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Poser - OFFICIAL F.A.Q (Last Updated: 2024 Dec 26 9:02 am)



Subject: Animating gravity and a bounching ball....


BachN4th ( ) posted Sun, 23 March 2003 at 11:53 PM · edited Sat, 03 August 2024 at 5:17 PM

I hope this is appropriate here, I know everything here seems to be working with still renders, but I don't know where else to post my questions about animation in Poser. I'm using poser 5, using a simple football starting in the air. I skip ahead 30 frames, drop the object to the floor and add a keyframe. Put it back in the air 30 frames later, drop again... etc etc ad naseum. Then I've been attempting to edit the y trans spline curve into something that that barely resembles gravity. ;) I'm hoping there is some kind of "gravity spline" or something I can use to do this, but I'm fairly new to poser. Also, would there be an easy way for it to generate the bouncing based on gravity so that the bouncing decreases until it finally stops? If there is a better place to post this, or find the info myself, I would be most thankful. ;)


ockham ( ) posted Mon, 24 March 2003 at 12:38 AM

There isn't a "gravity spline" as such. But the spline is pretty close to a parabola. Technically I think it's a cubical (3rd power) curve, but for practical purposes it's close enough. If you introduce a Spline Break at each of the bounces, you should be able to persuade the spline to look right. The bouncing sounds like a job for Python. Let me try it and see....

My python page
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ockham ( ) posted Mon, 24 March 2003 at 1:56 AM

Attached Link: http://ockhamsbungalow.com/Python/Gravity.zip

Here's a first try. The bouncing doesn't work yet because I haven't figured out a mathematically honest way to put in elasticity, but it does produce a single mathly correct fall to the ground. Start your ball at a high point; set up animation frames and give the horizontal movement.

Activate the script, fill in the name of
the prop and the "real" height in meters.
Hit "Fall once", and the Y movement of the
prop will be properly gravitational.

(I'll keep working on the bounce tomorrow;
right now it's bedtime!)

My python page
My ShareCG freebies


hauksdottir ( ) posted Mon, 24 March 2003 at 2:52 AM

Acceleration in a fall is 32 feet per second squared?


HaiGan ( ) posted Mon, 24 March 2003 at 7:41 AM

Acceleration due to gravity is 9.81 m/s (don't know that in non-SI units) unless there is a significant contibution from air resistance/drag (for example, when close to terminal velocity). For your ball, you needn't worry about drag. For a mouse falling out of an aircraft you would. :^p


ockham ( ) posted Mon, 24 March 2003 at 2:16 PM

file_51599.jpg

Okay, the bouncing works pretty well. This image is a ball before applying Gravity....

My python page
My ShareCG freebies


ockham ( ) posted Mon, 24 March 2003 at 2:17 PM

file_51600.jpg

Here's the settings applied by the script:

My python page
My ShareCG freebies


ockham ( ) posted Mon, 24 March 2003 at 2:18 PM

file_51601.jpg

And here's the result. The script is in freestuff/Utilities, named Gravity. The ZIP contains a readme with operating instructions.

My python page
My ShareCG freebies


BachN4th ( ) posted Mon, 24 March 2003 at 4:44 PM

Wow, thank you so much!! I've tried the first script already, and I'm about to snag the new one.


ockham ( ) posted Mon, 24 March 2003 at 4:57 PM

Good. Tell me if it seems to work all right. It looks like there's a "hitch" just after the top of each bounce; if I can't solve that with mathematics, you can probably cut a keyframe at that instant to smooth it out.

My python page
My ShareCG freebies


Quoll ( ) posted Wed, 26 March 2003 at 2:49 AM

The bouncing looks too mechanical to me. Things in real life don't bounce at mathematically exact times and heights. Maybe use the script for blocking the animation but then try varying the keyframes a bit to make it look more natural. Also, some squash and stretch on that ball would help a lot, and you could try some ease in/out with speed.


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