Hello! Does anyone have any ideas on how to make a collision mesh for a figure like this?
When I import the collision for it, it turns out like this:
For my task I really need this concavity in physics simulation, please help.
I know this is an old topic and you’ve probably already solved it, but I wanted to leave this for anyone who finds the thread later.
Unreal Engine generates simple collision for static meshes by default (unless you Import Custom Collision when you import a mesh). Simple collision is made of primitive shapes (boxes, spheres, capsules) or convex hulls (like your example above). A convex shape is one where any line drawn between two points on the shape stays entirely inside it. Because of that limitation, a curved ramp usually ends up with a single large collision shape that doesn’t follow the visible surface, so objects slide or float off it.
You can tell the mesh to use its actual triangle mesh for collision instead. Open the static mesh, go to the Collision section in the Details panel, and set Collision Complexity to Use Complex Collision as Simple. This is more expensive than simple collision, so it’s fine for a handful of important static objects but not something you want on everything. The mesh also has to stay static—you cannot enable Simulate Physics on an object using this setting. Other objects (and the player) can still collide with it.
A more efficient method is to build simplified collision that approximates the ramp. In your modeling software, create a series of boxes or convex shapes that follow the curve, then import them as custom collision (or generate them with Auto Convex Collision in the editor). It won’t match the visible mesh perfectly, but it’s usually accurate enough and much cheaper at runtime.