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Demiguise
12-24-2010, 04:37 PM
Hello Thar,

I'm trying to roughly make a scene which involves a solar system being created out of a nebula. However, I'm having a spot of trouble in figuring out how to make the initial nebula turn into a disc which is most regularly shown on the discovery channel, etc.
I've tried using a vortex space warp, but all that does is slowly push the particles outwards into a ring, rather than a disc. I've attempted to balance out the forces using gravity, but that only changes the moments before the ring is made and the size of the ring, nothing else.
Past that, I think I can get some things working, small particle events working in orbits.
The last trouble I think I have is the creation of the planets, I was considering creating small spheres that eventually turn into the planets and have them scale up but I'm interested in turning the particles into a solid object. Seen in this video: http://www.youtube.com/watch?v=Jz-7Di2s4yY&feature=player_detailpage#t=6s

Any help would be much appreciated.

cgCody
12-24-2010, 09:30 PM
Getting the nebula to spin into a disc should be easy enough just with a gravity space warp (or a few). You just need to spend some time playing with the gravity strength and decay (Or do the math, if you're up for it.).

I was recently toying with this to get a working solar system. Here's a video (http://www.screentoaster.com/watch/stUExVR0dIRFtWQVRaWFheV1JU/pflow_orbiting_planets). In that same scene, I tried simulating a galaxy, which came out pretty similar to our own, before Max choked on the millions of particles.

Anyway, as for getting the nebula to form into planets, an interesting idea - if you're wanting to go the physical simulation route - would be to create a second particle event, with just a few particles orbiting around the nebula center. With a trivial bit of maxscripting, you can attach gravity space warps to these particles, which can be used to clump the nebula particles together. You might even go a step further, and increase the gravity strength, as more particles clump together. And of course Box#2 or Box#3 would be great for getting physical chunks to collide with one another. :)

Demiguise
12-25-2010, 08:16 PM
Thanks Cody.

I must admit, I am rather ill-experienced with particle flow. I know some of the things it can do but am lacking the basics of it all I think. Of the tutorials that I have found on the internet, I couldn't seem to find any that provided decent examples for me to work with :/

I've tried using a gravity space warp on the nebula, but all I can get is a bubble slowly collapsing and then expanding again. The vortex modifier also just spins things out of control and towards a ring, however I play with all the settings that I can. The math I could do, If I knew what did what and how it would play with everything else. Did you model the mass of the sun and earth in your example?

Quite frustrating that I can't quite find any books on the subject either, only physics ones that don't help that much :D

cgCody
12-26-2010, 03:58 AM
I tried playing with this idea, earlier. The gravity space warp is definitely the way to go. It just takes some delicate fine tuning with the settings, before the particles become stable. In my test, I had a nebula that was about 200 default units in xyz. I had a spherical gravity with strength and decay at 0.05. I threw a motor space warp in there, running from frame 0 to 10, just to get some circular motion. After this, gravity took hold, and the nebula started to flatten out into a spinning disc.



Here's something you should do that will really help you visualize the motion of your nebula:
Set your nebula event to spawn just a few particles (Or use the visibility setting). Add a spawn test to the end of this event, and plug this into a new event with a display node. In the spawn test settings, select either per second, or travel distance. Scroll down and set Inherited to 0.

Move the time slider forward a few hundred frames. Now your particles leave behind a trail. You can use this visual cue while playing with the settings for your space warps. Instant feedback on how changes in settings affect the motion of your particles. :)

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