In this course we're going to look at something a little different, creating technically accurate 3D printed parts.
# 1 30-11-2014 , 05:38 PM

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Join Date: Nov 2007
Posts: 75

#### Dynamics. A few questions

I've spent a long time messing around making models, but never really explored Mayas other capabilities. I'm thinking of a scene, that I really don't want to animate by hand. Basically, we're in a room in a ruined castle and the dead leaves on the floor start to fly around and around the room.
Can that be done? I'm sure you can create a wind and have it interact with objects and have them interact with other objects, but how well does Maya do stuff like this? Does it take how the aerodynamic properties of an object change as it moves through the air into account? Does the wind form eddies and low pressure areas in the lee of an object? Can I just create a wind and let the simulation do everything, or is it not that close to reality?
What about the objects? In this case leaves...They move the way they do in the wind because the force of the wind can cause them to twist slightly. Can objects in Maya behave this way, or are they effectively indestructable and infinitely rigid?

I have a few Dynamics tutorials, but I'm just asking if the knowledge I'm after is likely to be in them before I invest hours in watching them.

Edit: Also...what about a scene similar to the one in 300 where the spear knocks the dude off his horse? Okay, so, in the movie, the physics were impossible, but, rather than have an object hit another object and either bounce off or transfer its momentum to the other object (Or, both), what about objects like in the case of our spear? Can you have it penetrate the other object, BUT with friction so there is some energy transfer, or so that penetration stops once our spear is buried up to a point that's too wide for it to penetrate any further, after which, the remaining kinetic energy of the spear is all transferred to the poor horsemen. (The 300 scene was just an example. The best effect in that movie was giving all those actors ripped six-packs, using a magic marker and some gravy browning.)

Edit: One more question...I have the scene done, it's just a camera following a ball through some trippy obstacle course. Other than the ball, the only other things that have any fields applied are a bunch of skittles. (Well, about 200) Even in wireframe, the simulation only plays at a couple of FPS now. How much difference would caching it make? I wish I'd known about that before I started, so I didn't have to keep playing it from the start every time I needed to check something. But, for future reference, how much difference would that make to the render time? I have a few spotlights with raytracing turned on, and most of the geometry is somewhat reflective, but I've never had anything render anywhere near this slowly on this machine.

Last edited by xgabrielx; 05-12-2014 at 03:03 AM.

# 2 01-12-2014 , 02:54 AM

EduSciVis-er
Join Date: Dec 2005
Location: Toronto
Posts: 3,374
Dynamics are typically a careful balance of simulation and controlled fakery. A lot of times you will have to key changes in properties at different times to get what you want. With the example of the spear, you might end up giving the spear a huge amount of mass, and then drop that just at the right time, or increase the friction suddenly.

With the leaves, again, you can set up nCloth objects for the leaves so they flutter and bend, and set up turbulence and wind fields that span certain areas so that you get the effect you are after. Mostly it is a long process of tweaking, testing, and running the simulation again and again to figure out the look you are after.

Hope that helps.

# 3 01-12-2014 , 04:35 PM

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Join Date: Nov 2007
Posts: 75
Ahh, good. As long as you can tweak all the right variables, it's good. And, it sounds like you can. Never thought of using ncloth. I've never played with that before either.

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