(matKey, texcoord1, occlusion, lightmapVal)@>
<@if occlusion@>
    float <$occlusion$> = (((<$matKey$> & OCCLUSION_MAP_BIT) != 0) ? fetchOcclusionMap(<$texcoord1$>) : 1.0);
<@endif@>
<@if lightmapVal@>
    vec3 <$lightmapVal$> = fetchLightmapMap(<$texcoord1$>);
<@endif@>
<@endfunc@>


<@func declareMaterialLightmap()@>

<$declareMaterialTexMapArrayBuffer()$>

uniform sampler2D emissiveMap;
vec3 fetchLightmapMap(vec2 uv) {
    vec2 emissiveParams = getTexMapArray()._lightmapParams.xy;
    return (vec3(emissiveParams.x) + emissiveParams.y * texture(emissiveMap, uv).rgb);
}
<@endfunc@>

<@func tangentToViewSpace(fetchedNormal, interpolatedNormal, interpolatedTangent, normal)@>
{
    vec3 normalizedNormal = normalize(<$interpolatedNormal$>.xyz);
    vec3 normalizedTangent = normalize(<$interpolatedTangent$>.xyz);
    vec3 normalizedBitangent = normalize(cross(normalizedNormal, normalizedTangent));
    vec3 localNormal = <$fetchedNormal$>;
    <$normal$> = vec3(normalizedTangent * localNormal.x + normalizedBitangent * localNormal.y + normalizedNormal * localNormal.z);
}
<@endfunc@>

<@func tangentToViewSpaceLOD(fragPos, fetchedNormal, interpolatedNormal, interpolatedTangent, normal)@>
{
    vec3 normalizedNormal = normalize(<$interpolatedNormal$>.xyz);
    vec3 normalizedTangent = normalize(<$interpolatedTangent$>.xyz);
    vec3 normalizedBitangent = normalize(cross(normalizedNormal, normalizedTangent));
    // attenuate the normal map divergence from the mesh normal based on distance
    // THe attenuation range [20,100] meters from the eye is arbitrary for now
    vec3 localNormal = mix(<$fetchedNormal$>, vec3(0.0, 1.0, 0.0), smoothstep(20, 100, (-<$fragPos$>).z));
    <$normal$> = vec3(normalizedTangent * localNormal.x + normalizedNormal * localNormal.y + normalizedBitangent * localNormal.z);
}
<@endfunc@>

<@func evalMaterialAlbedo(fetchedAlbedo, materialAlbedo, matKey, albedo)@>
{
    <$albedo$>.xyz = (((<$matKey$> & ALBEDO_VAL_BIT) != 0) ? <$materialAlbedo$> : vec3(1.0));

    if (((<$matKey$> & ALBEDO_MAP_BIT) != 0)) {
        <$albedo$>.xyz *= <$fetchedAlbedo$>.xyz;
    }
}
<@endfunc@>

<@func evalMaterialOpacity(fetchedOpacity, materialOpacity, matKey, opacity)@>
{
    const float OPACITY_MASK_THRESHOLD = 0.5;
    <$opacity$> = (((<$matKey$> & (OPACITY_TRANSLUCENT_MAP_BIT | OPACITY_MASK_MAP_BIT)) != 0) ?
                     (((<$matKey$> & OPACITY_MASK_MAP_BIT) != 0) ? step(OPACITY_MASK_THRESHOLD, <$fetchedOpacity$>) : <$fetchedOpacity$>) :
                     1.0) * <$materialOpacity$>;
}
<@endfunc@>

<@func discardTransparent(opacity)@>
{
    if (<$opacity$> < 1.0) {
        discard;
    }
}
<@endfunc@>

<@func evalMaterialRoughness(fetchedRoughness, materialRoughness, matKey, roughness)@>
{
    <$roughness$> = (((<$matKey$> & ROUGHNESS_MAP_BIT) != 0) ? <$fetchedRoughness$> : <$materialRoughness$>);
}
<@endfunc@>

<@func evalMaterialMetallic(fetchedMetallic, materialMetallic, matKey, metallic)@>
{
    <$metallic$> = (((<$matKey$> & METALLIC_MAP_BIT) != 0) ? <$fetchedMetallic$> : <$materialMetallic$>);
}
<@endfunc@>

<@func evalMaterialEmissive(fetchedEmissive, materialEmissive, matKey, emissive)@>
{
    <$emissive$> = (((<$matKey$> & EMISSIVE_MAP_BIT) != 0) ? <$fetchedEmissive$> : <$materialEmissive$>);
}
<@endfunc@>

<@func evalMaterialOcclusion(fetchedOcclusion, matKey, occlusion)@>
{
    <$occlusion$> = <$fetchedOcclusion$>;
}
<@endfunc@>

<@func evalMaterialScattering(fetchedScattering, materialScattering, matKey, scattering)@>
{
    <$scattering$> = (((<$matKey$> & SCATTERING_MAP_BIT) != 0) ? <$fetchedScattering$> : <$materialScattering$>);
}
<@endfunc@>

<@endif@>