I've been experimenting with using the camera() function to navigate around a sketch.  Apparently I don't understand the Up vector .. or possibly there's a bug??

Here's a test of the Up vector, simplified as much as I could do:
 http://www.backspaces.net/files/testcam0/applet/

Note that if you have the java console up, you'll see the modified Up vector as you use the x,y,z and - keys to test the camera() function.

Here's what I think I'm doing: drawing a box and rect, with X,Y,Z axes drawn and labeled.  We use
 camera(width,width,width,  0,0,0,  upX,upY,upZ);
with upX,upY,upZ being set by keystrokes and starting with 0,0,1.

It seems to me that the results are "backwards" from my expectation .. I'd presume a +1 upZ would give me the Z axis pointing up rather than the down I end up with.  Ditto with the others.  The "eye" and "center" coordinates do seem to do what I'd expect .. so I guess I'm just confused by the Up vector.

Is this the way its supposed to work?

Owen

Here's the code, or just look at the source in the applet:

float upX=0f, upY=0f, upZ=1f;

void setup() {
 size(500, 500, P3D);
 textFont(loadFont("AmericanTypewriter-Bold-24.vlw"));
 framerate(5);
}
void draw() {
 background(200);
 stroke(0);
 fill(255);
 camera(width,width,width,  0,0,0,  upX,upY,upZ);

 box(100, 100, 100);
 rect(-200,-200,400,400);

 float len = width/2;
 line(0,0,0,len,0,0);
 line(0,0,0,0,len,0);
 line(0,0,0,0,0,len);
 fill(color(255,0,0));
 text("X",len,0,0);
 text("Y",0,len,0);
 text("Z",0,0,len);
}
void keyPressed() {
 switch(key) {
 case 'x': upX=1f; upY=0f; upZ=0f; break;
 case 'y': upX=0f; upY=1f; upZ=0f; break;
 case 'z': upX=0f; upY=0f; upZ=1f; break;
 case '-': upX=-upX; upY=-upY; upZ=-upZ; break;
 }
 println("Up vector: ["+upX+" "+upY+" "+upZ+"]");
}

OK, how's it work?  

Pointers appreciated.  I looked at
http://glprogramming.com/red/chapter03.html

It seemed that the up-vector specified there was the same as I tried in my experiment.

Owen