mac osx maya 2009 plugin

[cgbeige]

so everyone once in a while, I get an unstable start but it doesn't always fix itself the second time around:

http://www.3eige.com/cgtalk/bullet3.mov

Is there a way to avoid that? If I bake animations, half the time, it's the bad sim.

[RBD]

is it normal that I have to run the sim twice to get the initial velocity to kick in (like the array layout)?

Well, like I wrote before, it's always a good idea to rewind your scene after making any changes to rigid bodies to allow Dynamica to reset itself.

sorry if this is covered somewhere else in the forum but I can't wrap my head around how the hinge is supposed to be set up. I am getting some crazy behaviour with a hull mesh and a hinge

I don't know about the new constraints, Herbert Law, who added the constraints functionality to Dynamica wrote a little guide (see bottom of page): Issue 221: Fix and Extend BulletMayaPlugin

so everyone once in a while, I get an unstable start but it doesn't always fix itself the second time around: [...]Is there a way to avoid that? If I bake animations, half the time, it's the bad sim.

If your simulation starts off with interpenetrating objects, they will explode like that; you should avoid having rigid bodies interpenetrating at the start of a simulation to avoid explosions. It definitely looks like the object you are using as a floor is colliding with the bricks, try moving it lower. It looks like you are using a cube primitive for a floor; note that cube primitives have an extra collision margin around them, a small gap of about 0.04 units, so you can't line up a cube primitive right up against another rigid body because you will start off with an interpenetration / collision, and therefore a potential explosion. (Plane primitives are ideal for floors.)

By the way, with my Bricks on Curve script, you can close your curve and the bricks will line up and form a continous wall.

[cgbeige]

okay - thanks. so it seems like everything's working normally then? The baking works nicely - any chance you'll be getting mesh baking to work some time? That's the only thing really missing from using this in my simple scenes.

[RBD]

any chance you'll be getting mesh baking to work some time? That's the only thing really missing from using this in my simple scenes.

Well that's the whole point of my new dynamicaHullMeshForEasyBake.mel script... it, along with the updated dynamicaBake.mel allow users to bake hull and mesh Dynamica rigid bodies! Please read the RBDTools thread carefully, thanks.

[cgbeige]

ok - last (hopefully not stupid question). How do you keyframe the velocity of an object? keyframing initial velocity doesn't work.

[RBD]

[...]How do you keyframe the velocity of an object? keyframing initial velocity doesn't work.

You can't. You can set an initial velocity, but when the simulation starts, the velocity at any moment in time is computed from the forces at play (otherwise there would be no physics simulation). Similarly as with the real world, the way to change velocity during a simulation is to exert a force on an object; perhaps you could keyframe a Maya force field (e.g. a uniform field) and have it follow a rigid body?... I just tried it and it works very well: I created a uniform force field (with a volume shape to fit inside the rigid body) made it the child of a rigid body, then keyframed the magnitude (0 = no acceleration) and direction; it becomes an acceleration controller for the rigid body... very neat.

[cgbeige]

great - thanks.

[cgbeige]

my scenes aren't opening with the initial state working correctly. arrays are moving unpredictably.

[RBD]

my scenes aren't opening with the initial state working correctly. arrays are moving unpredictably.

I assume you mean after saving, make sure you rewind your scene before saving, I reported this bug earlier, see this thread: Dynamica Bullet for Maya Issues & Wish List