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IDProjectCategoryView StatusDate SubmittedLast Update
0007538opensim[REGION] Physics Enginespublic2015-04-23 18:002015-08-25 20:42
Reporterkenvc 
Assigned To 
PriorityhighSeveritymajorReproducibilityalways
StatusnewResolutionopen 
PlatformDual quad core Xeon 32 gb ramOSWindows Server 64 bitOS Version2012
Product Versionmaster (dev code) 
Target VersionFixed in Version 
Summary0007538: Bulletsim: If a cut prim or mesh surface is tilted very much in both x and y direction, most physics vehicles fall through it.
DescriptionBulletsim: If a road cut prim or mesh surface is tilted very much in both the x and y direction at the same time, most physics vehicles fall through it.
Steps To Reproduce1. Create a prim shaped like a ramp by using a prism shape and make it large
2. If it is flat then vehicles work on it OK.
3. Rotate it so the bottom side is now on the top
3. If the shape is tilted very much at all in both the x and y directions, physics vehicles will now fall through it.
4. Roads or race tracks that are built observing this rule work fine. Those that don't have fall through issues.
5. This same rule applies to mesh roads. If the mesh surface tilts in multiple directions like this within a short distance a fall or sink through will happen.
Additional InformationHans says it took him a month to figure out why his roads were not working right with Bulletsim. This was why.
TagsNo tags attached.
Git Revision or version numberr/25938
Run Mode Grid (1 Region per Sim)
Physics EngineBulletSim
Script Engine
Environment.NET / Windows64
Mono VersionNone
ViewerNA
Attached Files

- Relationships

-  Notes
(0028084)
kenvc (reporter)
2015-04-25 08:34

I know personally of many others who have had the same fall-through issue with physical cars on bulletsim with tracks made from various shapes.

If all of you who have seen this issue could add a note to this mantis describing what happened and what kind of shape it was that fell through, that would be of significant help for the developer to reproduce the issue and find the cause.
(0028086)
kenvc (reporter)
2015-04-26 06:16

Robert, I just sent you a simple prim prism shape in osg that illustrate this issue in the simplest of terms. The other shape I sent is a more complex prim shape that has the same issue. The issue with the fall through on certain spots on the mesh track seems to be related to the surface being tilted in several different angles within a short distance.

Hopefully this simple prims prism shape will help find the cause of this issue. Let me know if there is anything else you need that might help you with this.
(0028451)
kenvc (reporter)
2015-05-26 11:09

It seems the cut side of the prim is most often the side with the issue. The prim can sometimes be flipped over and the other side will be OK.

Twisting mesh roads for example that have the top surface tilted at many different angles also seem to often have a serious issue of vehicles dropping through them.

Most people who have racing sims have simply given up trying to make cut prim or mesh roads work that have any complex surfaces.
(0028700)
JohnF (reporter)
2015-06-14 07:57

I have discovered the fall through problem with some mesh steps which I had made phantom and placed a prism prim underneath in order to walk on. These worked fine with ODE but I fell through them once we upgraded to Bullet sim. The Prisms were angled. The problem went away once they were orientated along correct x,y axis. I found that cutting a cub to a prism shape and using this instead of the prism worked even on an angle. Also flattening a cube and tilting and angling it seems to work ok as well. Only having the problem with the prism it seems
(0028737)
kenvc (reporter)
2015-06-18 13:17

I have seen the same issue with a cut cube. It seems to depend on which side of the cut you place up as well as the angle.
(0029371)
kenvc (reporter)
2015-08-25 20:42

Here is some very interesting info from a user who did a lot of testing on this subject a few days ago:

"Size matters. Was driving the little go kart around the race track today and noticed that it was falling through slightly in a couple of places, whereas the formula racer didn't. They're using the exact same script, so I wondered what the difference was. Size was the only thing I could think of, so I made the go kart ? its original size and drove it around. Looked funny ... and drove awful! Fell through all over the place, even had trouble on plain terrain -- it was un-drivable. Then I made its root prim bigger than original, and it became as good as the formula racer.

I don't know the technical reasons for all this, but it does sort of intuitively make sense. Not sure if it suggests a solution, but it's at least a data point."

- Issue History
Date Modified Username Field Change
2015-04-23 18:00 kenvc New Issue
2015-04-23 18:02 kenvc Summary Bulletsim: If a road prim or mesh surface is tilted in both the x and y direction, most physics vehicles fall through it. => Bulletsim: If a road prim or mesh surface is tilted very much in both x and y direction, most physics vehicles fall through it.
2015-04-25 07:48 kenvc Steps to Reproduce Updated View Revisions
2015-04-25 07:51 kenvc Summary Bulletsim: If a road prim or mesh surface is tilted very much in both x and y direction, most physics vehicles fall through it. => Bulletsim: If a cut prim or mesh surface is tilted very much in both x and y direction, most physics vehicles fall through it.
2015-04-25 07:51 kenvc Description Updated View Revisions
2015-04-25 07:52 kenvc Description Updated View Revisions
2015-04-25 08:34 kenvc Note Added: 0028084
2015-04-26 06:16 kenvc Note Added: 0028086
2015-05-26 11:09 kenvc Note Added: 0028451
2015-06-14 07:57 JohnF Note Added: 0028700
2015-06-18 13:17 kenvc Note Added: 0028737
2015-08-25 20:42 kenvc Note Added: 0029371


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