dorianprill / stroke Goto Github PK

This is very useful for font rendering (generating signed distance field)

Thanks

Goal

arclen() is currently implemented using linear approximation, which is fast and simple but not very accurate. Add an alternative method that uses a more advanced technique like legendre-gauss while keeping computational complexity reasonable, or at least configurable.

Problem

Various approaches exist, some established, some more recent. All have certain trade-offs. Raph Levien provides a very insightful analysis in his blog

Solution

Define a useful set of default parameters and/or make them configurable without complicating the API too much.
Implement on of the methods discussed by Raph and rename the current linear implementation to something like arclen_fast() or arclen_linear()

Goal

Implement bounding_box() method for the generic Bezier and BSpline curve types.

Problem

Computing the bounding box requires finding the extrema of a polynomial/curve of degree N, which translates to finding roots of a spline curve of degree N-1. For higher order curves (d > 4) this requires implementing the newton-raphson root finding algorithm.
This may be difficult to do generically for both curve types in a const generic setting because some instability around the Fn-family traits.

It is already implemented with tinyvec::ArrayVec for the specialized types QuadraticBezier and Cubic Bezier where N is fixed.