Collision Polygonal Limit for MeshParts

collision
mesh-collision

#1

Hello everyone. I was looking into creating a slope mesh for my project, and I came across the discrepancy between MeshPart appearance and collision. As seen below, the collision for the mesh is limited for efficiency, but it can cause some issues such as “floating”.

image

For convenience, I was wondering if there’s a specific polygonal limit for the collision put on a MeshPart. That way, I can work around it and set the mesh’s triangle count below the limit, so there would not be any issues between the appearance and collision of objects such as a slope.


#2

Its not ideal but could you split the mesh for now and group them together in Studio?

This really does need solving though.


#3

There’s no hard limit like you’re describing as far as I’m aware - it depends on the geometry of your mesh. The floating behavior you’re describing can occur around concave regions of the mesh because the convex decomposition (splitting a concave mesh into convex chunks) that Roblox performs is an approximation.

You can switch on ShowDecompositionGeometry in Studio settings to see the physical model of the mesh in Roblox. If you want to learn more about the backend implementation, Roblox uses the ConvexDecomposition library from Bullet.


#4

Thanks! I’ll look into that. If I can’t find anything there then I’ll just try to apply my own angular limits or a simpler geometry to see if that works.