Game engine crash with Arraymod + cap-object #38913

New Issue

Karja Krähwald · 2014-03-02T00:30:46+01:00

Karja Krähwald commented

2014-03-02 00:30:46 +01:00

System Information
Windows 7 64, HD 5770

Blender Version
Broken: 2.69 release & hash: 4789793

Short description of error
Game engine cant handle Array modifier cap objects (start or end cap).

Exact steps for others to reproduce the error
GE_Arraycaps.blend Press P

Steps:

add any mesh object
give it an array-modifier
add another mesh object
select this new mesh as cap in the array modifier
press P to start the game engine

I get a crash with this setup.

**System Information** Windows 7 64, HD 5770 **Blender Version** Broken: 2.69 release & hash: 4789793 **Short description of error** Game engine cant handle Array modifier cap objects (start or end cap). **Exact steps for others to reproduce the error** [GE_Arraycaps.blend](https://archive.blender.org/developer/F79440/GE_Arraycaps.blend) Press P Steps: - add any mesh object - give it an array-modifier - add another mesh object - select this new mesh as cap in the array modifier - press P to start the game engine I get a crash with this setup.

Karja Krähwald commented

2014-03-02 00:30:46 +01:00

Changed status to: 'Open'

Karja Krähwald commented

2014-03-02 00:30:46 +01:00

Added subscriber: @karja

Joel Godin commented

2014-03-02 03:03:46 +01:00

Added subscriber: @joel.godin

Joel Godin commented

2014-03-02 03:03:46 +01:00

Can confirm it on Mac OSX 10.9.2

Crash log attached.Crash.txt

Can confirm it on Mac OSX 10.9.2 Crash log attached.[Crash.txt](https://archive.blender.org/developer/F79449/Crash.txt)

Thomas Dinges commented

2014-03-02 14:04:46 +01:00

Added subscriber: @ThomasDinges

Thomas Dinges commented

2014-03-02 14:04:46 +01:00

Crash confirmed on Windows x64.

Patrice Bertrand commented

2014-03-08 22:23:00 +01:00

Added subscriber: @PatriceBertrand

Patrice Bertrand commented

2014-03-08 22:23:00 +01:00

Hello,
I gave it a try, and have pinpointed the bug, but only partially solved. Tried to upload the patch, but ended up with a new Task. Sorry, I don't master the process. See comments associated with task #39056. I copy hereunder:

Crash is in CcdPhysicsController.cpp:UpdateMesh
In 4 places in this module array caps cause RAS_Polygon *poly to be incorrect.
This patch fixes the crash by skipping in such cases,
but the result is that caps are not accounted for in collisions.
So some more work is probably needed.

It seems there is a correspondance of faces after modifier applied to original faces of object. But in the case of caps, the original face does not belong to the object, it belongs to another object. I think it may be the only case where a modifier takes bits of another object. In the correspondance, the faces that have been generated from the caps have a corresponding original face of -1. In the code, this translates to:
RAS_Polygon* poly= meshobj->GetPolygon(origi);
with origi being -1.
GetPolygon() simply does return m_Polygons[num]which results inm_Polygons[-1]`, giving an incorrect pointer, which later crashes.

So it may be that fixing this correctly would imply deeper changes to derived mesh handling, beyond my capacity.
Hope someone more proficient can take it from there.

Hello, I gave it a try, and have pinpointed the bug, but only partially solved. Tried to upload the patch, but ended up with a new Task. Sorry, I don't master the process. See comments associated with task #39056. I copy hereunder: Crash is in `CcdPhysicsController.cpp:UpdateMesh` In 4 places in this module array caps cause RAS_Polygon *poly to be incorrect. This patch fixes the crash by skipping in such cases, but the result is that caps are not accounted for in collisions. So some more work is probably needed. It seems there is a correspondance of faces after modifier applied to original faces of object. But in the case of caps, the original face does not belong to the object, it belongs to another object. I think it may be the only case where a modifier takes bits of another object. In the correspondance, the faces that have been generated from the caps have a corresponding original face of -1. In the code, this translates to: `RAS_Polygon* poly= meshobj->GetPolygon(origi);` with origi being -1. GetPolygon() simply does ` `return m_Polygons[num]` which results in `m_Polygons[-1]`, giving an incorrect pointer, which later crashes. So it may be that fixing this correctly would imply deeper changes to derived mesh handling, beyond my capacity. Hope someone more proficient can take it from there.

Alexey commented

2014-08-10 16:02:14 +02:00

Added subscriber: @Inwader77