[gvDan]

The question here is regarding the difference in efficiency between two methods of calculating collision of an object with a sphere: hitTest( ), and some simple math.

The question has arisen purely from doubt as to what happens at the core of the hitTest method. [ I know this is somewhat trivial, but if it really makes a difference then I guess it's worth discussing. ]

Actionscript:

//  sphereMC -   for this example, it is a FILLED sphere, to insure that hitTest detects the object
//  myObject is simply a point.

//  1)  hitTest( ... )
if (  sphereMC.hitTest( myObject._x, myObject._y, true ) {
     // ....
}

//  - - - - - - - - - - - - - - -
//  2)  simple math
//  
radius = sphereMC._width/2;
dx = myObject._x - sphereMC._x;
dy = myObject._y - sphereMC._y;
distance = Math.sqrt(dx*dx + dy*dy);
if (distance < radius) {
   // ....
}