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Bones and hinges
About Truespace Archives
These pages are a copy of the official truespace forums prior to their removal somewhere around 2011.
They are retained here for archive purposes only.
Bones and hinges // Roundtable
Post by Paul Boland // Oct 30, 2007, 9:54am
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Paul Boland
Total Posts: 383
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Hi Folks.
Not sure if this is the right forum to post this...
I'm working on a 3D model in TrueSpace which I'm planning to rig with the new bones in 7.51. However, there is a part of the model that isn't directly organic, it's not to bend and deform, so I need to link this to the model using a hinge.
Now, this is the exact same problem I've had with TrueSpace since version 5 when I first got into character creation. Bones and hinges don't like eachother. I was hoping this would be different for TrueSpace 7.51 but my test scenes have failed.
I created three cubes which I hinged together. I then create a cylinder and placed a bone in it so it could bend. All was well till I tried to connect the two things together. Using the Attach Object To Bone, I tried to connect the base cube to the top of the cylinder. When I moved the cylinder, the base cube was connected to it, but the two cubes hinged to the base cube had lost their hinges.
So how do I achieve this? How do I mix bones and hinges in a single model? Or, does anyone have any ideas on how to create a bone structure which acts like a hinge in that it won't deform the part of the object that it's connected to as a bone would? |
Post by jamesmc // Oct 30, 2007, 10:16am
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jamesmc
Total Posts: 2566
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There's probably a better way than I've tried. I got my first clue from Jack Edwards on using attach "object to bone."
What I would guess is that you would make your object, one and skin it. Then, make separate objects, each with their own boning and skinning.
Then you would attach them to your main object.
Not sure if that makes sense.
The way I figure it, if one doesn't want to make some heavy poly object, making separate objects with some "dynamic" coverings might be the way to go.
i.e. putting some cloth or some other covering to disguise the mechanisms of using a skeleton for animation. |
Post by frootee // Oct 30, 2007, 10:27am
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frootee
Total Posts: 2667
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sounds like the attach to bone tool is the way to go.
You can take a rigged character, say, crazybob, and attach a coffee cup to his hand using the attach to bone tool.
Crazybob will deform as expected, and the coffee cup will move with the attached bone, but will not deform.
There are a couple examples here:
http://forums1.caligari.com/truespace/showthread.php?t=3815
HTH!
Froo |
Post by opiejuan // Oct 30, 2007, 11:10am
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opiejuan
Total Posts: 120
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Paul
Need more info. You say the 3 cubes are 'hinged' together. Are they just glued as siblings with the axis moved to where you want them to hinge? Or are you saying they are set up with trueSpace's IK system? Then when you attach them to the boned (deformable) cylinder you lose the ability to drill down in the hyarchy of the glued objects or manipulate the 'IK' setup? |
Post by Paul Boland // Oct 31, 2007, 10:17am
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Paul Boland
Total Posts: 383
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Thanks very much for the input so far, it is appreciated.
JamesMC, you've totally lost me, mate! Could you tone it down a bit, sorry.
Frootee, that works great if you want to attach a single object with no moving parts. It's when attaching a moveable object that it messes up.
Opiejuan, thanks for the help. Let me clear up this for you. I link the three cubes together using two IK hinge joints. This allows the cubes to twist on the hinge without any deformation. However, if I use Attach To Bone to attach the base cube to a boned object, the base cube will be connected, but the IK hinge joint between it and the two other cubes are lost.
If anyone can tell me how to do this I'd be very grateful. Or, if anyone can show me how to achieve this type of rig using just bones, again, I'd very much appreciate it. |
Post by opiejuan // Oct 31, 2007, 10:58am
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opiejuan
Total Posts: 120
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Thanks very much for the input so far, it is appreciated.
JamesMC, you've totally lost me, mate! Could you tone it down a bit, sorry.
Frootee, that works great if you want to attach a single object with no moving parts. It's when attaching a moveable object that it messes up.
Opiejuan, thanks for the help. Let me clear up this for you. I link the three cubes together using two IK hinge joints. This allows the cubes to twist on the hinge without any deformation. However, if I use Attach To Bone to attach the base cube to a boned object, the base cube will be connected, but the IK hinge joint between it and the two other cubes are lost.
If anyone can tell me how to do this I'd be very grateful. Or, if anyone can show me how to achieve this type of rig using just bones, again, I'd very much appreciate it.
Ok...I hope I can explain this well. If it doesn't make sense, then let me know and I'll try to do some screen grabs tonight at home.
First...to my knowledge bones and the actual IK system in trueSpace cannot co-exist. BUT! Instead of using the formal IK links and hinges, you should be able to do this manually ( FK ..as in Forward Kenematics ) and get the effect you are looking for.
Lets start off with the 3 cubes but without ANY of the IK stuff attached...just plain old cubes. Choose which cube will be the cube that will be attached to the bone in the cylinder and select it. Now click the 'Glue as Sibling' tool and click on the next cube in the stack.
So we have 2 cubes glued up and one to go. With the glued cubes selected, press the down arrow key on the keyboard to step down in the hierarchy. If the base cube is highlighted, press the left or right arrow key on the keyboard so the newly added cube is selected. Again click the glue as sibling tool and add the final cube now. If you hit the up arrow key a time or 2 you should have the whole group of 3 selected. If you are not used to using the arrow keys to move through the hierarchy this way, take a few moments to see what it takes to reach each cube individually and the lower group(s). It'll become second nature really quick, don't worry.
Before you set ANY animation keys OR attach the base cube to the bone, you will need to change the position of the axisses? axii? hmmm...the axis of each cube and/or groups or sub-groups so they will 'hinge' along the edge you want. Again, play with the glued up group a bit to see how to navigate using the arrow keys to manually rotate the cube(s).
What you will be doing is manually working the hierarchy instead of letting tS's IK do the work. There are advantages to both ways, but I prefer to do it the manual (FK) way as it is MUCH more precise and easy to work without surprises. But that's just me.
When you are ready to attach the cube stack to the cylinder, I would save the scene and try it different ways to see how it functions....1st move down the cube stack hierarchy to the 'base' cube and attach it to the bone. By default the rest of the hierarchy get's attached intact and is animatable. Also try attaching the whole cube stack to the bone and see what limitations or...um...'Features' are presented to you there:)
Long winded, but I hope it helps |
Post by Paul Boland // Oct 31, 2007, 11:15am
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Paul Boland
Total Posts: 383
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Thanks very much, Opiejuan. I'll mess around with this tonight and see if I can get the results I want. Very much appreciate this, thanks! |
Post by opiejuan // Oct 31, 2007, 11:23am
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opiejuan
Total Posts: 120
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My pleasure :)
Just make sure you have each axis changed before you set any animation keyframes, becuase tS will not let you change them after a keyframe is set.
Have Fun! |
Post by opiejuan // Nov 1, 2007, 2:05am
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opiejuan
Total Posts: 120
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I got home yesterday and tried out my own suggestion since it has been a few years since I last tried this approach. I have to admit, my memory isn't as sharp as I thought. What I explained yesterday does work...but it's not as functional as I thought in tS6.0. It's just a workaround at best and has some major quirks that can drive a crazy man sane :)
I hope in 7.5 it works better for what you need. |
Post by Paul Boland // Nov 1, 2007, 10:09am
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Paul Boland
Total Posts: 383
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Opiejuan, it didn't work, mate! LOL! I followed your instructions exactly, three times, and when I bend the cylinder after attaching the base cube to it, the base cube is connected to the cylinder, but the other two cubes are no longer connected to the base cube.
Any thoughts? |
Post by opiejuan // Nov 1, 2007, 8:37pm
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opiejuan
Total Posts: 120
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First let me apologize for an error. I said to 'glue as sibling' and it should have been 'glue as child'. Also there are some important guidelines to this workaround. So if you will allow me to make up for my error, please go to the tutorial page on my site (http://www.opiejuan.com)and see if this will help you. I only had a couple of hours to work it all out, so forgive if it's hard to follow. I'll try and update it with more detail this weekend ifyou need. Let me know. |
Post by Paul Boland // Nov 2, 2007, 10:23am
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Paul Boland
Total Posts: 383
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Opiejuan, thanks very much for taking the time to do this for me. However, I'm heading off for a few days break (going to spend some time with a giant mouse in Orlando Florida :D), so I haven't got time to dive into this now. But I have saved the tutorial page and movie to my computer and when I get back, I will definately take a look at it. But from what I can see, I think you've hit the nail on the head. Really appreciate this!
Thanks again. |
Post by opiejuan // Nov 2, 2007, 11:07am
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opiejuan
Total Posts: 120
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No problem. Have a good time!
Give Minnie Mouse a big ol' hung while yer there :) |
Post by Paul Boland // Nov 23, 2007, 9:16am
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Paul Boland
Total Posts: 383
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Opiejuan, just want to let you know that I haven't forgotten your tutorial. I haven't had time to look at it yet, but will do over the next few days. But as I said above, from what I can tell from looking at your tutorials screenshots, I think you've hit the nail on the head. Will let you know how things go. Thanks again. |
Post by Paul Boland // Dec 3, 2007, 9:45am
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Paul Boland
Total Posts: 383
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Opiejuan, BINGO!!! Your tutorial works perfect and gives the results I want. Very much appreciate it. Sorry I took so long to get back to you on this. |
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