On 1/21/2013 5:28 AM, Kenneth wrote:

>> - there seem to be some "collisions" (rocks passing through each other)
>
> I was wondering if anyone would notice that. So far, I count only one, but there
> are probably others. I toyed with the idea of writing some kind of code for
> collision detection or whatever, but got bogged down in the details; so I opted
> for an easier scheme of random meteor placement, but one that's not *quite* so
> simple as <rand(...),rand(...),rand(...)>. The final construction is actually a
> cylindrical 'tube' full of objects (with a central tube carved out for the
> camera to move through.) There are multiple seed() values for this, to give me
> at least *some* control over the situation. If I had taken enough time, I could
> probably have found a set of values to *totally* eliminate the few collisions.
> But real collision detection is obviously needed.

Actually you can get away without collision detection on a fly-through 
like this by simply having each asteroid stay in place, and have the 
camera take a more winding route.  The spinning of the asteroids and the 
motion of the camera will help hide the cheating.  After an asteroid 
belt has been in place for a few thousand years, the relative motion of 
the asteroids is minimal.

(If the asteroids are moving relative to each other, then they will 
collide.  This will cause a loss of energy--converted into heat--which 
will cause one or both of the asteroids involved to fall out of orbit.)

If you still want to have a few asteroids moving through the field, then 
code a few non-intersecting cylinders at varying angles, add a 
spherical-sweep path for your camera, and then  fill the space around 
them with non-intersecting spheres.  Put stationary asteroids where the 
spheres are located and have the moving asteroids move along the axes of 
the cylinders.  (Don't put the cylinders or spheres into the scene, just 
have code calculate where they should go.)

Regards,
John

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