Surface deform modifier says that convex polygons are concave in 0.01 unit scale scene
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Description

System Information
Win 8, GTX1070

Blender Version
Broken: 2.79 3f614cd (probably others too)

Short description of error

Surface deform modifier says that convex polygons are concave in 0.01 unit scale scene. See image:


None of the angles are above 180 degrees which I thought was the definition of a concave face. Still, the modifier says that the target contains concave polygons. Note that this only happens in a 0.01 unit scale scene (custom scene scale is for Unreal Engine 4 compatibility).

I guess this means some mesh checking functions don't work in custom unit scale scenes which doesn't seem great.

Exact steps for others to reproduce the error

  1. Set unit scale to 0.01 metric.
  2. Create a plane. Rotate it and add a few subdivisions.
  3. Scale the top vertices out a bit.
  4. Create a cube. Add a surface deform modifier.
  5. Target the plane and bind. You get an error saying that the target contains concave polygons. (attached .blend file ends here)
  6. Set unit scale to 1 metric.
  7. Set the 3d cursor to the origin of the scene, set the pivot point to 3d cursor and scale down everything 100 times. Apply scale.
  8. Try binding the surface deform modifier again. Now it works.

Details

Type
Bug