Rotate a Geometric Structure
Rotate a geometric structure by an angle theta around a centerpoint xy.
Rotate(x, y = NULL, mx = NULL, my = NULL, theta = pi/3, asp = 1)
x, y |
vectors containing the coordinates of the vertices of the polygon
, which has to be rotated. The coordinates can be passed in a plotting structure (a list with x and y components), a two-column matrix, .... See |
mx, my |
xy-coordinates of the center of the rotation. If left to NULL, the centroid of the structure will be used. |
theta |
angle of the rotation |
asp |
the aspect ratio for the rotation. Helpful for rotate structures along an ellipse. |
The function invisibly returns a list of the coordinates for the rotated shape(s).
Andri Signorell <andri@signorell.net>
# let's have a triangle
Canvas(main="Rotation")
x <- DrawRegPolygon(nv=3)[[1]]
# and rotate
sapply( (0:3) * pi/6, function(theta) {
xy <- Rotate( x=x, theta=theta )
polygon(xy, col=SetAlpha("blue", 0.2))
} )
abline(v=0, h=0)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.