I don't believe Bullet provides sub-substep timing of collision events. My advice would be: try to take shorter substeps and perform all add/remove/update operations between substeps. I don't think it is a good idea to rely on the order of operations during the substep to perform mid-substep 'disabling' of objects, especially in a multi-user environment. CCD is off by default but can be enabled on a per-object basis. Note, you'll probably want to enable continuous collision detection (CCD) for these fast physical bullets. Then, if they manage to not hit anything during their first substep reset their velocity to what it really should be on the next substep. Instead of advancing bullets to where they would be at the beginning of the substep, create them where they were supposedly fired (mid previous substep) but give them higher velocity computed Just Right to put them where they should be at the end of the substep. I don't know if it actually works because I only just thought of it. If you're really worried about 'tunnelling' because of extrapolated bullet creation behind nearby targets then here is an idea. Instead: at the beginning of each subframe add the fresh bullets in the right spots after you've done all of your math and logic. Sorry for the wall of text, English is not my native language, so I tried to be precise, but lacking the vocabulary to be concise. Other great bonuses would be local slowmo, a parabolic or eliptical raycast function, and a function to get the interpolated position of an object for a given time, and implementation of the unity terrain collider and easy rollback for the server (terrifying prospect I know). Lastly, if a player is lagging behind, I should be able to slow the simulation for everyone until they catch up.

Basically only changes in force applied to objects should be broadcasted.

It's probably feasable, but I'm wondering how other people have fared implementing basic Dead Reckoning in Bullet. This is not exactly mandatory, I can deal with implementing that myself with callbacks, or using a limited number of teams. Ideally I should be able to dynamically create new masks for each team. Some projectiles may pass through friendly units, but not enemy ones. I should also be able to deduce the exact time that a collision happened from the callbacks. This means technically that collisions should be resolved in order, however this only needs to happen locally. Ideally the solver should be able to realize that a collider is dead during resolution, so that other projectiles may pass through. Ideally, I should be able to tell the solver that a item x is only to be simulated from an exact time t.Ĭollisions can destroy Shields and targets, which are instantly removed from the game. The problem is that the raycast method doesn't allow me to do complex collisions resolution, and if a target moves close enough right after the raycast, they might be missed by the bullet entirely. The logic allows me to be frame-rate independent, but I have to use a raycast for the first few meters, and spawn the object further from me. Because of that, I have to interpolate the origin of each object considering the velocity and gravity of the player, but also pretend that the bullets were fired slightly earlier than the current frame.

I have weapons that can fired hundreds of time per second, shot by players moving rapidly. I recently gave up on the unity physics engine due to a lack of possible customization. I'm currently developing a physics-based multiplayer game for mid range hardware on Unity.

Play bullet force unity