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: Readonly<WritableXYAndZ>, middle: Readonly<WritableXYAndZ>, end: Readonly<WritableXYAndZ>, sweep?: AngleSweep, result?: Arc3d): undefined | Arc3d

@returns elliptical arc, or undefined if construction impossible.

Parameter Type Description
start Readonly<WritableXYAndZ> start of arc, on an axis.
middle Readonly<WritableXYAndZ> point on arc somewhere between start and end.
end Readonly<WritableXYAndZ> 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 - undefined | Arc3d

elliptical arc, or undefined if construction impossible.

Defined in

Last Updated: 24 October, 2025