better low poly

[Alessandro Padovani]

1.7.4.2089

In the last few days I was interested in polygons reduction and gave a look at the various methods available in blender. I also see they're available in the addon advanced section.

planar dissolve (faithful low-poly). The first method is based on planar dissolve. This works with any mesh and maintains uvs, but generates n-gons possibly with a large number of edges, which don't work fine with mesh deformation and subdivision. Thus this is not good for figures, though it's good enough for hard surfaces in props and scenes.

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un-subdivide (quick low-poly). The second method is based on un-subdivision, this only works with quad meshes and generates tris and quads. Thus this is good for figures, but doesn't maintain uvs.

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un-subdivide uv islands. Now I came up with a simple procedure to use un-subdivision and keep uvs. This is good for figures without losing textures and materials. The idea is simple, we keep the uv seams and only un-subdivide inside the uv islands, then merge tris to quads to cleanup the uv seams.

steps:

1. edit mode, select all
2. uv > seams from islands
3. select seams, expand selection, invert selection
4. edge > un-subdivide
5. select all, face > tris to quads 180 with compare seam

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[Thomas Larsson]

Fantastic! Much better than the old lowpoly tools in every respect. Implemented in last commit.

[Alessandro Padovani]

Thank you for the fast fix. Commit 6ea8749 works fine enough, but a couple notes.

1. faithful low-poly. I see you removed the old methods. As explained above un-subdivide only works for quad meshes, so you may want to keep faithful low-poly for scenes and props which may use non-quad meshes. It is also true that we can use the blender tool directly, if this is why you removed the option.
2. tris to quads. The triangles on the seams are not cleaned up, I suspect you didn’t select all before converting tris to quads in point 5, or may be you didn’t set a 180 angle.

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[Thomas Larsson]

Tris to quads, yes, I missed to set the face threshold.

The faithful lowpoly was written from scratch in python and never worked well. I never really used it and am happy to see it go. The quick lowpoly is covered by the present tool if Keep UV Islands and Quads are disabled.

[Alessandro Padovani]

1.7.4.2093, commit 72c89b5.

Still has tris in the seams, if I select all then convert tris to quads they cleanup so I suspect you don’t select all in point 5.

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[Alessandro Padovani]

update. solution. I had a look at the code, you have to set 180 both for the face and shape thresholds, at line 903.

bpy.ops.mesh.tris_convert_to_quads(face_threshold=180*D, shape_threshold=180*D, seam=True)

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[Thomas Larsson]

Fixed in last commit. I also toggle out of edit mode and back in again before converting to quads, because otherwise there is an ugly artifact at the seam on the thigh.

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[Alessandro Padovani]

Commit b497843 works fine, thank you.