🚀 go-pugleaf

paul@ramsey.cs.laurentian.ca (Paul Lalonde) writes:

>I'm working on a small 3D graphics program that takes vector images
>and rotates them about the XY axes.

There are 3 kinds of rotations in 3D :

x-axis rotation :
y' = y*cos(angle) - z*sin(angle)
z' = y*sin(angle) + z*cos(angle)

y-axis rotation :
z' = z*cos(angle) - x*cos(angle)
x' = z*sin(angle) + x*cos(angle)

z-axis rotation :
x' = x*cos(angle) - y*sin(angle)
y' = x*sin(angle) + y*cos(angle)

There is, of course, the more effective matrix representations of the
above, but I didn't think Paul wanted to be bamboozled with all the
matrix-algebra jargon.  Any good computer graphics would describe the
3D theory rotation well.
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Stephen Quan (quan@sol.surv.utas.edu.au)      Tel : 002 202844 (local)
Research Fellow, Computer Scientist,          Fax : 002 240282 (local)
Centre for Spatial Information Systems,       Tel : 61 02 202844
University of Tasmania, Australia.            Fax : 61 02 240282