DX灯光笔记

平行光：和光源方向有关，和位置无关

Lambert余弦=dot(n,l)

点光源：和光源方向无关，和位置有关

简单的线性算法：Lambert余弦(d:强度 E:EndAttenuation 点到光源的距离 s:StartAttenuation 衰减半径，超过这个距离开始衰减)

影响因子算法：

c:常数衰减因子

i:线性衰减因子

q:平分衰减因子

d:受点与光源之前距离影响

聚光灯：

内外角

float3 LightVector = L.Position - InObjectWorldLocation;;
float Distance = length(LightVector);

if (Distance < L.EndAttenuation)
{	
	float DotValue = max(dot(NormalizeLightDirection, L.LightDirection), 0.f);
	//float4 LightStrength = float4(1.f, 1.f, 1.f, 1.f) * pow(DotValue,1.f);
	
	float4 LightStrength = float4(1.f, 1.f, 1.f, 1.f) * float4(L.LightIntensity, 1.f);
	
	float Theta1 = acos(DotValue);
	if (Theta1 == 0.f)
	{
		return LightStrength;
	}
	else if (Theta1 <= L.ConicalInnerCorner)
	{
		return LightStrength;
	}
	else if (Theta1 <= L.ConicalOuterCorner)
	{
		float OuterInnerDistance = L.ConicalOuterCorner - L.ConicalInnerCorner;
		float CurrentDistance = OuterInnerDistance - (Theta1 - L.ConicalInnerCorner);

		return (CurrentDistance / OuterInnerDistance) * LightStrength;
		////return AttenuationPointLights1(L, Distance) * LightStrength;
		//return AttenuationPointLights2(
		//	L,
		//	Distance,
		//	0.f,//c
		//	0.4f,//i
		//	0.3f) * LightStrength;//q
	}
}