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MoStu and trueConstraints
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MoStu and trueConstraints // Archive: Tech Forum
Post by Leif // Nov 5, 2006, 10:48pm
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Leif
Total Posts: 276
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I had an idea of constraining a joint to an animated object and record the keyframes. The scene is simple. A cone bounces on the ground with the joint constrained to it, and the other end joint constrained to the other stationary cone.
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Here is the simple example scene 2873 |
Post by Humdinger // Nov 6, 2006, 2:59am
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Humdinger
Total Posts: 319
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Hey Lief,
It's been awhile since i tried this but...
Setup your Mostu rig with all the nails you want etc.
Now take a cube and align it's center with the joint at the end of the mostu joint chain.
Now animate that object via keyframes or physical simulation.
Now after that is animated you can etract the animation path from the cube and save it...
Now use that path on the MoStu joint...select joint, then select saved animation path in TS.
Now when you play the animation, the joint will follow the path set by the cube...BUT..BUT
the rest of the rig will also move as determined by the path of the joint AND any nails you have set in Motion Studio. To the point that if the path takes the joint 'away' from a nialed joint the joint will only moves along the path as close as it can while still being constrained by the nailed joints in the Mostu rig.
Hope that made sense.
Hope it works too.
:) |
Post by Leif // Nov 6, 2006, 3:43am
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Leif
Total Posts: 276
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Thanks Humdinger, it certainly works!
The rest of the skeleton connected to the joint driven by the created path have a certain drag factor even if they are not nailed. The joint is constrained by the skeleton and the skeleton moves like through syrup, if the joint have to drag the skeleton. |
Post by LazeeGazzz // Nov 6, 2006, 5:49am
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LazeeGazzz
Total Posts: 55
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That's interesting stuff Leif. I'd tried out trueConstraints and quickly given up on it as a poor-man's IK system, but you seem to have hit upon some kind of physical simulation behaviour. Maybe I mis-judged it. These $$$ ckgf plugs are really powerful once you figure out how to actually use them (but there's the rub!). Any chance of a walk-through demo on how you acheived it?
As an aside; I know you've done some work with ClothMotion before. Did you figure out what the 'r' setting on the 'Collisions' tab means? I know 'h' modifies collision range but I've set 'r' = 0 through 1000 and it has no apparent impact. Any thoughts/guesses however vague would be valuable. Thanks. |
Post by Leif // Nov 6, 2006, 2:12pm
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Leif
Total Posts: 276
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Thanks LazeeGazzz.
Concerning ClothMotion, yes i did figure out that.
The manual put me on the right track:Use Parameters,r,h
The size of the form of collision detection is able to be set up. The collision range is able to be adjusted by the h=value, in the case that the collision type is Polyh.
So I thought, then r must be used if the type is something else than Polyh.
Collision objects can be represented by proxy objects, this is what Type:Sphere,Cylinder,Box and plane is. Type Polyh uses the actual mesh of the collision object when simulating, and requires more calculations. The proxy objects are much quicker.
When using collision objects that are set to Sphere, Cylinder or Box, the parameters r and h is used to set the radius and height of the respective objects.
Collision object type = Polyh
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Collision object type = Sphere
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There is a hint of spheres and cylinders as collision objects in this mini tutorial http://ckgamefactory.hp.infoseek.co.jp/tsxe/tut03.html |
Post by LazeeGazzz // Nov 6, 2006, 7:48pm
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LazeeGazzz
Total Posts: 55
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I just tried it out and that's an excellent explanation Leif, thanks.
For clarification though; 'r' affects sphere and cylinder only. Box is setup like a sphere because all corners of a perfect cube are equidistant from its centre. (That's really weird isn't it, that you can deform the sphere but not the box which would more useful? I guess all of the 'Type' shapes are really just variations of collision spheres). 'h' affects polyh objects too; it inflates their shape to create a buffer zone which helps prevent cloth-breakthrough. Looking at your first image I can see that you already know that!:D
I'm really very interested in your trueConstraints scene. Can you elaborate on it for me? |
Post by Leif // Nov 6, 2006, 9:06pm
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Leif
Total Posts: 276
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A quick reply,
In the very simple scene I used to test the idea, the cone was simulated using normal tS physics. After simulation did I attach the first joint to the stationary cone and the end joint to the bouncing cone by using trueConstraints. The plugin has nothing to do with the physics simulation. I did not see any of the joints move when I scrubbed the frames back and forth, so I clicked on the record button for every frame of animation in MoStu, and then the end joint were driven by the bouncing cone. For step by step on how2 I can write it later today. Very uncomplicated. |
Post by Leif // Nov 6, 2006, 9:18pm
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Leif
Total Posts: 276
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Here is the scene with the trueConstraints still in place (I deleted the constraints in the first scene, in case someone did not have the plugin installed). Select the first or last joint and check it out in "trueConstraints Editor" window, click on the eyedropper icon and then click on the line which says "ON translate to"
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Post by LazeeGazzz // Nov 6, 2006, 9:43pm
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LazeeGazzz
Total Posts: 55
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I'm very familiar with MoStu but not tCon so maybe I'm missing something obvious here. I understand the concept of using paths/animated objects to drive an IK chain, what I don't see is where trueConstraints comes into the equation. You are running 2 animation plugins simultaneously. The cone-weight could drive the MoStu chain directly. Why use tCon?:confused: |
Post by Leif // Nov 6, 2006, 10:22pm
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Leif
Total Posts: 276
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The simple reason is that I did not think of attaching paths to joints until Humdinger so courteously informed me. Other than that, I simply like to doodle around with the plugins. :cool: |
Post by LazeeGazzz // Nov 7, 2006, 12:40am
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LazeeGazzz
Total Posts: 55
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I simply like to doodle around with the plugins. :cool:
Me too!:) I'm only making a pest of myself because you really stoked up my curiosity. I need to re-investigate trueConstraints as there is more to it than meets the eye. Thanks for taking the time to share & explain your discovery Leif. (Are you related to that other famous explorer, Leif Erikson ??) |
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