I'd like to program a virtual camera.

Now before you jump right on it, let me say that I want to avoid using camera(), beginCamera(), or the OCD camera lib. All of which are wonderful, but I can't use them since I have no control of the internal matrix stacking.

So my question is: how does one write a camera routine?

I want what basically is a (6dof?) camera system used in the most basic FPS games (think Quake). I want to do this with good ol push pop matrix, translate, and rotate.

The problem I'm running into is what order to rotate/translate. As of now:

Code:

  translate(cameraSourceX, cameraSourceY, cameraSourceZ);			     
  rotateX(cameraRX);    
  rotateY(cameraRY);
 

This isn't correct, since the rotation axis will always be at the center of the world (0,0,0) and the scene becomes basically a "model on a turntable". I want the rotation axis on the viewer (from your head).

So I tried:

Code:

 
  rotateX(cameraRX);    
  rotateY(cameraRY);
  translate(cameraSourceX, cameraSourceY, cameraSourceZ);			    
 

Which is also incorrect. The rotation is now locked onto the viewer's head, but the translate is locked into the world's XYZ axis.

I know there's a particular order in which to do this (and also an additional step to reverse a translation) but I can't, for the life of me, seem to find this through google or NeHe.

Help. Please!


OOPS I just realized this should be in the 3D forum. Please move this, thanks!

*edit after reading all of source*

Ahh.. alas....

It's using

Code:

  beginCamera();
  camera(cam.pos.x, cam.pos.y, cam.pos.z,
  cam.view.x, cam.view.y, cam.view.z,
  cam.up.x, cam.up.y, cam.up.z);
  endCamera();
 

Correct? I want to try doing this without any form of camera(), since I want to maintain my own matrix transform stacks. I see that you're doing some heavy math (quaternions.. no less...) to achieve the billboarding.

I am doing billboarding with screenXYZ (and playing with modelXYZ as well to some success) which works (without additional math) but I still need control of the camera.