directx - 使用 directx9 或 DX11 实现区域光

Question

我想使用 Directx 9 实现 AreaLight 请帮助我了解如何开始。我研究了两个三个链接，但可以在 RenderMonkey 或 Direct With Sample 中实现

Answer 1

球面光 HLSL

float specTrowbridgeReitz(float HoN,float a,float aP)
{
   float a2 = a*a;
   float ap2 = aP*aP;
   return ( a2 * ap2 ) / pow( HoN * HoN * ( a2 - 1.0 ) + 1.0, 2.0 );
}

float visSchlickSmithMod( float NoL, float NoV, float r )
{
    float k = pow( r * 0.5 + 0.5, 2.0 ) * 0.5;
    float l = NoL * ( 1.0 - k ) + k;
    float v = NoV * ( 1.0 - k ) + k;
    return 1.0 / ( 4.0 * l * v );
}

float fresSchlickSmith( float HoV, float f0 )
{
   return f0 + ( 1.0 - f0 ) * pow( 1.0 - HoV, 5.0 );
}

float sphereLight(float3 pos,float3 N,float3 V,float3 r,float f0,float 
roughness,float NoV,out float NoL)
{
   float3 L = lightPositions - pos;
   float3 centerToRay = dot(L,r)*r-L;
   float3 closestPoint = L + centerToRay * clamp( fLightRadius / length( 
   centerToRay ), 0.0, 1.0 );
   float3 l = normalize(closestPoint);
   float3 h = normalize(V+l);
   NoL = clamp(dot(N,l),0.0,1.0);
   float HoN = clamp(dot(h,N),0.0,1.0);
   float HoV = dot(h,V);
   float distL = length(L);
   float alpha = roughness * roughness;
   float alphaPrime = clamp(fLightRadius/(distL*2.0)+alpha,0.0,1.0);
   float specD = specTrowbridgeReitz( HoN, alpha, alphaPrime );
   float specF = fresSchlickSmith( HoV, f0 );
   float specV = visSchlickSmithMod( NoL, NoV, roughness );
   return specD * specF * specV*NoL;
}

float3 areaLights(float3 pos,float3 nor,float3 V)
{
   float f0 = FO;
   float NoV = clamp(dot(nor,V),0.0,1.0);
   float3 r = reflect(-V,nor);
   float NdotLSphere;
   float specSph = sphereLight(pos,nor,V,r,f0,roughness,NoV,NdotLSphere);
   float3 color = 0.3183*(NdotLSphere*lightcolor)+
   (specSph*lightcolor)+albedo;
   return pow(color,1.0/2.2);
}

float4 ps_main( PS_INPUT Input ) : COLOR0
{  
    float3 N = normalize(Input.Normal);
    float3 viewDir = normalize(campos.xyz - 
    float3(Input.WSPosition.xyz));
    float3 color = areaLights(Input.WSPosition,N,viewDir);
    return float4(color,0.0);
 }