Movement Controller Intermittent Physics Issues + Slope Handling Problems

[vega]

Hello,

I've been running into some issues with the physics/movement controller and wanted to report them along with a reproducible example in hopes that we can get this fixed:

Issue 1: Intermittent Physics Breakdown on Game Start
Roughly every fifth or so launch of the game, the movement controller completely breaks down, and characters ignore or clip through walls and slopes. Restarting the game usually fixes it, but it keeps happening.

Issue 2: Slope Handling Causes Ground State Flickering
On moderately steep (but still walkable) slopes, like clipped stairs, the controller rapidly bounces between "on ground" and "in air" states. This causes jittery movement and breaks any logic that depends on a stable ground check.

Steps to Reproduce:
I've attached a stripped-down version of my project source code that demonstrates both issues. For Issue 1, you may need to restart the game a few times to trigger it. For issue two, just run the game and try to walk on the taller, steeper slope.

Any insight or help would be greatly appreciated. Happy to provide more details if needed.

Thanks!

mesa - stripped.7z

[Josh]

Thanks for the detailed report, will investigate this...

[Josh]

Some strange things about this:

• It seems to happen only with wedge shapes.
• If one wedge shape fails, they both fail, always.
• A box shape in the same scene never fails.
• The player bounces up and down on large ramps, but a smaller ramp with the same shape has no problems.

Is this consistent with what you have seen? I think the most likely explanation is the Newton physics convex hull class is calculating an erroneous bounding box.

 

[Josh]

Is there anything special about the large wedge? Was it made using the carve tool? I tried creating a new wedge the exact same size, and that one works perfectly. If I step on your wedge, the player bounces up and down and I hear the footstep landing sound, but my own new wedge works fine. 

[Josh]

This will take some more time to figure out...

[vega]

Can confirm that:

- The smaller wedge is fine and does not produce issue 2.

- If issue 1 occurs, both wedges break.

- The wedge was created using the “Create” menu like normal, there shouldn't be anything special about it.

I’m not sure if this only happens with wedges, but i assume so. Will test this in an hour or so when i get on my PC. 

[Josh]

You don't need to do any more testing for now. I found where the problem is, but I don't see why it is happening yet. Will continue work on this tomorrow.