[cad-linux] Re: database access methods

Jim,
gluLookAt() does what you have in mind. If you want to know what it's
doing look at the Mesa sources. For an explanation have a look at the
"Red Book". 
Regards,
Roland

--- Jim Parker <hopeye@xxxxxxxxxx> wrote:
> 
> On 2003.05.16 12:06 Roland Krause wrote:
> 
> > >
> > > viewer.  Does anyone know a simple routine to convert a vector to
> > > OpenGL rotation angles ?  You can not use simple force resolution
> > > routines.
> > 
> > Do you mean a virtual trackball that allows you to rotate the scene
> or
> > a camera? I have both, let me know what you need. They are from the
> > net, if you google for virtual trackball you will find them.
> > 
> > Roland
> > 
> > 
> 
> Not quite.  An example should help.  Suppose your model is centered
> on 
> a global orthoginal right handed coordinate system.  You are at a 
> arbitrary distance far enough away to see the entire model.
> 
> If you are looking down the Z-axis at the X-Y Plane.  The orientation
> 
> unit vector would be: (0i + 0j + 1k)
> 
> Now let say you want to rotate the coordinate system so you are
> looking 
> down the X-axis at the Y-Z plane.
> The new orientation vector is (1i + 0j + 0k).  This requires a 90 
> degree rotation about the Y axis in OpenGL.
> 
> Now it is easy to write a simple if-else code block for the six major
> 
> faces.  What I am looking for is a general routine to handle any 
> arbitrary vector.  An example would be a isometric view obtained by a
> 
> 30 degree rotation about the X-axis, then another 30 degree rotation 
> about the Y-axis.
> 
> Like I said in my previous post, you can't simply extend the force 
> resolution routines.
> 
> thanks for your help.
> 
> cheers,
> Jim Parker
> 

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