Character losing support when cresting a slope #415
Replies: 3 comments 5 replies
|
hm, that is a bit odd. First guess was indeed the bounding box expansion. Is something creating a body for the character with a low speculative margin? e.g. the Demos CharacterInput takes MinimumSupportContinuationDepth from the minimumSpeculativeMargin passed into it. Increasing the MinimumSupportContinuationDepth won't retroactively increase the body's own speculative margin, though. |
|
Character creation logic is as follows. Obviously probably need to share the margin on CollidableDescription and the character but as far as I'm aware 5f is being used for both (I couldn't get the code block to format properly so I just pasted images): 
I've attached a file with the character values at the time the character loses support and the expanded bounding box call if it's helpful. 
|
|
I don't see anything at a glance that would explain it; a repro in the demos might be useful? |
|
What do you mean by a repro in the demo? I can try and set up a similar scenario in the character demo, but to be honest it seems to function as expected in the demo. Cranking up velocity can cause the character to pop off the the lizard thing when it hits the top, and increasing the MinimumSpeculativeMargin seems to prevent that. Also two points of clarification/questions here: Am I correct in assuming that if I was to set the MinimumSpeculativeMargin to like 100000 the character in the demo would effectively never lose support unless I attempted to jump? |
|
I've set up a set up a scenario that seems basically the same in the character demo. I'll attach the file as a text file (just commented out a bunch of stuff and added in my custom terrain mesh, etc). If it's easier to just fork the repo or something I can do that as well. I don't seem to be losing support here (at least the same breakpoints aren't getting hit) which seems to suggest it is something on my end as expected. Just in case this is relevant, I'm using the 2.4.0 package via nuget for my actual application, although all the character logic is copied almost directly from the demos to the application. |
|
If the minimum speculative margin is very large (with the minimum support depth configured equivalently), and the AABB is expanded, yeah, it should maintain awareness of the floor and not lose traction if there's a contact with acceptably flat normal (not too steep). And yeah, can't actually look at the code to verify right now but iirc there's no position-level constraint on the vertical motion constraint, just velocity. It does try to counter separating velocity, though; that's how it can stay stuck to an elevator that suddenly drops down and similar. If the maximum glue force is low, that could explain the character leaving the ground, but with very large margins that doesn't imply losing traction. |
|
I have removed the linear damping on velocity in the narrow phase callbacks on the demo to more accurately reflect how my callbacks are working and it still seems to work in the demo. Character also seems to be losing support when crossing between two meshes next to each other (seems to be when it passes over the seam). Based on older forum posts it seems like the bounding box expansion was added to resolve this. I have confirmed again that the bounding box expansion is being called with the following values at the time of losing support: Character pose <29.027983, 7.2187176, 35.079315> The depths on the support candidates look something like this: All the issues would seem to indicate that something was off here, but I can't figure out what it is. Is there anything that would prevent the expanded bounding box from generating a contact manifold or just a simple contact? Seems like the demo allows the support depth to be much higher: |
|
that -3.4e38 is quite eyebrow raising! I don't know where that's coming from or how it would influence this issue, but it is odd. |
Uh oh!
There was an error while loading. Please reload this page.
Somewhat long question and I'm sure i'm misunderstanding something here...
I'm working with the CharacterController and can't seem to get my character to stay supported when cresting a slope/hill. My character has a capsule collision box and the terrain is made of a custom mesh (I have verified the triangles are correct and the character is not passing through the mesh at all). I know the character is technically not in contact with the mesh when it crests but I was under the impression that was what MinimumSupportContinuationDepth was for. It seems that AllowContactGeneration is getting hit and returning true in the NarrowPhaseCallbacks but ConfigureContactManifold is not on the frame it loses support. I have verified that the bounding box is getting expanded (which would explain why AllowContactGeneration is getting hit I think). Even jacking up the support depths to ridiculous levels seems to not change behavior. Copilot seems to think that no manifold is being generated because the capsule and mesh are not in contact, but that explanation did not make a lot of sense to me.
Any idea what I'm missing? I can post some code here if it is helpful. I've attached a video of what this looks like (character turns green when it loses support).
CharacterLosingSupport.mp4
All reactions