editor / turnAbout

Function: turnAbout()

turnAbout(point, center, direction): Point

Defined in: geometry/turn-about.ts:17

Point turned about a center by the angle of a direction.

Formula: c + R(p − c), R(x, y) = (x cos α − y sin α, x sin α + y cos α): SVG's rotate(α, cx, cy), translate, rotate, translate back. In the SVG frame (y down) a positive angle is clockwise on screen.

Parameters

point

Point

any point of the plane

center

Point

the point that stays where it is

direction

Vector

(cos α, sin α) of the angle (turnDirection)

Returns

Point

the turned point

Kind

geometry

See

REF-SVG11-TRANSFORM