From: leathm AT solwarra DOT gbrmpa DOT gov DOT au (Leath Muller)
Message-Id: <199704020136.LAA01617@solwarra.gbrmpa.gov.au>
Subject: Re: ALLEGRO: get_camera_matrix normals
To: sebastion AT irelandmail DOT com (Jeff Bachtel)
Date: Wed, 2 Apr 1997 11:36:25 +1000 (EST)
Cc: djgpp AT delorie DOT com
In-Reply-To: <19970402010432.AAA7397@hometown> from "Jeff Bachtel" at Apr 1, 97 07:07:43 pm
Content-Type: text

> In the docs for 'get_camera_matrix' it mentions that xup, yup, and 
> zup need not be normal, does this also mean that they can be used as 
> a point the camera is 'looking' at? Also, what is the performance hit 
> on using floats for everything (in 3d) on a Pentium. I heard that in 
> most cases it was actually faster than fixed, is this true?

I don't know about Allegro, but everything else I have ever used (D3D, OpenGL,
etc) wants the yup of the camera to be perpendicular of the forward projection
vector (the cross product of the plane from the camera position (eye) to the
viewing position)... Does Allegro have the equivalent of a gluLookAt() routine?

Floats are usually faster on the pentium - check previous mail archives, this
was a huge topic not long ago...

Leathal.