Complexity
The surfaces in a STEP or IGES file are exact, so drawing them requires converting each one into triangles. The complexity level sets how closely those triangles follow the true surface. A higher level draws curves more smoothly and takes longer to load.
The levels
Each level sets two limits. The first is the furthest a triangle may lie from the true surface, measured as a fraction of the diagonal of the whole model's bounding box. The second is the largest angle allowed between neighbouring triangles on a curved surface.
| Level | Distance from the surface | Angle between triangles |
|---|---|---|
| Low | 0.5% of the diagonal | 28.65° |
| Medium | 0.1% of the diagonal | 20° |
| High | 0.03% of the diagonal | 12° |
| Very High | 0.01% of the diagonal | 6° |
The Info tab's Complexity section shows the current Level and, under Tolerance, the two limits it produces for this file, with the distance in the file's own unit.
Auto
A file always opens at Auto, which chooses a level from the number of triangles the model would draw. It converts the model at Medium first. If the result exceeds 2 million triangles, it uses Low instead, and if it is under 400,000 triangles, it uses High. Auto never chooses Very High. The limits are fixed numbers, so a given file opens at the same level on every Mac.
The Level picker offers the four fixed levels and shows the one Auto chose. There is no setting for a different starting level.
Choosing a level
Selecting a level in the Level picker reads the file again at that level. The loading overlay reports progress while it runs, and the camera keeps its position.
A level chosen by hand is checked against a triangle budget derived from this Mac's graphics memory, between 2 million and 30 million triangles. When the chosen level would exceed it, Solidly uses the highest level that fits, and the Info tab's Notes section names both levels and the budget.
Low is the lowest level, and a very large assembly can still exceed 2 million triangles at Low.
Counts that depend on the level
Triangle and vertex counts describe Solidly's conversion of the surfaces, and they change with the level. For that reason the Info tab's Summary reports parts, placements, and solids for these formats, and no vertex or index counts. Volume and surface area are calculated from the exact geometry, so they do not change with the level.
The command line renderer also opens STEP and IGES files at Auto.