Crash in nvoglv64.dll entering edit mode on curve #94454

Closed
opened 2021-12-29 01:51:31 +01:00 by eldee smith · 16 comments

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.39

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-12-26 20:08, hash: 20b438d523
Worked: 2.93 LTS

Caused by eb0eb54d96

Blender crashes with an access violation in nvoglv64.dll when entering edit mode on a curve with the following script running. This worked fine in Blender 2.93 et al, so something has changed with object.to_mesh() that nvoglv64.dll does not like.
See the attached blend file, and run the embedded minimum repro crash_script text file- which is a simple GL handler that should use blf to display the number of mesh polygons in a curve.

# Blender 3.1.0, Commit date: 2021-12-26 20:08, Hash 20b438d523c9
bpy.ops.object.editmode_toggle()  # Operator

# backtrace
Exception Record:

ExceptionCode         : EXCEPTION_ACCESS_VIOLATION
Exception Address     : 0x00007FF9798BBDD0
Exception Module      : nvoglv64.dll
Exception Flags       : 0x00000000
Exception Parameters  : 0x2
	Parameters[0] : 0x0000000000000000
	Parameters[1] : 0x0000000000000000


Stack trace:
nvoglv64.dll        :0x00007FF9798BBDD0  Symbols not available

# Python backtrace

the repro script, for posterity:

import bpy, blf

def draw_test():
    ui_scale = bpy.context.preferences.system.ui_scale
    blf.color(0, 1,1,0,1)
    blf.size(0, int(12 * ui_scale), 72)

    blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(200 * ui_scale), 0)
    blf.draw(0, f"With the curve selected, enter edit mode.")

    blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(220 * ui_scale), 0)
    blf.draw(0, f"If it doesn't crash immediately, try selecting a few points.")

    if bpy.context.mode != 'EDIT_CURVE':
        return

    obj = bpy.context.active_object
    value = 0
    if obj is not None and obj.type == 'CURVE':
        # NOTE: crash is caused by this:
        me = obj.to_mesh()
        value = len(me.polygons)
        obj.to_mesh_clear()
    
    blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(240 * ui_scale), 0)
    blf.draw(0, f"We'll never get to this point, but the curve has {value} polygons.")

handler = None
def register():
    global handler
    handler = bpy.types.SpaceView3D.draw_handler_add(draw_test, (), 'WINDOW', 'POST_PIXEL')
    
def unregister():
    global handler
    if handler is not None:
        bpy.types.SpaceView3D.draw_handler_remove(handler, 'WINDOW')
        handler = None
    
if __name__ == "__main__":
    register()

edit: apparently the blend file did not attach, here it is again
crash.blend

You can get around it passing the evaluated object to to_mesh, see:
crash_corrected.blend

**System Information** Operating system: Windows-10-10.0.19043-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.39 **Blender Version** Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-12-26 20:08, hash: `20b438d523` Worked: 2.93 LTS Caused by eb0eb54d96 Blender crashes with an access violation in nvoglv64.dll when entering edit mode on a curve with the following script running. This worked fine in Blender 2.93 et al, so something has changed with object.to_mesh() that nvoglv64.dll does not like. See the attached blend file, and run the embedded minimum repro `crash_script` text file- which is a simple GL handler that should use blf to display the number of mesh polygons in a curve. ``` # Blender 3.1.0, Commit date: 2021-12-26 20:08, Hash 20b438d523c9 bpy.ops.object.editmode_toggle() # Operator # backtrace Exception Record: ExceptionCode : EXCEPTION_ACCESS_VIOLATION Exception Address : 0x00007FF9798BBDD0 Exception Module : nvoglv64.dll Exception Flags : 0x00000000 Exception Parameters : 0x2 Parameters[0] : 0x0000000000000000 Parameters[1] : 0x0000000000000000 Stack trace: nvoglv64.dll :0x00007FF9798BBDD0 Symbols not available # Python backtrace ``` the repro script, for posterity: ``` import bpy, blf def draw_test(): ui_scale = bpy.context.preferences.system.ui_scale blf.color(0, 1,1,0,1) blf.size(0, int(12 * ui_scale), 72) blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(200 * ui_scale), 0) blf.draw(0, f"With the curve selected, enter edit mode.") blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(220 * ui_scale), 0) blf.draw(0, f"If it doesn't crash immediately, try selecting a few points.") if bpy.context.mode != 'EDIT_CURVE': return obj = bpy.context.active_object value = 0 if obj is not None and obj.type == 'CURVE': # NOTE: crash is caused by this: me = obj.to_mesh() value = len(me.polygons) obj.to_mesh_clear() blf.position(0, int(20 * ui_scale), int(bpy.context.region.height) - int(240 * ui_scale), 0) blf.draw(0, f"We'll never get to this point, but the curve has {value} polygons.") handler = None def register(): global handler handler = bpy.types.SpaceView3D.draw_handler_add(draw_test, (), 'WINDOW', 'POST_PIXEL') def unregister(): global handler if handler is not None: bpy.types.SpaceView3D.draw_handler_remove(handler, 'WINDOW') handler = None if __name__ == "__main__": register() ``` edit: apparently the blend file did not attach, here it is again [crash.blend](https://archive.blender.org/developer/F12780026/crash.blend) You can get around it passing the evaluated object to `to_mesh`, see: [crash_corrected.blend](https://archive.blender.org/developer/F12780484/crash_corrected.blend)
Author

Added subscriber: @testure

Added subscriber: @testure

Added subscriber: @schampions

Added subscriber: @schampions

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*This comment was removed by @schampions*

Added subscriber: @ThomasDinges

Added subscriber: @ThomasDinges
Member

Added subscriber: @lichtwerk

Added subscriber: @lichtwerk
Member

Changed status from 'Needs Triage' to: 'Confirmed'

Changed status from 'Needs Triage' to: 'Confirmed'
Member

Can confirm, will check

Can confirm, will check
Member

Added subscriber: @HooglyBoogly

Added subscriber: @HooglyBoogly
Member

Caused by eb0eb54d96

You can get around it passing the evaluated object to to_mesh, see:
crash_corrected.blend

It is not totally obvious for me why this crashes (passing the non-evaluated curve) and the commit message would imply this is not generally a problem:

If the object isn't evaluated, it uses a temporary copy of the object
with modifiers removed to create the mesh in the same way.

So, I would still like @HooglyBoogly to take a look (it is just not nice to have working [in 2.93] scripts resulting in a crash all of a sudden without explanation somewhere -- even if 3.0 is a compatibility breaking release)
It is also not mentioned in [if it would be an expected breaking change] https://wiki.blender.org/wiki/Reference/Release_Notes/3.0/Python_API

Caused by eb0eb54d96 You can get around it passing the evaluated object to `to_mesh`, see: [crash_corrected.blend](https://archive.blender.org/developer/F12780484/crash_corrected.blend) It is not totally obvious for me why this crashes (passing the non-evaluated curve) and the commit message would imply this is not generally a problem: > If the object isn't evaluated, it uses a temporary copy of the object > with modifiers removed to create the mesh in the same way. So, I would still like @HooglyBoogly to take a look (it is just not nice to have working [in 2.93] scripts resulting in a crash all of a sudden without explanation somewhere -- even if 3.0 is a compatibility breaking release) It is also not mentioned in [if it would be an expected breaking change] https://wiki.blender.org/wiki/Reference/Release_Notes/3.0/Python_API
Member

Unfortunately I can't reproduce this at the moment:
{F12780516 size=full}
Maybe I'm missing something?

Unfortunately I can't reproduce this at the moment: {[F12780516](https://archive.blender.org/developer/F12780516/image.png) size=full} Maybe I'm missing something?
Member

In #94454#1279834, @HooglyBoogly wrote:
Unfortunately I can't reproduce this at the moment:
Maybe I'm missing something?

Is this crash.blend? or crash_corrected.blend?
Are you mouse-selecting points in editmode?
Have you done extrusion prior?

> In #94454#1279834, @HooglyBoogly wrote: > Unfortunately I can't reproduce this at the moment: > Maybe I'm missing something? Is this `crash.blend`? or `crash_corrected.blend`? Are you mouse-selecting points in editmode? Have you done extrusion prior?
Member

Oops! Apparently I was using crash_corrected.blend. I can reproduce it now. I'll look into this.

Oops! Apparently I was using `crash_corrected.blend`. I can reproduce it now. I'll look into this.
Hans Goudey self-assigned this 2021-12-29 23:44:46 +01:00
Member

I've found the fix, it was a relatively simple mistake in eb0eb54d96. However, based on the code there I would strongly recommend you use @lichtwerk's corrected version that uses a depsgraph to get the actual evaluated mesh (or a copy of it anyway).

I've found the fix, it was a relatively simple mistake in eb0eb54d96. However, based on the code there I would strongly recommend you use @lichtwerk's corrected version that uses a depsgraph to get the actual evaluated mesh (or a copy of it anyway).

This issue was referenced by 50c39ff8fe

This issue was referenced by 50c39ff8fe041153bda41657a694e0b154b8cd65

This issue was referenced by c0fdf16561

This issue was referenced by c0fdf16561034f85aadae8a513db16144609b821
Member

Changed status from 'Confirmed' to: 'Resolved'

Changed status from 'Confirmed' to: 'Resolved'
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Reference: blender/blender#94454
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