Path: chuka.playstation.co.uk!news
From: Majik <majik@127.0.0.1>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: libps - RotMatrix()
Date: Fri, 26 Oct 2001 14:52:05 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Martin Keates wrote:
> 
> That makes y roll not pitch, and x,y,z is basically pitch, roll and yaw.
> 
> > RotMatrixX(x, mtrx);
> > RotMatrixY(y, mtrx);
> > RotMatrixZ(z, mtrx);
> 
> This is not quite right. 
probably not, I was doing this from memory, after having left a screen
full of 'GPU unsupported code 0..' at 2:00am last night ;)

> Also, you need to make sure you keep your rotations within a
> suitable range. Anything for roll and yaw, but pitch needs to be
> within -90 to 90 degrees.
the roll is limited to be just a banking angle, so the plane (and
viewpoint) leans into corners, the direction (yaw??) the planes move in,
and the pitch are unbounded.

> I don't think you'll get any sort of Gimbal Lock problem here.
I think that's what I encountered, and eliminated.

> When
> pitch is +/- 90 degrees the plane will be vertical so you probably
> won't want it to be moving along the y axis. But it should have the
> correct orientation.
it seems to work as expected now.

> Presumably you move the planes on the
> z-axis as well as the y-axis depending on their pitch. You could
> get the direction vector of the plane by putting (0,1,0) through the
> rotation matrix.
transposition matrix is made up from taking the pitch and yaw angles,
and combining them with a fixed distance and putting the whole lot
through a spherical to cartesian coordinate transformation. It sems to
work :D

M.