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paulselhi

R12 Dynamics

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  • OK i was definitely the scale setting but still R12 dynamics is very tricky to get accurate results, i manged the scene below after a lot of tweaking but still there is some jitter ( some may be AA but i think it is mainly sim stuff) one capsule goes a bit ape$hit and decides to leave the party very early. The GI seems quite stable on a cached sim. For this ism i removed the vast majority of the capsules as i was really testing then for capacity handling but still the thing is memory hungry and for this sim i would say you need at least 4 GB RAM

    What is annoying about all sim programs is often you have to raise the substeps to get correct collision detection but the high SS can use the Ape$hit effect with objects flying in to the void. Getting that happy medium between good calculations and substeps if often quite hard. Silverbullet does a better sim far more easily but overall i like the look of the whole R12 package, springs connectors motors etc, I will have to stress test them to see how viable they are in real scene sims

    http://www.black-and-white-to-color.com/stuff/pillsr12.avi

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    That looks pretty cool. I'm just rendering a fun animation now and will post later once it's finished rendering.

    3DKiwi

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    I feel a Dynamics Cafe Challenge coming on :)

    I've just been fooling around with Dynamics this afternoon and will post a simple animation once it's finished rendering. It's so much fun to play with.

    Nigel / 3DKiwi

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  • Perhaps an earthquake sim ?

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  • Note by default dynamics objects have their linear and angular damping set to zero. It may be better to set these to something like 8-10 to get some realistic drag, note this is not friction on an object to object level

    Also the resting ( stop jiterring) is controled in the scene dynamics settings with "restitution lifetime for resting contact" - what a load of techno babble !! This sets when the inbult jitter dies off. i assume the objects the pass to an inactive sleep state with an awake on collision effect

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  • I think that is the case, not sure if it could freeze objects in mid air or wheter gravity would overide it

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    Linear and angular dampening can freeze objects in mid air even with gravity. I think of it more like a universal friction for the objects. If the friction is to high it will not move.

    To stop the jitter I would up the Linear/Angular Velocity Threshold or up the Maximum solver iterations per step under Ctrl+D or change the collusion shape from Automatic to moving mesh or all three.

    Edit: By the way very cool animation and render. Is that Vray?

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  • If you mean mine, no it is Sky sampler GI. Done in demo but enlarged and saved images out to avi in R11, hence the poor detail

    Another point worth mentioning, if you are working with very small objects like pills don't bother tearing your hair out using real world scales like a 4 cm capsule. It is just to much hassle to get the sim to work. The dynamics seem to work much smoother with default scales so try a default sized capsule and build the rest of the scene based on that scale. Collision detection is far better.

    If I can I think i will change the title of this thread and loose the slow !!

    Also if you create a box with thickness and no lid ( a tray !!) and drop capsules into it you make be put off by the viewport showing the capsules pushing through the sides. I see this when i have my VP set to hidden lines and wireframe. But render the view and there are no intersections. To get a clean view switch from wireframe to isoparms

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    Got to admit it, this dynamics implementation is pretty cool. If I had this, I would never get any work done!

    How about this. I thought I would give it a challenge. A bike! I made a frame and 2 wheels. Applied dynamics. Pressed play. It fell to the ground then fell over. As expected. Put a motor on the back wheel. Not much better. However I experimented a bit with the motor speed and torque. Also, I had used toroids for wheels, so I experimented with the pipe radius.

    Bugger me, but I found a setting where it dropped to the floor, wheelied a bit, the front wheel hit the ground, it wobbled then shot off, BALANCED, weaving slightly like a real bike. If you have too much torque or motor speed, it crashes like a real bike too.

    I am impressed.

    I'd save the file if I could.

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    I am impressed.

    I'd save the file if I could.

    Just register and you can save it for 42 days. :)

    Peace,

    Rich_Art. wink.gif

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