**comp.graphics.algorithms**

## Subject: **Re: Lineal algebra problem**

"Hans-Bernhard Broeker"

news:4aklbbFtg0i7U2@news.dfncis.de...

> guanaco

>> 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.

>

in my case, for my answer I made the assumptions:

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);

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