View Full Version : Motion Designer

12-30-2003, 08:40 AM
I find motion designer impossible to use if I want it to detect collisions.

Do you need to have the two materials that you want to collide as searate models? On separate layers? Or will just as separate materials do? Because it seems that no mater how I alter the setings, the material still goes through my model's legs.

12-30-2003, 09:12 AM
Do you have one object set as target and the other set as collision?

12-30-2003, 11:29 AM
I guess that must be the problem. It is a single mesh model, I was trying to do it with fixed and active materials. I'll break the model up and try again. Thanks.

12-30-2003, 11:58 AM
I'm no expert on motion designer by any means. But if it's all one model, have you made sure self collision is on?

12-30-2003, 12:01 PM
Yes, I did have self collision on, and by turning up the skin thickness on the material (legs) I wanted the fabric to collide against, I got some strange results. Ultimately, the cloth either flew up in the air, or it would just keep on going right through the legs.

12-31-2003, 02:04 AM
Okay, so I've broken the model into a skirt and the body and legs. Now the problem is, how do I attach both the meshes to the bones? I can only get one mesh attached.

Is it possible to have two models atached to one set of bones animation?

12-31-2003, 03:14 AM
Select the "boneless" object.
Press "shift-b" to get into the bone mode.
Hit "p" to get the bone properties.
On top of the panel there's a pulldown menu wich says "Use bones from"... There you select the mesh with the bones.
Voila. It will now be deformed by the bones of the other object. All the weight maps will be respected too.

12-31-2003, 03:35 AM
Great. Thanks Pixelranger, I've got that done.

Now, I've actually tried this a while back and couldn't get it to work. I've followed tutorials and RTFM and everything (plus asking here), and I'm beginning to doubt if Motion Designer is up to the task at had. There appear to be no settings on earth that will keep the dress on the correct side of her legs. PLEASE, someone who knows about this, tell me if what I am trying to do is possible or if I should try a different tack.

Thanks in advance.

http://www.3dgamesforkids.com/pictures/spydress.jpg :)

12-31-2003, 03:42 AM
Try pumping up the calculation resolution to about 100.
Also try to increase the collision objects' skin thickness in the md settings panel. Are you using a poly stand-in for collision detection or are you using sds-legs for the skirt to collide with?

01-01-2004, 01:00 AM
Thanks again Pixelranger,

Boosting the calculate resolution only succeeded in slowing things down. I bumped it up all the way to 50000.

Uping the skin thickness of the collision object eventually makes the dress explode up in the air, but it still goes through the model.

The way I've set it up is, I broke the model into two parts: the dress and the rest of the model. I set the the top row of polygons on the dress to fixed to stop it from blowing away. I gave both objects the same set of bones and animations and put them in the same position. I set the body object to collision, and the dress to target.

It's not even close to working, and I'm beginnning to doubt Motion Designer is able to cut the mustard. This model does karate moves, and I can't even get the dress to stay out of her legs when she's hardly moving. Has anyone seen a working example of what I'm trying to do?

If Motion Designer can't handle this kind of animation ,does anyone know a programthat can? Or should I be using bone or point animation for this project?

01-01-2004, 06:04 AM
Happy new year !!!!!

Try increasing the "Skin Thickness" setting for her legs. Im sure that will sort it.

Rob T

Ive just read the post above and youve tried that already...you say that it blows the skirt up in the air, maybe youve crancked up the setting to much.. what height is your girl?

The setting for skin thickness is measured in meters..so you might only need to move it up by 0.01

Also.....have you tried the sub structure setting..might help!!!

01-01-2004, 06:05 AM
Well, You want to have your dress and legs slightly higher poly I think. Use Parts on your skirt object, selecting just the bits which will swish about, and use a object which is just the lower half of the body (using the bones of your woman to control it)as a collision object. Use a nurbs mesh if you can, and you can up the detail of it a lot easier. If you have a lot of big polys in the skirt/legs, it's going to be a lot harder for MD to sort out the collisions. You need to have a nice mesh with an even distribution of polys, not some tiny ones in some places and huge polys in others. It's question of balance. I've got reasonable results, you just need a bit of practice. The way your mesh is built is much more important than the calculation resolution.

Also, use the stretch limit value (set at about 10%) rather than upping the spring value as this tends to make things jiggle. Apply more viscosity and this will calm things down too.

01-01-2004, 09:12 AM
Thank you Dodgy. There is one problem with that though. This is a game model, and I don't want any more polies in her. She's at 2300 as it is. After bumping the poly count in the legs and skirt and animating, how would I strip the polies back off again? There are 360 frames of animation.


01-01-2004, 10:07 AM
You can use a higher density mesh for calculation purposes, save the motion as an mdd file in motion designer. Then you can reduce the polys and apply that mdd file to the lo rez version for the game model.

01-01-2004, 12:07 PM
I tried that, but the dress still goes throught the legs. It does seem to be ever so slightly better though. Someone should make a "keep the material on the right side of the collision object at all times" button for Motion Designer.

Any other ideas? Also, I've never actually seen a model made with lightwave that uses motion designer for a dress like this. Has it ever been successfully done?

01-01-2004, 12:43 PM
check here

01-01-2004, 05:25 PM
If you're doing it for in game, are you using morph targets (in the game not in LW)? Otherwise won't your team have to use their own dynamics system to do this? In which case it shouldn't matter what MD does, it's down to your dynamics team.... or will you be using the settings from MD to drive the engine's dynamics?

01-01-2004, 07:44 PM
Here's a general list of tips that might help out some with MD:

This is a bit of a progression of how Skelleton Man does an MD
character with a coat or apron etc.

MOST IMPORTANT NOTE - build to true life scale. A man should be
approx 1.84 meters tall. If he is huge or tiny, you MD values will
have no meaning since the are based on meters etc.

First you have a character model. (I tend not to use layers fo
rhtese purposes as separate objects work better. This is for
object replacement purposes)

Object 01 - The character, complete with skelegons (MD will not
like this character so it's really just to create and test bones.
usually I don't btoher putting all the morphs and what not in it.)

Load this character into layout and convert skelegons to bones.
Now he is ready to anime.

Object 02 - The same character. This is basically the same model
but with no skelegons. This is the one that will actually be used in
the final scene and for rendering.

Go to object 01 in Layout and do a replace object with object 02.
He looks the same, but now the model doesn't contain
skelegons. No more point problem.

Object 03 - The apron or coat etc. (a subdivision object) I tend
not to use layers for this either as I have multiple versions. For
this doc we call them:

Object 04 - The apron frozen at patch level 2

Object 05 - The apron frozen at patch level 3

as so on... remember that very low res meshes tend to be bad
for cloth objects. Collision is based on points on the target object
hitting polys on the collision object. In a very low res cloth, two
points can easily pass right over an edge on the collision object.
The guys arm could be halfway through the coat before the two
points actually hit something.

Now - Load Object 03 into layout and parent it to Object 02. If
necessary, let object 03 use bones from object 02 (if your clothes
have any "fixed" surfaces this will be necessary.)

Open the MD controller. Activate both objects. Object 02, the guy
is collision, Object 03, the apron is target. Even if the base object
is too low res, it's good for speed and to get settings right.

Let's do a simple environment first. Gravity = -1y... that's it.

Now go to surfaces. The surface of the guy shouldn't matter. If he
is built to scale the default skin thickness should work. If you
want you can add friction to him.

The cloth. A good place to start is cotton thick preset. A few
things I like to change: More weight can sometimes be good for a
good cloth effect. Lower viscosity values also make it less rubbery
and more like cloth. Resistance can be set to 2... the makes the
cloth a little stronger such that it won't want to move all the time.
With resistance and more weight you can actually get cloth to
settle on something and stop moving.

Another thing I like is to lower parallel resistance. Cloth is
somewhat like paper in that it can be held up on air when parallel
to the ground. This is what helped the coat on the guy in my new
teaser trailer on the site. (take a look if you don't remember)

Sub structure can also help give MD the idea of more res to your
object. 1000 is a good value.

That should do it. Hit the start button and see what happens.
More than likely it will be very fast (If your initial object is low res)
and work well. The low res object may cut through the guy in
places but don't worry about that.

If you like the result. Replace the Object 03 with with 04 or 05
depending on how much detail and how much wrinkling you
want. Run it again. With more resolution, the cloth should no
longer cut through. More points to collide with.

Note to remember:

If you use subdiv objects, MD is calcualting based on the shape of
the object *before* TAB was hit. You can imagine if you make a
six sided arm, it may look round at subdiv level 3, but MD is
calculating based on the original siz sided object and your cloth
will take this shape when it falls.

What I do in this case is freeze the collision character object at
level 1 - it it still low res, but takes the shape of the div version.
Use this for collision. You can also make it one surface to speed
things up.

If you want even more accuracy, freeze the character at level
two. Your cloth make take longer, but it will really start to rival
the best CG cloth you have seen anywhere.

If you have movie to watch or it's time for bed, try freezing the
character at level 2 and the cloth at level 4. This will look amazing.

I have done all my work on a P 550 machine. Usually I can stand
to watch it calculate the lower res stuff and I'm not all that
patient. If it is taking longer than 2 seconds per frame to
calculate on the lower res stuff, something is wrong.

Hope this helps.

01-02-2004, 03:22 AM
Hey, thank you to everyone who has replied! I am finally, after another grueling day, getting some results. The links and info posted was all very helpful.

The legs still go through the dress in places, and it seems unavoidable for a low poly model. If I use subpatched models to get it so that the dress doesn't go through anywhere, then try to replace them with the low poly verson, the problem just comes back. I think it only works the other way around; use the lowest density mesh posible to get the animation right ( saves on calculating time) then replace it with an even higher poly mesh for rendering. In this case I'm trying to keep the poly count low.

After a break, I'm going to try fattening the legs on the test model, then replace them with the normal ones after the calculating is complete. Increasing the skin width of the collision object doesn't work effectively because the dress is too close to the skin. So if I faten them both up a bit hopefully I'll get an animation that will look good.

@Dodgy, this is an amatuer project. My very first game character, in fact. Almost my first model ever. I don't have a team of dynamics experts standing by to take over from me :) It's more a learning experience so I can do it myself. It will simply be point animated in engine.

Thanks again, I'll post some shots of it for some constructive criticism after I've got it at least looking half good.

01-02-2004, 10:25 AM
Erm, one more thing, how do you edit the points on individual keyframes in Layout? I can't touch the geometry there.

01-02-2004, 11:34 AM
You can't at the moment without this plugin:


A (very few!) instructions:


Basically, you add it as a plugin, then add the displacement plugin FI's minimodrv to your object. then by opening the generic plugin FI's minimo, you can move/scale/rotate points and keyframe them. For a bit more explanation try here: