I am working on chutes that rely on collisions between balls and a mesh. The tan chute, on the right, is a mesh part with collisions set to precise. And the gray chute, on the left, is a collection of parts in order to achieve good collisions in a curved section of track.
They are visually perfectly aligned, but the balls are hitting something. Must be a collision issue with the mesh, right?
Well, after turning on the decomposition geometry to make sure nothing is wrong with the collider, I see that the collision geometry is perfectly aligned as well!
This is very inconvenient, because I was relying on the ability to smoothly transition between these two sections of track!
Expected behavior
I expect the decomposition geometry setting to accurately depict the REAL colliders for objects. I need to be able to trust what I am seeing, so I don’t waste any time doing something that isn’t actually possible.
Hello thank you for reporting this. Can you please try overlapping the ends of the chutes a bit (extrude the ends) instead of perfectly aligning the where they meet.
yes that is correct. With the current convex decomposition, a collision margin is added to the mesh that makes the collision not match exactly with the input mesh. This is more obvious in this case as you are transitioning from a box to a mesh near the jump.
A couple of possible solutions:
tilt the tube slightly left to make the transition smooth.
use one collision type (boxes shaped as a tube or meshes) all around. This should help hide the margin difference between the collision types.
I know I’m bumping this thread but this is quite an important issue. I’ve just spent the past hour and a half trying to figure out why my collision geometry for a road is elevating on the second segment that I’ve imported, then I came across this post.
I thought “Show Decomoposition Geometry” would provide me with EXACTLY what the collisions will be in run-time, but it doesn’t. To put it into perspective I’ve had to lower the second segment by 0.09 studs to achieve the same collision height as the first segment. This might not seem like a lot but when you’ve got vehicles moving over it at speed, it causes a severe impact whilst trying to keep the car stable.
Just to put that into perspective this is after I’ve adjusted the height manually after wasting time with trial and error:
I hope this can be rectified because it’s a bit misleading and makes development with meshes even more of a pain, as if it wasn’t already bad enough
Hi,
my team is working on fixing issues with our legacy convex decomposition algorithms.
Would you be able to DM me the model of the chutes or a (simplified) place file showing this bug - so we can diagnose the issue.
Thank you!
