Sliding on a box

With boundary="slide" (a fitted OnSurface per face, a fitted OnCurve per edge) a boundary vertex moves within the boundary as meshed: on its face plane, along its edge line, or not at all at a corner.

Minimum scaled Jacobian (higher is better)

Key points

• Face vertices stay on their planes (largest distance 7.8e-16, round-off) and edge vertices on their lines (0); the 8 corners do not move (0).

• Sliding lets the boundary spacing even out: minimum scaled Jacobian 1.00 against 0.30 with the boundary frozen.

• The constraints come from the mesh: with no target passed, resolve found 6 planar patches, 12 edge lines and 8 frozen corners.

• A box is the easy case: every hex can become a cube, so sliding reaches a perfect grid.

The numbers

Distances are each boundary vertex’s distance to its input face plane or edge line; corner move is the largest corner displacement.

boundary	inverted	min SJ	mean SJ	worst 5 % SJ	face off-plane	edge off-line	corner move
input	0	0.0887	0.6640	0.3174	—	—	—
frozen	0	0.3008	0.8737	0.6208	0	0	0
slide	0	1.0000	1.0000	1.0000	7.8e-16	0	0

Bold: the best value in each column among the results (highest scaled Jacobian; lowest count, objective, time, change or distance); the input row is for reference.

Run python examples/smoother/hex/02_slide_box.py to reproduce; it prints these numbers.