pub const MITER_LIMIT: f32 = 4.0;Expand description
The sharpest corner a miter is drawn for, as a multiple of the half-width the miter would reach (ADR-0158).
A corner of interior angle theta needs width / sin(theta / 2), which
grows without bound as the corner sharpens: a spike that doubles back on
itself would reach to infinity and paint a spear across the frame. Past the
limit the joint reverts to the flat half-width — a bevel, which is what
stroke-miterlimit selects in SVG and what an unmitred joint always drew.
It is a fallback and not a truncation: clamping to MITER_LIMIT * width
instead leaves the stroke reaching four half-widths past the vertex along its
own direction, which reads as a burr rather than as a corner.
4.0 is adopted, not measured. It is SVG’s stroke-miterlimit default,
and it draws exactly every corner at or above
2 * asin(1 / 4) = 28.96 degrees — that is the angle at which
1 / sin(theta / 2) reaches 4, so the limit is a statement about which
corners are mitred and which are bevelled, not a tuned number (ADR-0071).
diamond’s 61.9-degree vertex needs 1.9437 and is well inside it; a Maurer
chord web’s near-reversals are the population outside it.