Is it possible to create a cavity in a mesh collision?

i made a big static mesh, Its supposed to be a floating rock with a cave inside. I made a simplified version of it for collision and named it UCX_bigrock. In the world its floating so i couldn’t have just made it out of terrain. The issue is UE4 deletes the cave part. it keeps the custom collision i made, but it just stitched up the opening for the cave and now its a flat surface. There are no holes in the mesh, its like if you took a play dough cube and pushed your finger in it, its still intact, theres just a cavity in it. i could understand why you wouldnt want this if you were say making a vase or an open box but this mesh is big enough for me to walk around on. i can see the entrance and everything but its closed up. if at all possible, how can i make ue4 keep the collision mesh i made, as is?

  1. make sure that you have disable “one convex hull per…” and “auto generate collision” in your import settings
  2. just use a per poly collision → in the static mesh editor in the details panel set the collision mode to “use complex as simple” :slight_smile:

Oh that’s what use complex as simple means! I’d been wondering about that. :slight_smile:

Thank You! Works perfectly