API Reference › core-geometry› Curve › Arc3d › CreateStartMiddleEnd

createStartMiddleEnd MethodStatic

Create an elliptical arc from three points on the ellipse: two points on an axis and one in between.

createStartMiddleEnd(start: XYAndZ, middle: XYAndZ, end: XYAndZ, sweep?: AngleSweep, result?: Arc3d): Arc3d | undefined

@returns elliptical arc, or undefined if construction impossible.

Parameter Type Description
start XYAndZ start of arc, on an axis.
middle XYAndZ point on arc somewhere between start and end.
end XYAndZ point on arc directly opposite start.
sweep AngleSweep angular sweep, measured from start in the direction of middle.
For a half-ellipse from start to end passing through middle, pass AngleSweep.createStartEndDegrees(0,180).
Default value is full sweep to create the entire ellipse.
result Arc3d optional preallocated result.

Returns - Arc3d | undefined

elliptical arc, or undefined if construction impossible.

Defined in

Last Updated: 28 April, 2026