I have a mesh from the “Post Apocalyptic” construction set from the UE marketplace. I place this mesh in a world and then scale it up and down. The collision volumes in the mesh do not scale with the mesh correctly. This makes scaling such a mesh impossible.
The included video shows the effect link text
This happens only when the meshes are scaled non-uniformly. When scaled with the same factor on all 3 axes, it seems to be ok.
I noticed this while walking up the stairs in this mesh. While it was possible before, the character now stumbles at the top and falls through the mesh (scaling 1.5/1.5/1.2)
It happens always.
I made a small stair model with a slope for the collision, just as that asset uses it.
Import it into an empty project, place it and then scale the resulting SM-Actor in the XY plane with the Z axis a different value while having “show collision” on in the viewport.
You will see that the collision plane will not scale in such a way that the top stair remains covered which leads to a fallthrough situation in this specific case, but of course there can be other collision problems as well.
It looks to me as if the collision volume is not scaled at all in this case. Stretch the stairs extremely on the length axis and you see what I mean
I believe that this issue is related to the particular type of collision that you were using on your stair mesh. What I did was go into the Static Mesh Editor, and click the Collision button on the top toolbar. Then, I selected Remove Collision.
After doing so, I selected the Auto Convex Collision option to create a more accurate collision. This type seemed to scale as expected when I scaled the stair mesh, so go ahead and give that a try.
Let me know if that gets you your desired results.
Hey, no, that wont do in most cases. The separate stair was just an example. You could not use that solution in the original asset from your store for instance because that is a complete house level with rooms, doorways etc. These things need to have their collision data set by hand and that asset uses a slope on the stairs that’s why I created the sample asset.
The original problem still exists with more complex meshes and can’t be solved this way
I have build a scene with several props. These items have their own custom made collision data. My particular scene is a house interior.
In order to make things fit it is sometimes necessary to scale objects like a floor piece so that it fills out small spaces.
Once you do that, go into “Merge Actor” and merge those items into a new static mesh with “merge Physics Data”.
When done, the new static mesh will have the collision data of the original, unscaled objects, meaning that the resulting mesh looks optically ok, but has collision errors. This basically makes the Merge Actor feature useless when working with scaled meshes
After this happened to me, I really think this is a bug that should be looked into by the developers.