<!
//  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@>!>

<@include LightingModel.slh@>
<$declareLightingModel()$>

<@include LightAmbient.slh@>
<@include LightDirectional.slh@>


<@func prepareGlobalLight(isScattering)@>
    // prepareGlobalLight
    // Transform directions to worldspace
    vec3 fragNormal = vec3((normal));
    vec3 fragEyeVector = vec3(invViewMat * vec4(-position, 0.0));
    vec3 fragEyeDir = normalize(fragEyeVector);

    // Get light
    Light light = getLight();
    
    vec3 color = vec3(0.0);
    
<@if isScattering@>
<@else@>
    color += emissive * isEmissiveEnabled();
<@endif@>

    vec3 fresnel = vec3(0.03); // Default Di-electric fresnel value
    if (metallic > 0.5) {
        fresnel = albedo;
        metallic = 1.0;
    }

<@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(supportScattering)@>

<$declareLightingAmbient(1, 0, 0, supportScattering)$>
<$declareLightingDirectional(supportScattering)$>

vec3 evalAmbientSphereGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal,
    vec3 albedo, float metallic, vec3 emissive, float roughness) {

    <$prepareGlobalLight()$>

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, obscurance);
    color += ambientDiffuse * isDiffuseEnabled() * isAmbientEnabled();
    color += ambientSpecular * isSpecularEnabled() * isAmbientEnabled();


    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, shadowAttenuation);
    color += directionalDiffuse * isDiffuseEnabled() * isDirectionalEnabled();
    color += directionalSpecular * isSpecularEnabled() * isDirectionalEnabled();

    return color;
}

<@if supportScattering@>

<$declareDeferredCurvature()$>

vec3 evalAmbientSphereGlobalColorScattering(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal,
    vec3 albedo, float metallic, vec3 emissive, float roughness, float scattering, vec4 midNormalCurvature, vec4 lowNormalCurvature) {

    <$prepareGlobalLight(1)$>

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbientScattering(ambientDiffuse, ambientSpecular, light,
        fragEyeDir, fragNormal, roughness,
        metallic, fresnel, albedo, obscurance,
        isScatteringEnabled() * scattering, midNormalCurvature, lowNormalCurvature);
    color += ambientDiffuse * isDiffuseEnabled() * isAmbientEnabled();
    color += ambientSpecular * isSpecularEnabled() * isAmbientEnabled();


    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectionalScattering(directionalDiffuse, directionalSpecular, light,
        fragEyeDir, fragNormal, roughness,
        metallic, fresnel, albedo, shadowAttenuation,
        isScatteringEnabled() * scattering, midNormalCurvature, lowNormalCurvature);
    color += directionalDiffuse * isDiffuseEnabled() * isDirectionalEnabled();
    color += directionalSpecular * isSpecularEnabled() * isDirectionalEnabled();

    return color;
}

<@endif@>

<@endfunc@>


<@func declareEvalSkyboxGlobalColor(supportScattering)@>

<$declareLightingAmbient(0, 1, 0, supportScattering)$>
<$declareLightingDirectional(supportScattering)$>

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

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, obscurance);
    color += ambientDiffuse * isDiffuseEnabled() * isAmbientEnabled();
    color += ambientSpecular * isSpecularEnabled() * isAmbientEnabled();


    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, shadowAttenuation);
    color += directionalDiffuse * isDiffuseEnabled() * isDirectionalEnabled();
    color += directionalSpecular * isSpecularEnabled() * isDirectionalEnabled();

    return color;
}

<@if supportScattering@>

<$declareDeferredCurvature()$>

vec3 evalSkyboxGlobalColorScattering(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal, vec3 albedo, float metallic, vec3 emissive, float roughness, float scattering, vec4 blurredCurvature, vec4 diffusedCurvature) {
    <$prepareGlobalLight(1)$>

        // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbientScattering(ambientDiffuse, ambientSpecular, light,
        fragEyeDir, fragNormal, roughness,
        metallic, fresnel, albedo, obscurance,
        isScatteringEnabled() * scattering, lowNormal, highCurvature, lowCurvature);
    color += ambientDiffuse * isDiffuseEnabled() * isAmbientEnabled();
    color += ambientSpecular * isSpecularEnabled() * isAmbientEnabled();

    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectionalScattering(directionalDiffuse, directionalSpecular, light,
        fragEyeDir, fragNormal, roughness,
        metallic, fresnel, albedo, shadowAttenuation,
        isScatteringEnabled() * scattering, , midNormalCurvature, lowNormalCurvature);
    color += directionalDiffuse * isDiffuseEnabled() * isDirectionalEnabled();
    color += directionalSpecular * isSpecularEnabled() * isDirectionalEnabled();

    return vec3(color);
}

<@endif@>

<@endfunc@>

<@func declareEvalLightmappedColor()@>
vec3 evalLightmappedColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 normal, vec3 albedo, 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  isLightmapEnabled() * obscurance * albedo * (diffuseLight + ambientLight);
}
<@endfunc@>


<@func declareEvalGlobalLightingAlphaBlended()@>

<$declareLightingAmbient(1, 1, 1)$>
<$declareLightingDirectional()$>

vec3 evalGlobalLightingAlphaBlended(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal, vec3 albedo, float metallic, vec3 emissive, float roughness, float opacity) {
    <$prepareGlobalLight()$>

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, obscurance);
    color += ambientDiffuse * isDiffuseEnabled() * isAmbientEnabled();
    color += ambientSpecular * isSpecularEnabled() * isAmbientEnabled() / opacity;


    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, light, fragEyeDir, fragNormal, roughness, metallic, fresnel, albedo, shadowAttenuation);
    color += directionalDiffuse * isDiffuseEnabled() * isDirectionalEnabled();
    color += directionalSpecular * isSpecularEnabled() * isDirectionalEnabled() / opacity;

    return color;
}

<@endfunc@>


<@endif@>