Mesh Repair › Make Delone improves the shape of the triangles in a mesh without moving any vertex. It flips edges between neighboring triangles to reach a Delaunay triangulation (the app spells it "Delone"), which turns long, thin triangles into better-shaped ones. Use it after Simplify or Fill Holes, when the mesh has many needle-like triangles.
When it helps
- After Simplify. Collapsing many edges can leave long, thin triangles.
- After Fill Holes. The Flat option fills a hole with as few triangles as possible, which often gives fans of long, thin triangles across the patch. Select the patch and run Make Delone on it.
- Before smoothing or subdividing, so that these tools start from well-shaped triangles.
What an edge flip does
Two triangles that share an edge form a four-sided shape, and the shared edge is one of its two diagonals. A flip replaces it with the other diagonal. Make Delone keeps the diagonal that gives the better-shaped pair of triangles. This is the Delaunay rule: the circle through the three corners of a triangle should not contain the fourth corner of the pair.
- Vertices do not move, so the number of vertices and triangles stays the same.
- On a flat area the surface does not change at all. On a curved area a flip changes the shape slightly, and Max Angle Change limits how much.
- Because vertices stay in place, Make Delone cannot fix uneven density or badly placed vertices. For that, use Remesh.
Use Make Delone
- Select one mesh in the Scene tree. Make Delone works with exactly one selected mesh.
- Optional: select the part of the surface to process, for example a hole patch. With a selection, only the selected triangles are changed. Selected edges are never flipped.
- Open Mesh Repair › Make Delone.
- Keep the default settings or change them (see below).
- Click Apply. The panel stays open and shows how many edges were flipped. You can click Apply again: when it reports 0 flips, nothing more can be improved with these settings.
To see the triangles before and after, press L.
Settings
| Parameter | What it does | Default |
|---|---|---|
| Iterations | The number of passes over the mesh. In each pass, the tool checks the triangles and flips eligible edges | 5 |
| Max Angle Change | An edge is flipped only if this changes the angle between the two triangles (the dihedral angle) by no more than this value. Lower values protect the shape of curved areas | 30° |
| Reduce Total Angle | 0% optimizes only the Delaunay criterion. 100% only minimizes the angles between neighboring triangles and ignores the Delaunay criterion. Values in between mix both | 0% |
Under Advanced:
| Parameter | What it does | Default |
|---|---|---|
| Intrinsic Delone | Treats every edge as a geodesic line between its end vertices on the original mesh; the viewport still draws edges as straight segments. When it is on, only Iterations remains in the panel | Off |
| Critical Tri Aspect Ratio | Triangles with a larger aspect ratio (a measure of how stretched a triangle is) are treated as degenerate, and Max Angle Change is skipped for them | 1000 |
Result
After Apply, the panel reports the number of flips, for example "31260 edge flips on last apply".
Here is a real case. A mechanical part of 133,194 triangles was simplified to 13,318 triangles with Simplify (Target Triangles, 10%). Make Delone with the default settings then reported 3561 edge flips; a second Apply found 24 more. The triangle count stayed at 13,318, and the number of very stretched triangles (aspect ratio above 10) went down from 2,390 to 2,210. On flat faces the vertices are only on the outlines, so long triangles remain there: Make Delone can choose better diagonals, but it cannot add vertices.
