Module flatten 

Adaptive Bezier curve flattening via De Casteljau subdivision.

Mirrors SplashXPath::addCurve from splash/SplashXPath.cc exactly, including the cx/cy/cNext stack representation and the MAX_CURVE_SPLITS = 1024 hard limit.

Algorithm

The curve is stored as a linked list of pending segments in the CurveData array. Each segment [p1, p2] covers control points cx[p1*3..p1*3+3] and endpoint cx[p2*3]. The loop advances p1 rightward, either emitting a line segment when the chord deviation is within flatness_sq, or splitting via De Casteljau and inserting a midpoint p3.

Output convention

p0 (the curve start) is implicit — it is the caller’s current point and is not included in out. The first point appended to out is the endpoint of the first emitted sub-segment, and the last point appended is always p3 (the curve endpoint).

Structs

CurveData

Stack storage for the De Casteljau subdivision loop.

Functions

flatten_curve

Flatten a cubic Bezier curve into a sequence of line endpoints.