🚀 go-pugleaf

Jacob.Hartog@f99.n121.z1.fidonet.org (Jacob Hartog) writes:

> Assuming you have a coordinate plane with its origin at a given point.
> Does anyone have any idea how you would get the x,y of points on that
> in terms of another coordinate plane skewed off the original one n
> number of degrees with its origin at a different point.

Assuming that all info is stored in a global coordinate system (x,y),
and that the player defines some local coordinate system whose origin is
located at (xc,yc) in the global coord sys, and is furthermore rotated
theta degrees with respect to it, then a point (xl,yl) in the local
coordinate system translates back to a point (x,y) in the global
coordinate system by

    x = xl cos theta - yl sin theta + xc
    y = yl cos theta + xl sin theta + yc

This stuff is taught in any introductory computer graphics class.

Eric Wang
wang@cs.uiuc.edu