TIB: 3d coordinate graphing

To: ti-basic@lists.ticalc.org
Subject: TIB: 3d coordinate graphing
From: osprey@nwinfo.net
Date: Mon, 01 Jun 1998 22:41:17 -0700
Delivered-To: ti-basic-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: ti-basic@lists.ticalc.org


Hello, i would like some help with the math in graphing a 3d point on my 82.
It seems all you need to do is translate the the x,y,z coords a certain
amount so they appear '3d' on the 2d screen.  Imagine the z-axis coming out
of the screen:
                      x-axis
                        |
                        |
                        |
                        |_______  y-axis
                       /
                    /
                 /
              /
           z-axis

My question: Does anyone know a simple way to translate a 3d point onto the
calc's 2d screen?  I'm pretty sure it involves a rotation matrix like
[ cos X       0     ]
[    0       -cos X ]
                                where X is the angle

Also, does anyone have info on using a viewpoint in calculating the 3d
point's relative position?

Thanks for any info
Ben
osprey at nwinfo dot net