🚀 go-pugleaf

Ok, here we go.  First of all I would like to thank all the people that
were kind and knowledged enough to reply to my cry for help.  I received a
lot of mail and postings that helped me to find some new books to look
through and some actually sent me some code.  I tried to reply to all of
you who sent me something or posted something, but I am sure that I missed
a few...so if you didn't already hear thanks, then thanks.

Next, in most of the replys I got people rehashed just what I have already
been doing.  Here is my most immediate problem in a lot more detail.  

I can draw and rotate an object on the screen around the x, y and z-axis
all day long.  The only problem is that each axis that I rotate
around is the corresponding axis of the monitor (what you actually see).
Now, what I want to do is to be able to rotate the object around its own
three axes (virtual axes).  For example, say the object is a tetrehedron
with its base in the xy plane (the yz plane is sticking in your face) and
its top point in your face.  The object is situated so that the z-axis is a
line running though the top point and the middle of the base.  Now say that
I rotate this object around the x axis about 30 degrees so that the point
is now partially up the screen.  Now if I was to rotate the object about
the z-axis as my code now exists, the top point of the tetrehedron would
sweep out a circle on the screen.  This problem could be solved by doing
the rotations in a certain order, but that screws up as soon as you rotate
about the third axis.  What the object should do if it is rotated about the
z-axis (its z-axis) would be to spin along the imaginary line running
though its top point and its base.  But alas, I cannot get this to happen.

In consulting a few graphical technique books, I found out exactly how to
do a rotation about an arbitrary line.  I figured that if I kept the axes
of the object in the data of the object itself and rotated the axes along
with the object, then I would be able to do an arbitrary rotation about
those axes and voila, it would work.  I tried this and have had no luck.
My code has been gone over with a fine toothed comb (my own and a friends)
and no problem can be found.

If anyone has experience in this area of 3D rotation, please keep posting.
If I am just missing a small point, don't flame me.  I will see it soon
enough.  I am bound to find out what I am missing eventually.  All your
help is appreciated.

Thanks a lot, Keith Murray


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	CHAOS Software			Software for someone...
						
	1360 NW VanBuren		Keith Murray  a.k.a. Slammer
	Corvallis, OR  97330		murrayk@prism.cs.orst.edu
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