#ifndef UNITY_COMMON_LIGHTING_INCLUDED
#define UNITY_COMMON_LIGHTING_INCLUDED

//-----------------------------------------------------------------------------
// Attenuation functions
//-----------------------------------------------------------------------------

// Ref: Moving Frostbite to PBR
float SmoothDistanceAttenuation(float squaredDistance, float invSqrAttenuationRadius)
{
	float factor = squaredDistance * invSqrAttenuationRadius;
	float smoothFactor = saturate(1.0f - factor * factor);
	return smoothFactor * smoothFactor;
}

#define PUNCTUAL_LIGHT_THRESHOLD 0.01 // 1cm (in Unity 1 is 1m)

float GetDistanceAttenuation(float3 unL, float invSqrAttenuationRadius)
{
	float sqrDist = dot(unL, unL);
	float attenuation = 1.0f / (max(PUNCTUAL_LIGHT_THRESHOLD * PUNCTUAL_LIGHT_THRESHOLD, sqrDist));
	// Non physically based hack to limit light influence to attenuationRadius. 
	attenuation *= SmoothDistanceAttenuation(sqrDist, invSqrAttenuationRadius);

	return attenuation;
}

float GetAngleAttenuation(float3 L, float3 lightDir, float lightAngleScale, float lightAngleOffset)
{
	float cd = dot(lightDir, L);
	float attenuation = saturate(cd * lightAngleScale + lightAngleOffset);
	// smooth the transition
	attenuation *= attenuation;

	return attenuation;
}

#endif // UNITY_COMMON_LIGHTING_INCLUDED