Massive interface latency with Texture Paint at small scales w/out culling in 2.73

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This is a brand new issue as of 2.73.

I was working on a 3d print, so my model was only 10cm high, with a scale factor of 1.

While most of the model was paintable without issue, the hands constituted a region of high vertex density- especially considering the subdivision modifier with a preview value of 2. Whenever I turn off culling and try to paint the hands (the character has fingerless gloves) there is an interface latency of 20 seconds to 1 minute before blender is able to do anything else, and the region meant to be painted is left untouched. In addition, there are diagonal streaks through the UV map.

The model works fine when scaled up to 10m. I’d just deal with this and scale before every export, but curiously, there is no problem in 2.72b. Since I have yet to notice any notable difference between 2.73a and 2.72b, I’m just going to switch back for now, but I felt I’d bring this problem to everyone’s attention so that a proper bug report could be filed.

To reproduce:

  • Set Blender to metric units.
  • Produce a cube. Scale the cube to dimensions smaller than 1cmx1cmx1cm. A smaller object will produce a proportionally larger effect. Also, you will probably have to adjust your camera clipping options to get it into frame.
  • Use smart unwrap to UV map the cube, make an image for the UV map, make appropriate materials and textures.
  • Apply a subdiv modifier to the cube. On my computer, with a 1cm[SUP]3[/SUP] cube, a value of 2 on a simple cube is insufficient to trigger the problem, but 3 produces notable latency and 4 makes texture painting nearly unusable.
  • In texture painting mode, disable the options; occlude, cull, normal
  • Attempt to paint the cube.

In 2.73, that series of operations leads to complete inoperability of texture painting, but in 2.72 it’s fine.

I’ve attached a file containing the hand from my model. It’s been a bit mangled and splayed so that I could verify the geometry was acceptable (and to check if overlapping volumes were problematic, but the problem still persists.

hand texture problem.blend (507 KB)

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