Rasterization is sometimes used for primary rays. However, it limits greatly what you can do - depth of field, motion blur, participating media, refraction, only basic camera models, no adaptive or custom sampling, etc.


If you just want to explicitly sample an area light, then here's the general procedure you should follow. Pick light $i$ out of $L$ lights with some probability $p_i$ (the other probabilities being $p_1,...,p_L$, a light may be picked through inverse transform sampling). Pick a point $\pmb{y}$ on the surface of the light with some probability $q_i(\pmb{y})$. ...


There are renderes that do this. Most notably Pixars Renderman prefers to work this way. Hybrid renderers can work in other ways too... It used to be that hybrid renderers like this were quite common, they still are somewhat in software only implementations. They are slowly being replaced though by a new breed of trace only renderes though. Mostly the ...

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