Thanks to Matthew!
This is the best "plain english" definition I've seen. I have asked this
question before myself and never gotten an explination that didn't hurt my
brain.
Thanks again Matthew!
Don
-----Original Message-----
From: Matthew Pocock [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 18, 1999 8:31 AM
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] Transform3D Coordinates
Hi.
I am not a mathematician, so can't give a detailed account of the 16 numbers
in
the transform3d, but I can talk you through how they work.
The transform looks like this:
xx xy xz tx
yx yy yz ty
zx zy zz tz
sx sy sz ss
You can see four areas of numbers. The upper left block are the
rotation/scaling/shearing ones. By default they look like:
1 0 0
0 1 0
0 0 1
This means that after the transform has been used that x will remain x, y
will
remain y and z will remain z. If it was
0 1 0
0 0 1
1 0 0
it would mean that after transform, the new x would equal the old y, the new
y
would equal the old z and the new z would equal the old x. By putting more
complicated numbers in there, the new xyz can be made to be any combination
of
the old xyz coordinates. These numbers are best set using the shear, rotate
type
methods on transform3d.
The tx, ty, tz parts of the transform transform a point. So,
0
1
-10
would move your point forward one along the y axis, and back 10 along the z
axis. These values are best set using the translate methods.
The sx, sy and sz parts are used to inverse scale the scein.
10 1 1/5
would make the resulting scein 10 times smaller in the x direction and 5
times
larger in the z direction. Use the scale methods in the transform3d class to
control these. Lastly, ss inversly scales the entire scein.
Basicaly, don't try to figure out what all the numbers meen. That is what
makes
object-oriented programing so great! Use the methods in transform3d to build
your transform in a way that you understand. Don't worry too much about how
it
works.
Matthew
Juan Jos� Abenza Moreno wrote:
> Does anybody know what is the meaning of each one of the 16 coordinates in
a
> Transform3D?
>
> Thanks,
> Juan Jose Abenza
> [EMAIL PROTECTED]
>
>
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