A.N.T Landscape Erode function reports error #74604

System Information
Operating system: Win 10
Graphics card: Dual Titan RTX

Blender Version
Broken: 2.82

Short description of error
Clicking "Landscape Eroder" in sidebar creates error

Exact steps for others to reproduce the error
Enable the default A.N.T Landscape Addon that comes with Blender (v0.1.8)
Generate a landscape (N>Create>Landscape>Landscape)
In Landscape tools click "Landscape Eroder". You'll get this error:

//Traceback (most recent call last):
File "C:\Program Files\Blender Foundation\Blender 2.82\2.82\scripts\addons\ant_landscape\ant_functions.py", line 1065, in execute
ob.vertex_groups.active = vg
RuntimeError: Error: RNA_property_pointer_set: expected ID type, not VertexGroup.

location: :-1//

Added subscriber: @AndrewPrice

Added subscriber: @BrendonMurphy

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

hi I'll confirm that it's reporting an error yes. However the erosion tool still appears to work. On first run it erodes the mesh and reports error, the ui still appears and settings can be changed. Each change reports the same error and appear to work.
I will look into the error and try to see it fixed withoout disabling the nice erosion feature.
Fix may take a few weeks.
Thanks.

Thank you for the fast response!

Are you sure it successfully performs the function though? In this video it seems to erode the mesh after the function is complete. Though he's using a modified version of the original addon, so I'm not sure if it's the normal behaviour.

Any updates on this? Hoping to use this in a landscape tutorial.

Added subscriber: @girafic

try to open the file "C:\Program Files\Blender Foundation\Blender 2.82\2.82\scripts\addons\ant_landscape\ant_functions.py", scroll to line 1065 and replace with

ob.vertex_groups.active_index = vg.index

Report then if that worked for you.

Added subscriber: @mano-wii

The solution proposed by @girafic seems reasonable.
I'll wait for confirmation if it worked and then commit

This issue was referenced by blender/blender@10bd3fb4cb

Changed status from 'Confirmed' to: 'Resolved'

Thanks so much! Just tried with the latest build and it seems to work without error now. Beautiful! Cheers

Added subscriber: @renderluz-2

A similar error where the vertex groups for eroding are not being created is present on Blender 3.0 alpha
the mesh do gets eroded, but the vertex groups are not created.

scripts\addons\ant_landscape\ant_functions.py", line 1062, in execute

  ob.vertex_groups.active = vg

RuntimeError: Error: VertexGroup 'capacity' not found in object 'Landscape'

location: :-1

The problem is non existent on 2.93 official, but on the new 3.0 release the eroding vertex weight map creation is broken.

Im going to test the newest build of 3.0

Added subscriber: @billhails

Hi, also hit this bug (version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: blender/blender@f1cca30557) and started digging, the issue seems to be at 1679f2fdbb/ant_landscape/ant_functions.py (L1006) - I added debug to print ob.vertex_groups.keys() before and after assignment and got:

ANT vertex groups before assign ['rainmap', 'scree', 'avalanced', 'water', 'scour', 'deposit', 'flowrate', 'sediment', 'sedimentpct', 'capacity']
ANT vertex groups after assign []

So assigning to ob.data is wiping ob.vertex_groups

confirmed, downloaded 2.93 LTS and added the same debug:

        print('ANT vertex groups before assign', ob.vertex_groups.keys())
        ob.data = me
        print('ANT vertex groups after assign', ob.vertex_groups.keys())

output with 2.93:

ANT vertex groups before assign ['rainmap', 'scree', 'avalanced', 'water', 'scour', 'deposit', 'flowrate', 'sediment', 'sedimentpct', 'capacity']
ANT vertex groups after assign ['rainmap', 'scree', 'avalanced', 'water', 'scour', 'deposit', 'flowrate', 'sediment', 'sedimentpct', 'capacity']

I have a working fix for this (save weights before assign, recreate vertex groups after), the resulting vertex groups are visible in the inspector and weight painting shows they have sensible looking values but is seems a very hacky and memory intensive fix for these large meshes.

Added subscriber: @jorianw

I don't know much about coding, so I don't really understand what that means... Is there any code or solution i can use to fix this problem?

Since you asked, and if you trust me...

Basically the problem is a non-backwards compatible change in the 3.0 blender API means that when you replace an objects mesh with another mesh, the objects vertex groups now all get deleted.
ANT eroder expects them to still be there and crashes attempting to access them.
My fix is to keep a handle on the old vertex groups and copy them back afterwards.

DISCLAIMER Use at your ow risk etc. but it worked for me.
Locate your ant_functions.py in your Blender application files. I'm on a mac so for me that's /Applications/Blender.app/Contents/Resources/3.0/scripts/addons/ant_landscape/ant_functions.py
Make a backup of it just in case.
Replace it with the attached file.
[Re]start blender.

ant_functions.py

Added subscriber: @Cakes

Confirming this worked for me, thanks!

Added subscriber: @Colin_Knu

Is this going to be fixed in main? The issue persists in the 3.0.1 update.

Added subscriber: @KAYOKIIN

I tried your fix on Blender 3.0.1 and it worked! Thank you very much!

When clicking on "Landscape Tool" -> "Landscape Eroder", I get all the vertex groups. I just renamed the existing file with "backup" at the end just in case something wouldn't work, then copy/pasted yours.

For Win 10: C:\Program Files\Blender Foundation\Blender 3.0\3.0\scripts\addons\ant_landscape

Added subscriber: @Mariam-Songhulashvili

This also worked on 3.1 Thank you very much

Added subscriber: @zelebooba

Thanks! blender 3.1

Added subscriber: @sammedia

You guys are the best! Works perfect in 3.1 and even in the Blender Octane Edition!

Added subscriber: @IOOLEE

thanks!This bug still exists in the 3.2alpha

Added subscriber: @DRN

Really thank you. Worked on Blender 3.0

Added subscribers: @bill-1, @dooZaev4

Blender 3.2.0 here, issue still present, and @bill-1 Hails's ant_functions.py file still does the trick.

Added subscriber: @Dyrus95

This mistake still occurs in version 3.2, but the mistake is solved now, love you guys❤

Added subscriber: @palmer13

I have the same problem in 3.2. downloading the file and replacing it fixed it, but it's rather uncomfortable for me to download files and replacing them on my computer...
Is the dev team ever going to address this issue and implement this fix?

Added subscriber: @vindarjuan

同样遇到了问题~解决了！！！This mistake still occurs in version 3.2, but the mistake is solved now, love you guys too~

Added subscriber: @EXELEC

Removed subscriber: @EXELEC

Added subscriber: @juliusINCREON

Blender 3.2 - yes also worked for my. Thank you!
Just a quick comment so the thread is staying active, and the dev team hopefully fixes the bug :)
best regards

Added subscriber: @Yanbobo

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A.N.T Landscape Erode function reports error #74604