Simple Bullet Shadowing Surfer
Yes, bullet shadows can be deleted, when the bullet casting shadow is destroyed before intersection happens.
However, I don’t think modeling this helps anything, since 1. we are already recalculating shadows when collision happens 2. the chance of actual collision is always low for normal battles. 3. You don’t know that chance exactly, an estimation may decrease performance actually.
To accurately model the chance of bullet getting destroyed before intersection happens, you should consider more than a flat probability — since once a bullet passes all other waves except target wave, the only chance bullet collision happening is with the target wave.
I don’t think this added complexity should outperform traditional way that updates shadows when collisions actually happen.