Add mesh utilities to flip all/some polygons.
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Authored by Bastien Montagne (mont29) on Feb 19 2016, 11:57 PM.

Details

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Maniphest Tasks

T42526: Generated normals can be opposed to face one, needs winding flipping in this case
T47490: STL: faces not normalized correctly when exporting multiple meshes

Commits

rBS877f44162853: BKE_mesh: add polygon flipping tools.
rB877f44162853: BKE_mesh: add polygon flipping tools.

Summary

This allows to easily invert all or some normals of a mesh, outside of BMesh/editing context.
It is useful in several cases, this pacth use it to invert back normals after transforming
a mesh with a negative matrix, and to fix poly normals after setting custom loop normals
opposite to it in normal modifier.

Notes:

Obviously not for 2.77, this patch is not safe enough!
This invalidates tessellation, calling code has to take care of this as needed.
Not sure whether we can optimize CustomData_swap?
Remaed current CustomData_swap to CustomData_swap_corners, since that one does swapping 'internal' to one item, and not swapping between items of the cdata arrays...

Fix T47490: STL: faces not normalized correctly when exporting multiple meshes
Fix T42526: Generated normals can be opposed to face one, needs winding flipping in this case

Diff Detail

Repository: rB Blender

Event Timeline

Bastien Montagne (mont29) updated this revision to Diff 6139.Feb 19 2016, 11:57 PM

Bastien Montagne (mont29) retitled this revision from to Add mesh utilities to flip all/some polygons..

Bastien Montagne (mont29) added a reviewer: Campbell Barton (campbellbarton).

Bastien Montagne (mont29) updated this object.

Bastien Montagne (mont29) added tasks: T47490: STL: faces not normalized correctly when exporting multiple meshes, T42256: Translation operator moves Child-Of constrained bones in the parent space instead of world.

Bastien Montagne (mont29) updated this object.Feb 19 2016, 11:59 PM

Bastien Montagne (mont29) added a task: T42526: Generated normals can be opposed to face one, needs winding flipping in this case.

Bastien Montagne (mont29) removed a task: T42256: Translation operator moves Child-Of constrained bones in the parent space instead of world.

Add flipping utils to mesh and polygon RNA struct.

While good to have, flipping normals shouldn't be automatic.

Importers can exporters can check for this and handle it if they need.

source/blender/blenkernel/intern/mesh.c
1963–1967 ↗	(On Diff #6149)	This is going to happen when you do: `ob.data = mesh`, and assigning this twice will flip the normals. In fact think transforming the normals above is incorrect too.

This revision now requires changes to proceed.Feb 21 2016, 3:34 PM

Some minor adjustements, remove auto-flipping from BKE_mesh_transform.

Bastien Montagne (mont29) marked an inline comment as done.Feb 21 2016, 5:52 PM

Bastien Montagne (mont29) added inline comments.

source/blender/blenkernel/intern/mesh.c
1963–1967 ↗	(On Diff #6149)	Removed that from patch, indeed not convinced we should do that implicitly. Not sure I understand the comment about `ob.data = mesh` though, afaik it does not call BKE_mesh_transform at all?