<!
//  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 graphics/Light.slh@>

<@include LightingModel.slh@>
<$declareLightBuffer()$>
<$declareLightAmbientBuffer()$>

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

<@func fetchGlobalLight()@>
    // Get light
    Light light = getKeyLight();
    LightAmbient lightAmbient = getLightAmbient();
    
    vec3 lightDirection = getLightDirection(light);
    vec3 lightIrradiance = getLightIrradiance(light);

    vec3 color = vec3(0.0);
<@endfunc@>

<@func prepareGlobalLight(positionES, normalWS)@>
    // prepareGlobalLight
    // Transform directions to worldspace
    vec3 fragNormalWS = vec3(<$normalWS$>);
    vec3 fragPositionWS = vec3(invViewMat * vec4(<$positionES$>, 1.0));
    vec3 fragEyeVectorWS = invViewMat[3].xyz - fragPositionWS;
    vec3 fragEyeDirWS = normalize(fragEyeVectorWS);

    <$fetchGlobalLight()$>

<@endfunc@>


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

<@func declareEvalAmbientSphereGlobalColor(supportScattering)@>

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

<@if supportScattering@>
<$declareDeferredCurvature()$>
<@endif@>

vec3 evalAmbientSphereGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal,
vec3 albedo, vec3 fresnel, float metallic, float roughness
<@if supportScattering@>
    , float scattering, vec4 midNormalCurvature, vec4 lowNormalCurvature
<@endif@> ) {

    <$prepareGlobalLight(position, normal)$>

    SurfaceData surfaceWS = initSurfaceData(roughness, fragNormalWS, fragEyeDirWS);

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, lightAmbient, surfaceWS, metallic, fresnel, albedo, obscurance
<@if supportScattering@>
    ,scattering, midNormalCurvature, lowNormalCurvature
<@endif@> );
    color += ambientDiffuse;
    color += ambientSpecular;


    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, lightDirection, lightIrradiance, surfaceWS, metallic, fresnel, albedo, shadowAttenuation
<@if supportScattering@>
    ,scattering, midNormalCurvature, lowNormalCurvature
<@endif@> );
    color += directionalDiffuse;
    color += directionalSpecular;

    return color;
}

<@endfunc@>

<@include Haze.slh@>

<@func declareEvalSkyboxGlobalColor(supportScattering)@>

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

<@if supportScattering@>
<$declareDeferredCurvature()$>
<@endif@>

vec3 evalSkyboxGlobalColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 position, vec3 normal,
    vec3 albedo, vec3 fresnel, float metallic, float roughness
<@if supportScattering@>
    , float scattering, vec4 midNormalCurvature, vec4 lowNormalCurvature
<@endif@>
    ) {
    <$prepareGlobalLight(position, normal)$>

    SurfaceData surfaceWS = initSurfaceData(roughness, fragNormalWS, fragEyeDirWS);

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, lightAmbient, surfaceWS, metallic, fresnel, albedo, obscurance
<@if supportScattering@>
    ,scattering, midNormalCurvature, lowNormalCurvature 
<@endif@>
    );
    color += ambientDiffuse;
    color += ambientSpecular;

    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, lightDirection, lightIrradiance, surfaceWS, metallic, fresnel, albedo, shadowAttenuation
<@if supportScattering@>
    ,scattering, midNormalCurvature, lowNormalCurvature
<@endif@>
    );
    color += directionalDiffuse;
    color += directionalSpecular;

    // Attenuate the light if haze effect selected
    if ((isHazeEnabled() > 0.0) && (hazeParams.hazeMode & HAZE_MODE_IS_KEYLIGHT_ATTENUATED) == HAZE_MODE_IS_KEYLIGHT_ATTENUATED) {
        color = computeHazeColorKeyLightAttenuation(color, lightDirection, fragPositionWS);    
    }

    return color;
}

<@endfunc@>

<@func declareEvalLightmappedColor()@>
vec3 evalLightmappedColor(mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 normal, vec3 albedo, vec3 lightmap) {
    Light light = getKeyLight();
    LightAmbient ambient = getLightAmbient();

    // 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 = (1.0 - 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 = (1.0 - lightAttenuation) * lightmap * getLightAmbientIntensity(ambient);

    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, vec3 fresnel, float metallic, vec3 emissive, float roughness, float opacity, vec3 prevLighting) {
    <$prepareGlobalLight(position, normal)$>
    
    SurfaceData surfaceWS = initSurfaceData(roughness, fragNormalWS, fragEyeDirWS);

    color = prevLighting;
    color += emissive * isEmissiveEnabled();

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, lightAmbient, surfaceWS, metallic, fresnel, albedo, obscurance);
    color += ambientDiffuse;

    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, lightDirection, lightIrradiance, surfaceWS, metallic, fresnel, albedo, shadowAttenuation);
    color += directionalDiffuse;
    color += evalSpecularWithOpacity(ambientSpecular + directionalSpecular, opacity);

    return color;
}
<@endfunc@>

<@func declareEvalGlobalLightingAlphaBlendedWithHaze()@>

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

vec3 evalGlobalLightingAlphaBlendedWithHaze(
    mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 positionES, vec3 normalWS, 
    vec3 albedo, vec3 fresnel, float metallic, vec3 emissive, float roughness, float opacity) 
{
    
    <$prepareGlobalLight(positionES, normalWS)$>
    
    SurfaceData surfaceWS = initSurfaceData(roughness, fragNormalWS, fragEyeDirWS);

    color += emissive * isEmissiveEnabled();

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, lightAmbient, surfaceWS, metallic, fresnel, albedo, obscurance);
    color += ambientDiffuse;

    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, lightDirection, lightIrradiance, surfaceWS, metallic, fresnel, albedo, shadowAttenuation);
    color += directionalDiffuse;
    color += evalSpecularWithOpacity(ambientSpecular + directionalSpecular, opacity);

    // Haze
    if ((isHazeEnabled() > 0.0) && (hazeParams.hazeMode & HAZE_MODE_IS_ACTIVE) == HAZE_MODE_IS_ACTIVE) {
        vec4 hazeColor = computeHazeColor(
            positionES,                     // fragment position in eye   coordinates
            fragPositionWS,                 // fragment position in world coordinates
            invViewMat[3].xyz,              // eye      position in world coordinates
            lightDirection                  // keylight direction vector in world coordinates
        );

        color = mix(color.rgb, hazeColor.rgb, hazeColor.a);
    }

    return color;
}

vec3 evalGlobalLightingAlphaBlendedWithHaze(
    mat4 invViewMat, float shadowAttenuation, float obscurance, vec3 positionES, vec3 positionWS, 
    vec3 albedo, vec3 fresnel, float metallic, vec3 emissive, SurfaceData surface, float opacity, vec3 prevLighting) 
{
    <$fetchGlobalLight()$>
    
    color = prevLighting;
    color += emissive * isEmissiveEnabled();

    // Ambient
    vec3 ambientDiffuse;
    vec3 ambientSpecular;
    evalLightingAmbient(ambientDiffuse, ambientSpecular, lightAmbient, surface, metallic, fresnel, albedo, obscurance);

    // Directional
    vec3 directionalDiffuse;
    vec3 directionalSpecular;
    evalLightingDirectional(directionalDiffuse, directionalSpecular, lightDirection, lightIrradiance, surface, metallic, fresnel, albedo, shadowAttenuation);

    color += ambientDiffuse + directionalDiffuse;
    color += evalSpecularWithOpacity(ambientSpecular + directionalSpecular, opacity);

    // Haze
    if ((isHazeEnabled() > 0.0) && (hazeParams.hazeMode & HAZE_MODE_IS_ACTIVE) == HAZE_MODE_IS_ACTIVE) {
        vec4 hazeColor = computeHazeColor(
            positionES,                     // fragment position in eye   coordinates
            positionWS,                     // fragment position in world coordinates
            invViewMat[3].xyz,              // eye      position in world coordinates
            lightDirection                  // keylight direction vector
        );

        color = mix(color.rgb, hazeColor.rgb, hazeColor.a);
    }

    return color;
}
<@endfunc@>


<@endif@>