Triangle mesh BGE character mode crash #40684

New Issue

Joseph Masaki · 2014-06-18T03:10:22+02:00

Joseph Masaki commented

2014-06-18 03:10:22 +02:00

System Information
MS Windows 7 Home Premium 64-bit SP1
NVIDIA GeForce GT 555M

Blender Version

Broken: 2.71 Release Candidate 2 a19c1be

Although it's been broken since at least 2.67.1 r57348

Short description of error
When object's collision bounds is set to triangle mesh and physics mode is set to character, blender will crash when object hits another.

Exact steps for others to reproduce the error
Change object collision bounds to triangle mesh
Start game engine

local_add_move_bug.blend
(File is from another bug)

**System Information** MS Windows 7 Home Premium 64-bit SP1 NVIDIA GeForce GT 555M **Blender Version** Broken: 2.71 Release Candidate 2 a19c1be Although it's been broken since at least 2.67.1 r57348 **Short description of error** When object's collision bounds is set to triangle mesh and physics mode is set to character, blender will crash when object hits another. **Exact steps for others to reproduce the error** Change object collision bounds to triangle mesh Start game engine [local_add_move_bug.blend](https://archive.blender.org/developer/F94600/local_add_move_bug.blend) (File is from another bug)

Joseph Masaki commented

2014-06-18 03:10:22 +02:00

Changed status to: 'Open'

Joseph Masaki commented

2014-06-18 03:10:22 +02:00

Added subscriber: @JosephMasaki

blender-admin commented

2014-06-18 03:10:22 +02:00

#42084 was marked as duplicate of this issue

blender-admin commented

2014-06-18 03:10:22 +02:00

#42363 was marked as duplicate of this issue

blender-admin commented

2014-06-18 03:10:22 +02:00

#33151 was marked as duplicate of this issue

Inês Almeida commented

2014-06-18 10:31:54 +02:00

Added subscriber: @brita

Antonis Ryakiotakis commented

2014-06-19 22:11:37 +02:00

Added subscriber: @Psy-Fi

Antonis Ryakiotakis commented

2014-06-19 22:11:37 +02:00

This is really the weirdest thing...the localGetSupportingVertexWithoutMargin should be defined for the triangleshape type that the offending variable is. I even have -fsanitize-address on and I haven't seen any error here.

However, a lead for you Ines might be that changing the physics type of the object from character to rigid body seems to bypass the problem. So maybe there's some initialization that is skipped here.

I suspect this might not be a blender bug, but you can see what happens differently between the two cases so you might at least somehow bypass this. I hope that helps even if a little.

This is really the weirdest thing...the localGetSupportingVertexWithoutMargin should be defined for the triangleshape type that the offending variable is. I even have -fsanitize-address on and I haven't seen any error here. However, a lead for you Ines might be that changing the physics type of the object from character to rigid body seems to bypass the problem. So maybe there's some initialization that is skipped here. I suspect this might not be a blender bug, but you can see what happens differently between the two cases so you might at least somehow bypass this. I hope that helps even if a little.

Antonis Ryakiotakis commented

2014-06-19 22:12:49 +02:00

To avoid any misunderstanding - I haven't seen any error -before- the crash. I can confirm the crash too (This is on Ubuntu 64 bit)

Sergej Reich commented

2014-06-21 11:27:16 +02:00

Added subscriber: @sreich

Sergej Reich commented

2014-06-21 11:27:16 +02:00

From a quick glance, the character controller needs a convex shape. This is either the main shape assigned, or a separate convex shape.
For the latter m_useGhostObjectSweepTest needs to be set to false.

At least one part of the bug is that we are casting the collision shape to a btConvexShape* in CcdPhysicsController::CreateCharacterController().

I'm not sure in what case you'd use a triangle mesh for characer controllers, maybe the best (and easiest) solution would be to disallow that completely.

As for adding a trimesh case in localGetSupportingVertexWithoutMargin(), that doesn't really make sense, for a convex shape ;)

From a quick glance, the character controller needs a convex shape. This is either the main shape assigned, or a separate convex shape. For the latter m_useGhostObjectSweepTest needs to be set to false. At least one part of the bug is that we are casting the collision shape to a btConvexShape* in CcdPhysicsController::CreateCharacterController(). I'm not sure in what case you'd use a triangle mesh for characer controllers, maybe the best (and easiest) solution would be to disallow that completely. As for adding a trimesh case in localGetSupportingVertexWithoutMargin(), that doesn't really make sense, for a convex shape ;)

Inês Almeida commented

2014-06-22 14:16:35 +02:00

@sreich what to you suggest instead of casting the collision shape to a btConvexShape* ? both CcdPhysicsController::CreateCharacterController() and btKinematicCharacterController::btKinematicCharacterController that it is inheriting from receive a btConvexShape . Is that correct? Is this a problem even if we disallow triangle meshes?

Sergej Reich commented

2014-06-22 14:55:10 +02:00

@brita the problem with the cast is that the shape can be non-convex, as a trimesh is. So we have to at least make sure that the shape is in fact convex before casting.

Daniel Stokes commented

2014-07-25 07:34:17 +02:00

Added subscribers: @hg1, @particleemitter, @AngusHollands-4, @kupoman

Daniel Stokes commented

2014-07-25 07:34:17 +02:00

◀ Merged tasks: #33151.

Mitchell Stokes commented

2015-01-08 04:48:51 +01:00

Added subscribers: @sybrenstuvel, @JorgeBernalMartinez

Pierluigi Grassi commented

2015-01-18 13:09:10 +01:00

Added subscriber: @pgi

Pierluigi Grassi commented

2015-01-18 13:09:10 +01:00

If character is not supposed to have a triangle mesh shape, what about a fallback strategy, like the one used for character motion. Print a statement like that one:

"Character motion enabled on non-character object (Cube), falling back to simple motion."

and use the default shape. It can also be used as temporary patch.

If character is not supposed to have a triangle mesh shape, what about a fallback strategy, like the one used for character motion. Print a statement like that one: "Character motion enabled on non-character object (Cube), falling back to simple motion." and use the default shape. It can also be used as temporary patch.

Inês Almeida commented

2015-01-19 11:36:02 +01:00

I think I couldn't really guess what would be the best shape fallback. The user should set it, I think. @sreich thoughts on this?

The idea is that on new files, users won't even have the option. On files that already have this combination it would be left untouched. I am unsure whether most users actually see the prints, so I think there would be cases where the option would be silently changed without the user noticing.

I think I couldn't really guess what would be the best shape fallback. The user should set it, I think. @sreich thoughts on this? The idea is that on new files, users won't even have the option. On files that already have this combination it would be left untouched. I am unsure whether most users actually see the prints, so I think there would be cases where the option would be silently changed without the user noticing.

Jorge Bernal commented

2015-02-17 09:18:32 +01:00

Added subscriber: @TimCrellin

Inês Almeida commented

2015-02-19 12:29:33 +01:00

Changed status from 'Open' to: 'Resolved'

Inês Almeida closed this issue

2015-02-19 12:29:33 +01:00

Inês Almeida self-assigned this 2015-02-19 12:29:33 +01:00

Inês Almeida commented

2015-02-19 12:29:33 +01:00

Closed with D984

Closed with [D984](https://archive.blender.org/developer/D984)

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Triangle mesh BGE character mode crash #40684