I'm new to computer graphics and I got some questions about lightmap.
This is the rendering equation,
[attachment=29030:render.png]
and if I use BRDF with
[attachment=29031:render (1).png]
I got,
[attachment=29032:render (2).png]
From my understanding, the diffuse part [attachment=29033:render (3).png] is view independent, so it could be precalculated.
But the specular part [attachment=29034:render (4).png] is view dependent, IBL could be used to handle indirect specular(https://seblagarde.wordpress.com/2011/08/17/hello-world/), but how about direct specular. could they be precomputed in practice?
Here lists some of my ideas.
1. The lightmap could store indirect light, all the direct light are computed from punctual light sources at runtime.
2. Store main light direction in the lightmap, use that direction to calulate specular reflection.
3. Store light source in the cubemap(IBL), not sure how to do that.