Hello guys!
I hope this will be the right place for this post. I have a question regarding the use of camera(); I tried to set it up so that it revolves around an object that was placed in the middle of a scene. That is; no z-depth. I then used sin and cos to make coords for the camera to follow, making it a big circle, always pointing towards the middle of the scene. This worked pretty well, but it looked to me as the camera was running an elliptic path rather than a perfect circle path.

Here's an example code:
Code:

float camrot;
void setup(){
  size(600,600, P3D);
  stroke(0);
}
void draw(){  
  background(200,100,140);
  translate(width/2, height/2, 0);
  box(140);
  // camera(eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ)
  camera(sin(camrot)*1600, height/2 ,cos(camrot)*1600, width/2, height/2, 0, 0, 1, 0);
  camrot += .025;
  camrot %= TWO_PI;
} 

Any ideas/hints?

it's the translate, i think, affecting the lookat. you don't really need it - the camera is defining the middle of the screen now.

remove it and change the camera line like this:

camera(sin(camrot)*1600, 0 ,cos(camrot)*1600, 0, 0, 0, 0, 1, 0);

and it looks like it should.

Thank you all for quick replies I still feel sort of confused, but thanks to the hints I now have the camera rotating around an axis. I guess it was that in the first place as well, but my object was not centered in the middle. I didn't think that the translate had any effect on the camera in this test code, but it seems it did. But, now, why is it that the box is not in the middle, i.e. on the y-axis, when I place it in the middle of the canvas? (ah, re-reading what I wrote, I think I understand better now. There are no axis in the middle of the canvas, they are at x=0 and Y=0 of course! )

I can see the effect now. By just placing the object on coords (0,0,0) it appears as though they are in the middle of the canvas (and with my new level of understanding, it now _looks_ like it is the middle of the canvas, because I told the camera to point that way, i.e. on the y-axis, right?) ... Well, interesting and cool Thanks again!

koogy wrote on Jan 22^nd, 2010, 1:14pm:

Well, you were right about translate having something to do with it, but yes, I agree, using the 0,0,0, as a reference seems the easiest now Thanks!