i am trying to make the camera orbit spherically and have modified an example about orbiting on one plane (the x-z plane to exact) this is what i have so far:

1. float xrotation=0;
2. float yrotation=0;
3. void setup() {
4.   size(500, 500, P3D);
5.   background(255);
6. }
7. void draw() {
8.   background(255);
9.   lights();
10.   xrotation += mouseX-pmouseX;
11.   yrotation += mouseY-pmouseY;
12.   float orbitRadius= 200;
13.   float ypos= sin(radians(yrotation))*orbitRadius;
14.   float xpos= cos(radians(xrotation))*orbitRadius;
15.   float zpos= sqrt((orbitRadius*orbitRadius-xpos*xpos-ypos*ypos));
16.  
17.   camera(xpos, ypos, zpos, 0, 0, 0, 0, -1, 0);
18.   box(25);
19. }

now sometimes the box disappears and im not sure why i may not have the right equation for ypos but the other two should be solid... i think lol. does anyone know why this might be happening>?