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Dynamic Sculpting: Inflate Brush artifacts --- could freeze blender
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Description

--- Operating System, Graphics card ---
Ubuntu 13.04
Graphics Card: ATI RV630 [Radeon HD 3600 Series]



--- Blender version with error, and version that worked ---
It occours in 2.66.6 (version 2.66 (sub 6), revision b'56271'. b'Release')

There is no blender version (with dynamic topology) without this bug.



--- Short description of error ---
( Dynamic Topology activated. )

Artifacts generated during painting with the inflate brush. There is no way to clean up those artifacts within sculpting mode.
If you watch the artifact from the back-side, you will se a blob.

Painting over those artifacts takes some cpu effort. If you are unlucky (using 'dots', this bug could freeze blender.
Using the inflate brush could also ruin hours of work.



--- Steps for others to reproduce the error (preferably based on attached .blend file) ---
1 - Load InflateBrushBug.blend
- Pre-defined Setup in the blend file
+ It will put you into Sculpting mode automatically
+ The actual brush is set automatically to the Inflate brush
+ Stroke is set to airbrush. Strength is set to 1.
2 - Activate Dynamic Sculpting
3 - Draw over the surface with the inflate Brush

If you set stroke method to "dots" or "airbrush", the bug occours faster. It also occours on "space" with lower strength (around 3).
"collapse short edge" does not prevent the bug!

If you like, see this video.
http://www.youtube.com/watch?v=3W5NIrNqEp8&list=PLvTqAnaoAttpxyD2OYAOHWO3nsHDixxJ6



--- If you like to see the bug instantly. ---
I started with a more general plane to show, that this bug is not limited to valleys.
There is a second attachment. (InflateBug-immediate.blend)
Load this file. Do same steps as above. If you paint into the bottom edge of the valley, the bug occours immediately.
I started this Bug Report basing on a plane to show that it affects sculpting in general.

Details

Type
Bug

Event Timeline

This bug occours in traditional sculpt mode (no dynamic topology), too! Sorry. But, it wont freeze Blender!
If Bug occours in traditional sculpt, i could correct the artifacts by painting over the blobs (on its opposite site) with the smooth brush. It is easy and fast.

Trying 'collapse short edge', it prevents blender from freezing, too. Cleaning artifacts is more difficult. Using smooth brush and simplify brush.
Correcting the artifacts, accidents could happen ... I mean, fine shapes of a sculpting could be erased with the simplify brush.
Wouldnt it be more safe to disable dynamic sculpting for the inflate brush?
___
(A small patch. Please check it, am learning.
It should disable dynamic topolology for the inflate brush.
Works on my own blender build.
I hope the attachment will upload if I save changes.)

Confirmed here, on the immediate version I am getting a hang very easily if I scuplt at the central crease.

Note, I don't think deactivating is the correct thing here. this looks like a general issue that should be fixed.

@Antony Riakiotakis (psy-fi), we don't have nicholasbishop active anymore, hope you're fine if i re-assign the report to you :)

Antony Riakiotakis (psy-fi) lowered the priority of this task from Confirmed to Low.Aug 27 2014, 6:07 PM

@Leonard Siebeneicher (siebeneicher), are you actually able to reproduce the issue with current stable release 2.73a and 2.74-RC2 from download.blender.org/release/Blender2.74 ?

Or maybe someone else can reproduce the issue?

It still easy to do. Sculpting on a plane using Inflate brush and Dynatopo from top Ortho view. Blobs appear on the back side of the area that is being worked on.

Poke - browsing old bugs is this still an issue?

yes.

I could trigger same bug on Blender 2.78c. Used perspective view.

Blender hash e92f2352830

See ...

I think it's doing what It's supposed to. You can mangle up the mesh using any brush type if you sculpt a certain way with particular settings.

Try the following settings with dyntopo (I got perfectly clean results with them):

  • Strength: 3
  • Autosmooth: 1
  • Stroke method: Space
  • Spacing: 1%

Maybe the default settings should be changed to these?