hey all

i'm trying to rotate objects on the surface of a sphere and test to see if they hit each other.

I've worked out the simple 2D rotation, but can't figure out how to rotate on the Z axis as well (shouldn't have napped through high school maths). tried to read up on it, but been going round in circles for hours.

and secondly how would i test for the collision on z-axis as well.
Something tells me i should be using Vectors

any help appreciated.
here's the code so far:


Code:

class Circs{
 float x, y, z, angle, speed; 
 float sphereSize;
 int me;

Circs(int _me, float _angle) {
 angle = _angle;
 me = _me;
 sphereSize= random(15, 40); 
 speed = random(-1, 1); 
 if (speed > -0.1 && speed < 0.1) speed = 0.4;

 } 
  
void draw(){
update();
fill(255); 
pushMatrix(); 
translate(x, y, z);
sphere(sphereSize);
popMatrix();   
hitTest();
  }
  
  void update(){
angle += radians(speed); 
x=cos(angle)*(radius/2+sphereSize/2); 
y=sin(angle)*(radius/2+sphereSize/2); 



  }
  
  void hitTest(){
  for (int i=0; i<circs.length; i++){
  if (i != me){
 float dist = distance(circs[i].x, circs[i].y, x, y) / (circs[i].sphereSize-2 + sphereSize-2);
if(dist < 1) {
speed*=-1;	  
circs[i].speed*=-1;
update();
}

  }
  }  
  }
  float distance(float x1, float y1, float x2, float y2) {
  return sqrt(sq(x1-x2) + sq(y1-y2));
}
}
 

ah, thanks.
but seemed using PVector and just normalising the vectors is the easiest way to go. will post the code once i've sorted out the hitTest.

cheers
g