<!
//  DeferredGlobalLight.slh
//  libraries/render-utils/src
//
//  Created by Sam Gateau on 2/5/15.
//  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_GLOBAL_LIGHT_SLH@>
<@def DEFERRED_GLOBAL_LIGHT_SLH@>

<@include model/Light.slh@>
<@include DeferredLighting.slh@>

<@func declareSkyboxMap()@>
// declareSkyboxMap
uniform samplerCube skyboxMap;

vec4 evalSkyboxLight(vec3 direction, float lod) {
    // textureQueryLevels is not available until #430, so we require explicit lod
    // float mipmapLevel = lod * textureQueryLevels(skyboxMap);
    return textureLod(skyboxMap, direction, lod);
}
<@endfunc@>

<@func prepareGlobalLight()@>
    // prepareGlobalLight

    // Transform directions to worldspace
    vec3 fragNormal = vec3(invViewMat * vec4(normal, 0.0));
    vec3 fragEyeVector = vec3(invViewMat * vec4(-position, 0.0));
    vec3 fragEyeDir = normalize(fragEyeVector);

    // Get light
    Light light = getLight();

    vec4 shading = evalFragShading(fragNormal, -getLightDirection(light), fragEyeDir, metallic, vec3(metallic), roughness);
    color = vec3(albedo * shading.w + shading.rgb) * min(shadowAttenuation, obscurance) * getLightColor(light) * getLightIntensity(light);
    color += emissive;
<@endfunc@>

<@func declareEvalAmbientGlobalColor()@>
vec3 evalAmbientGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal, vec3 albedo, float metallic, vec3 emissive, float roughness) {
    <$prepareGlobalLight()$>
    color += albedo * getLightColor(light) * obscurance * getLightAmbientIntensity(light);
    return color;
}
<@endfunc@>

<@func declareEvalAmbientSphereGlobalColor()@>
vec3 evalAmbientSphereGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal, vec3 albedo, float metallic, vec3 emissive, float roughness) {
    <$prepareGlobalLight()$>
    color += albedo * evalSphericalLight(getLightAmbientSphere(light), fragNormal).xyz * obscurance * getLightAmbientIntensity(light);
    return color;
}
<@endfunc@>

<@func declareEvalSkyboxGlobalColor()@>
<$declareSkyboxMap()$>
vec3 evalSkyboxGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal, vec3 albedo, float metallic, vec3 emissive, float roughness) {
    <$prepareGlobalLight()$>

    vec3 direction = -reflect(fragEyeDir, fragNormal);
    float lod = min(1.0 + floor((1.0 - gloss) * levels), levels);
    vec4 skyboxLight = evalSkyboxLight(direction, lod);
    color += albedo * skyboxLight.rgb * skyboxLight.a * obscurance * getLightAmbientIntensity(light);

    return color;
}
<@endfunc@>

<@func declareEvalLightmappedColor()@>
vec3 evalLightmappedColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 normal, vec3 albedo, vec3 lightmap) {
vec3 evalLightmappedColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 normal, vec3 diffuse, vec3 lightmap) {
    Light light = getLight();

    // Catch normals perpendicular to the projection plane, hence the magic number for the threshold
    // It should be just 0, but we have inaccuracy so we overshoot
    const float PERPENDICULAR_THRESHOLD = -0.005;
    vec3 fragNormal = vec3(invViewMat * vec4(normal, 0.0)); // transform to worldspace
    float diffuseDot = dot(fragNormal, -getLightDirection(light));
    float facingLight = step(PERPENDICULAR_THRESHOLD, diffuseDot); 

    // Reevaluate the shadow attenuation for light facing fragments
    float lightAttenuation = (1 - facingLight) + facingLight * shadowAttenuation;

    // Diffuse light is the lightmap dimmed by shadow
    vec3 diffuseLight = lightAttenuation * lightmap;

    // Ambient light is the lightmap when in shadow
    vec3 ambientLight = (1 - lightAttenuation) * lightmap * getLightAmbientIntensity(light); 

    return  obscurance * albedo * (diffuseLight + ambientLight);
}
<@endfunc@>

<@endif@>