So I've implemented multiple point-lights with shadowmapping using forward rendering..
The performance is horrible though. I *do* use a cubemap to reduce texture() fetches, but even then I can only get about 6 lights before I start running around 100-150 FPS (down from 200-300).. Even if the lights aren't on screen, like if I'm in a corner staring at a wall.
I also know that when doing multiple *lights* like this, you basically need to do deferred rendering for decent performance, although I don't know much specific details about deferred rendering.
Now, what I'm really curious about is specifically whether the *shadow-mapped* part of the point lights will be faster with deferred rather than forward?
I mean, from my understanding - the slowdown is mainly due to all the texture() fetches for each shadow-mapped light.... But - will deferred rendering still basically do the same thing?
If not, and it *is* considerably faster, what are some of the details?
For example, I've seen it's possible to do basically hundreds of lights with deferred rendering... But how many *shadow-mapped* lights can you get away with?
If it *is* worth it and deferred shadow-mapped lighting is *fast* - then, then please provide any decent links you may have to guides about both simple deferred rendering and shadow-mapped deferred lighting.