From seeing your comments, I can easily see that you aren't happy about the performance 
As other people recommended, you can check whether the object is affected by the light, here's how with a Point Light!
Bounding Spheres
Bounding Spheres is if you were to collect all the vertices in the mesh and make a sphere encapsulate them, like this:
RABBITS!
To get this result, you need two things:
- The center of the mesh
- The radius of the mesh from the center
Calculating the center:
- Declare the variable
- Loop over all your vertices and add them to the center
- Divide the center by the number of vertices.
- THAT'S IT!
D3DXVECTOR3 center = D3DXVECTOR3(0, 0, 0);
for(int v = 0; v < mVertices.size(); v++ )
{
center += mVertices[v];
}
center /= mVertices.size();
Calculating the radius: (With the center)
- Declare the variable
- Loop over all the vertices
- Get the distance between the vertices and the center
- Find the greatest length
float radius = 0.0f;
for (int v = 0; v < mVertices.size(); v ++)
{
D3DXVECTOR3 diff = mVertices[v] - center;
float length = sqrtf(D3DXVec3Dot(&diff, &diff));
if (length > radius)
radius = length;
}
To visualize the result, you just need to translate a sphere (or stuff) to this location: sphere->Translate(mesh->Position + mesh->Center), and also scale it by the meshes radius.
Testing for collision between Sphere-Sphere
As you know the point light has a radius, and so does, hopefully, the mesh with these calculations. To see if they collide, just do the following
- Find the vector between the mesh center and the point light's position.
- Get the length of that vector
- Check whether that length is smaller than both the point light's radius and the mesh's radius.
- If true, they collide!!!
D3DXVECTOR3 mDistance = mesh->center + pointLight.Position;
float d = sqrtf( D3DXVec3Dot( &mDistance, &mDistance) );
if (d < (mesh->BoundingSphere.radius + pointLight.Range) )
// They collide!!!
In other words, if they collide, the light will affect the mesh.
Mini Tutorials!
