If you have Max 2013 and are on Subscription, I highly recommend updating all service packs and downloading the MassFX extension for Particle Flow. It used to be known as ToolBox#2 and will do what you want. At least I’m pretty sure it will. If you’re not on subscription, you can still buy Toolbox#2 for about $600.
I suggest that you make simulation of the big rock (as single geometry) and attaches the fragments (many small parts) to the rock geometry till the frame that rock touches the floor… then make simulation to the fragments as kinetic from beginning till that frame and then as dynamic ...
it is retarded method in the time of many software make hall process from fragmentation to end of simulation automatic and in real-time !
I’m a Maya user so my terminology might be a little different than 3DS but I’ll try to use generic terms.
First, you need two different sets of models. 1) your rock in its unbroken original state. and 2) your rock broken into pieces.
Now, take the unbroken rock and set up the simulation so it falls and hits the ground. Cache the simulation. Now, at the frame right before the rock hits the floor get its dynamic info, that is, its velocity and such, and take note of it some where.
Now, take the shards, place them exactly where your whole rock is now before its about to hit the floor. Set the initial dynamic properties for the shards to those that I said note of before. And run and cache the simulation from that frame.
Finally, you just have to key frame the visibility of the rocks. First, have the whole rock visible from the beginning of the animation until right before it hits the ground. Then, have the rock shards not visible until the frame that you make the whole rock invisible.
That would be the most direct and manageable method to getting this effect.
I don’t know how MassFX works, but in older Max versions, reactor would get the initial velocity from keyframes you set for your object before the simulation starts. So if your sim starts at frame 10, you would keyframe animate your objects falling down from frame 5-10 or something.
3ds Max 2009 SP1, 2010 SP1
Windows 7 Professional 64-bit
Dual Intel Xeon E5520, 6 GB Ram
NVIDIA GeForce GTX 460 OC
If you go that route then the objects need to be defined as Kinematic and set the Until Frame appropriately.
There are also options within the MassFX Modifier to set an Initial Velocity (which I’ve not tried) on the Advanced rollout.
Max 4.2 through 2014, Composite 2014.
nVidia 9800GTX+ (512MB) (Driver 314.22).
i5-3570K @ 4.4GHz, 8Gb Ram, DX9.0c.