Objects going at fast speeds phase through other objects.

Objects going even a little fast can make it go through other objects, such as a player falling,


or something going at a fast speed into a player or other objects,

or a player running through walls when having a high walking speed.

All these can be bad for separate or joined reasons, a player falling through a floor is quite bad as some games may have falling sections but don’t expect the player to die or maybe the area under is for a later section, maybe it irritates the player a little. Something going through something else at a high speed is bad as it can make things that need to be fast such as catapults or vehicles a tricky slope as this can make them not viable or take tons more effort. A player with a high walking speed being able to phase through walls is something I have encountered in games quite a bit, trivializes any sort of wall trying to contain the player unless the developer makes the wall insanely thick which can be look bad or not work depending on where it is, and once again it can kill a player when a player isn’t supposed to die. For a platform that is also a physics engine, it confuses me how something like this has not been patched or subsidized, especially with how popular this platform has become. I am someone who enjoys messing around with physics on roblox related things such as catapults, seeing how fast I can get something to move in certain games, but stuff like this adds a big headache to anything that is related to something going fast or being put high up and falling back down.

There are many posts about this topic already.
Ball falls through part at high velocity

Games with fast moving components may be using raycasting to determine if a player or object is approaching a surface and calculate collisions that way.

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This is a common problem with step-solver style physics engines. This bug is a known issue and has been reduced with many of Roblox’s physics performance optimizations. Unfortunately I don’t think it will ever be completely solved unless the fundamentals of the engine are changed.

Fun side note, this “tunneling problem” in step-engines is noticed in real life physics as well, but happens for other reasons. (Quantum tunneling)

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Thanks for the report! As others have mentioned, this is a known problem innate to the current collision detection system. If you want things to both move fast and collide, unfortunately you will just have to make them thick in the direction in which they move, at least for now. That said, this thickness should only need to linearly scale with the speeds you’re trying to achieve; you should only need an insanely thick wall for a correspondingly insanely high speed.

Eventually, we hope to avoid these problems with a continuous collision detection system, but if and when they happens isn’t set in stone yet.

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roblox needs to revamp their entire physics engine cuz it sucks so bad, especially for a physics game enjoyer like myself