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Object scale seems to be applied twice to Dyntopo Constant Detail
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Description

System Information
Operating system: Windows 10 64-bit
Graphics card: ASUS Strix GTX 1080 Advanced

Blender Version
Broken:
blender-2.80.0-git.a1ae04d15a9f-windows64 (Jan 30)
blender-2.80.0-git.1d908bffddb4-windows64 (Jan 24)

Works in:
blender-2.80.0-git.91a155833e59-windows64 (Jan 8)

Short description of error
I did search for similar bugs, and found some, but all closed. I also found this commit that seems related: https://developer.blender.org/rB22bc6142c3c505de2f2a9a85941c43236f53b941

Object scale seems to be applied twice to Dyntopo Constant Detail. The commit above argues that Constant Detail should be in world space, and maybe that's true, but that is definitely not what it is right now.

Exact steps for others to reproduce the error

  • From the default scene
  • Enable the wireframe overlay
  • Go to sculpt mode
  • Enable Dyntopo, Detailing: Constant Detail and set Resolution to 10
  • Draw on the cube, you get the expected detail level
  • Go to object mode
  • Press S, and type 0.1 to scale the cube down to 1/10 of it's original size
  • Go to Sculpt mode
  • Reenable Dyntopo (Verify it is still set to Constant Detail and Resolution 10)
  • Draw on the cube, the resulting mesh is now 10 times as high (more dense) as before

The only behaviour that seems intuitive to me is if constant detail is relative to a blender unit in the object's scale. If an object is scaled, I expect to be able to continue sculpting on that object with the same constant detail, and expect the same mesh resolution as the sculpting I did before the object was scaled. (This is how it worked in the build from January 8 above.) If I want the detail to be relative to world space, I expect to have to apply scale first.

But in any case, the current behaviour makes no sense.

Details

Type
Bug

Event Timeline

Philipp Oeser (lichtwerk) triaged this task as Confirmed, Medium priority.

Maybe I am misunderstanding what rB22bc6142c3c5 intends to do, but to me it seems wrong, too.

btw. tootip still reads
{SCULPT_DYNTOPO_DETAIL_CONSTANT, "CONSTANT", 0, "Constant Detail", "Mesh detail is constant in object space according to detail size"}

@Brecht Van Lommel (brecht): are we getting it wrong?