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Rendering and Hit Testing

After solving, Spline.Render() converts each logical segment into a sequence of path commands stored in BezierPath.

Path generation

For each segment, the renderer:

  1. computes the local chord direction
  2. converts solved tangent angles into segment-local th0 and th1 values
  3. requests control geometry from MyCurve
  4. transforms local control points back into world coordinates
  5. appends cubic Bezier commands to the output path

RenderSvg() is a convenience wrapper that serializes the final path to SVG path data.

Segment marks

BezierPath.Mark(int) stores the logical segment index before subsequent path commands. This is used by the sample application to map a hit-tested path point back to the originating spline span.

Hit testing

BezierPath.HitTest() performs approximate nearest-distance queries against the path.

  • lines are checked analytically
  • curves are subdivided into line segments
  • the best distance and the best marked segment index are tracked

This is sufficient for editing behaviors such as inserting knots, measuring fit error, and refining traced input in DemoSpline.