ph_setgravity(earthgravity)
- is a global instruction. It only needs to be called once

action plane{}
- 3DGS ODE physics respond to non-physics entities as well, so this is not necessary.

ph_setautodisable()
- Another global function. Your entities are automatically disabled when the game begins, because ODE assumes their in a "safe place". This helps the game load without needing to do collision checks for every entity.

phent_addvelcentral(my, vector(0,0,1));
- Put this at the end of your Ball() function. It will add a very small velocity to your object, so that physics are enabled at start.