Directx Lighting Question

I think you mean the fixed function pipeline of directx supports 8 lights.

One word answer: shaders

8 lights at a time means 8 lights enabled simultaneously. This doesn't mean that your entire scene is limited to 8 lights. You can either use additive blending, or select the best 8 lights for every mesh (your scene will use more than 8 lights in total).

P.S.: I said "8 lights" too much =/

Additionally you can use unlimited fixed function lights in d3d9 if you create a software vertex device. If you are able to create a hardware vertex processing device, I would use jpventoso's suggestions. If you have to fallback to a software processing device however, you don't have to worry about this stuff (although for optimization purposes you probably want to cull away as many lights as possible considering that you are probably on some old or crappy intel integrated hardware if you have to fallback to software).

If u'are looking for the way to placing more lights on your scenes, i strongly suggest u use deferred lighting technique.

In this technique , the shading of point lights becomes post-screen effect. Theoretically , this is no limitation for the light number .

Here , i've just finished a demo of deferred lighting, hope it could help.

http://codeboycjy.blogbus.com/