I need to build a model of the solar system ... I can build models with MED and as you can guess I build the system all in one model, this was ok and looked nice when I used rotate. But I'd like to build all the planets and sun as their own ENTITIES. How would I then get the planets to revolve around the sun and at different speeds and distances. If any one knows of some code examples or a quick snippit to point me in the right direction would be huge .... thanks.

Like many solutions there is a large scale way of doing this, and a low scale solution of doing it. If I can assume your only building one or just a few solar systems and not a whole galaxy of them, this would be fairly simple.

The sun is the key to this, make a global array and a counter, set the counter to 0 at the start of the game. In your sun action, assign a pointer to the sun in the array[counter] slot and then increment the counter.

Every planet that you want to revolve around these sun's you create you simply assign a number according to the sun that you want them to revolve around (first sun would be 0, second sun would be 1 ect.). Then you just assign your movement code to reference array[currentSun].x, array[currentSun].y, and array[currentSun].z to find the position of the sun you want.

I'll assume you already have the code for revolving around the sun. But this should be fairly simple to do, so good luck.

Here.. i've just built this...

http://www.coniserver.net/ubb7/ubbthreads.php?ubb=showflat&Number=221348#Post221348

Wow ... thanks, that's just what I was looking for ... :-) Nice code. I have a few other dilemmas, what about an elongated orbit ... like an asteroid or comet. How would I teach these objects to be aware of each other ... and know when they are close to one another or side by side??

I haven't looked at the code he gave you but there are two ways of doing what you ask. The hard and most flexible way is to implement gravity physics into your code where the asteriod scans the planets and such for their mass and based on its proximity moves based on the gravity that effects it. The easy way and less flexible way is to give the asteroid a uneven radius (x has one radius length, and y has a different one) this would give an oblong path of movement, and then you would place its origin wherever you deem appropriate, but all of this would be manual, but very easy going on your computer.