# comp.graphics.algorithms

## Subject: Re: Lineal algebra problem

"Hans-Bernhard Broeker" wrote in message
news:4aklbbFtg0i7U2@news.dfncis.de...
> guanaco wrote:
>> Positive "x" is at the right and positive "y" is up. I need to move the
>> camera to a point P1 (the look-from) pointing to another point P2 (the
>> look-to). Is there a general procedure to do this with translations and
>> rotations?
>
> Not really. No. The problem is that eye point and look-at point
> combined don't fully fix the orientation of your camera. You still
> have to determine roll (around the view axis), and potentially other
> parameters, like field-of-view / focal length.
>

presumably, the camera is already "upright", so no need to consider roll;
field of view is unchangable.

in this case, the answer becomes simply:
move camera;
point at target.

and the "point at target" can be defined as 2 angles.

"better" answers imply a more fluid definition of the camera, eg: can/has to
deal with arbitrary orientation (and a possible seperation of world and
local space);
can adjust things like field of view (implying some notion of "how big" the
object being looked at is relative to the camera);