vecLightPos[8]
vecLightViewPos[8]
vecLightColor[8]

Type

Remarks

• In an average vs 1.1 shader, the maximum number of instructions is only sufficient for calculating about 6 dynamic lights. Higher shader versions can theoretically support 30 or more simultaneous dynamic lights.
• Use only active lights with a nonzero range for light calculation. Up to version 6.41, active lights can be at every array position. From version 6.41 on, the active lights are sorted to the beginning of the array.
• Because the vecLightPos.w component contains the range, use only the vecLightPos.xyz components for matrix multiplications.
• vecLightViewPos (6.41 or above) contains the light positions transformed into view space.

Example

// Use dynamic lights in a vertex shader

  float4 vecLightPos[8];
  float4 vecLightColor[8];
  ...

// return the dynamic light on the surface
  float4 DoPointLight(float3 P, float3 N, int i)
  {
// calculate the light ray pointing from the light to the surface
    float3 D = (float3)vecLightPos[i]-P;
// calculate the angle between surface and light ray
    float NdotL = dot(N,normalize(D));
// modulate the light by the surface angle
    float4 Color = vecLightColor[i] * NdotL;

// calculate the light attenuation factor
    float fac = 0.f;
    if (NdotL >= 0.f && vecLightPos[i].w > 0.f)
    {
// get the distance factor
      float LD = length(D)/vecLightPos[i].w;
      if (LD < 1.f)
        fac = 1.f - LD;
    }
    return Color * fac;
  }

  VS_OUT TerrainLight_VS (
    float4 inPos : POSITION,
    float3 inNormal : NORMAL)
  {
    VS_OUT Out;

// transform the vector position to screen coordinates
    Out.Pos = mul(inPos,matWorldViewProj);

// Terrains don't need to rotate the normal, but it must be normalized
    float3 N = normalize(inNormal);
    float3 P = mul(inPos,matWorld);

// Add 6 dynamic lights (maximum for vs 1.1)
    Out.Color = float4(0.f,0.f,0.f,0.f);
    for (int i=0; i<6; i++)
      Out.Color += DoPointLight(P,N,i);
    ...
    return Out;
  }

See also: