uniform vec3 ambientLightColor;

vec3 getAmbientLightIrradiance( const in vec3 ambientLightColor ) {

	vec3 irradiance = ambientLightColor;

	#ifndef PHYSICALLY_CORRECT_LIGHTS

		irradiance *= PI;

	#endif

	return irradiance;

}

#if NUM_DIR_LIGHTS > 0

	struct DirectionalLight {
		vec3 direction;
		vec3 color;

		int shadow;
		float shadowBias;
		float shadowRadius;
		vec2 shadowMapSize;
	};

	uniform DirectionalLight directionalLights[ NUM_DIR_LIGHTS ];

	void getDirectionalDirectLightIrradiance( const in DirectionalLight directionalLight, const in GeometricContext geometry, out IncidentLight directLight ) {

		directLight.color = directionalLight.color;
		directLight.direction = directionalLight.direction;
		directLight.visible = true;

	}

#endif


#if NUM_POINT_LIGHTS > 0

	struct PointLight {
		vec3 position;
		vec3 color;
		float distance;
		float decay;

		int shadow;
		float shadowBias;
		float shadowRadius;
		vec2 shadowMapSize;
		float shadowCameraNear;
		float shadowCameraFar;
	};

	uniform PointLight pointLights[ NUM_POINT_LIGHTS ];

	// directLight is an out parameter as having it as a return value caused compiler errors on some devices
	void getPointDirectLightIrradiance( const in PointLight pointLight, const in GeometricContext geometry, out IncidentLight directLight ) {

		vec3 lVector = pointLight.position - geometry.position;
		directLight.direction = normalize( lVector );

		float lightDistance = length( lVector );

		directLight.color = pointLight.color;
		directLight.color *= punctualLightIntensityToIrradianceFactor( lightDistance, pointLight.distance, pointLight.decay );
		directLight.visible = ( directLight.color != vec3( 0.0 ) );

	}

#endif


#if NUM_SPOT_LIGHTS > 0

	struct SpotLight {
		vec3 position;
		vec3 direction;
		vec3 color;
		float distance;
		float decay;
		float coneCos;
		float penumbraCos;

		int shadow;
		float shadowBias;
		float shadowRadius;
		vec2 shadowMapSize;
	};

	uniform SpotLight spotLights[ NUM_SPOT_LIGHTS ];

	// directLight is an out parameter as having it as a return value caused compiler errors on some devices
	void getSpotDirectLightIrradiance( const in SpotLight spotLight, const in GeometricContext geometry, out IncidentLight directLight  ) {

		vec3 lVector = spotLight.position - geometry.position;
		directLight.direction = normalize( lVector );

		float lightDistance = length( lVector );
		float angleCos = dot( directLight.direction, spotLight.direction );

		if ( angleCos > spotLight.coneCos ) {

			float spotEffect = smoothstep( spotLight.coneCos, spotLight.penumbraCos, angleCos );

			directLight.color = spotLight.color;
			directLight.color *= spotEffect * punctualLightIntensityToIrradianceFactor( lightDistance, spotLight.distance, spotLight.decay );
			directLight.visible = true;

		} else {

			directLight.color = vec3( 0.0 );
			directLight.visible = false;

		}
	}

#endif


#if NUM_RECT_AREA_LIGHTS > 0

	struct RectAreaLight {
		vec3 color;
		vec3 position;
		vec3 halfWidth;
		vec3 halfHeight;
	};

	// Pre-computed values of LinearTransformedCosine approximation of BRDF
	// BRDF approximation Texture is 64x64
	uniform sampler2D ltc_1; // RGBA Float
	uniform sampler2D ltc_2; // RGBA Float

	uniform RectAreaLight rectAreaLights[ NUM_RECT_AREA_LIGHTS ];

#endif


#if NUM_HEMI_LIGHTS > 0

	struct HemisphereLight {
		vec3 direction;
		vec3 skyColor;
		vec3 groundColor;
	};

	uniform HemisphereLight hemisphereLights[ NUM_HEMI_LIGHTS ];

	vec3 getHemisphereLightIrradiance( const in HemisphereLight hemiLight, const in GeometricContext geometry ) {

		float dotNL = dot( geometry.normal, hemiLight.direction );
		float hemiDiffuseWeight = 0.5 * dotNL + 0.5;

		vec3 irradiance = mix( hemiLight.groundColor, hemiLight.skyColor, hemiDiffuseWeight );

		#ifndef PHYSICALLY_CORRECT_LIGHTS

			irradiance *= PI;

		#endif

		return irradiance;

	}

#endif
