Snapping model parts question

[detbear]

Here's a Noob question for you guys that I missed on somewhere down the road.

 

Is it possible to snap a bone to a CP's position?

 

If so, how might that be accomplished?

 

William

[robcat2075]

Here's a Noob question for you guys that I missed on somewhere down the road.

 

Is it possible to snap a bone to a CP's position?

 

If so, how might that be accomplished?

 

William

 

In the modeling window? No (?), aside from manually copying the XYZ values of the CP to a bone's

 

However there is a "Group" constraint that will translate a bone to the center of a group, which would be the same as a CP if the group was only one CP.

 

A classic use of this is to make buttons follow simulated cloth.

[detbear]

In that case, a great new feature suggestion would be a "Make bone at CP". That would be very cool.

[robcat2075]

In that case, a great new feature suggestion would be a "Make bone at CP". That would be very cool.

 

You can export the model from a chor after you turn that constraint on. That will save a copy with the bone moved.

 

What are you doing that needs this?

[detbear]

So what you're saying is that if I export the model, the bones won't need to have the constraint in order to remain in that position?

 

If so.....that could be very interesting indeed.

[robcat2075]

So what you're saying is that if I export the model, the bones won't need to have the constraint in order to remain in that position?

 

If you need the bone to follow a moving CP in animation then you need the constraint.

 

If you just need to adjust the bone to the CP once, then exporting will work.

[detbear]

I looked at that constraint method and even though it will work, I think the task is rather daunting on a larger scale. A function to snap a bone to a specific cp's position within the modeling window in "Bones Mode" is what would be ideal:

 

1.select bone

2.right click and select "snap to CP"

3.Left click on desired CP

 

Result......The bone is re-positioned at the x,y,z position of the cp.

 

 

Example....if I want a bone at every cp on a spline ring, then positioning this by hand can be a lot of tedious work.

[Xtaz]

You can do it using expressions ...

You must create a group containing only one cp.. then translate bone to its pivot through expression ...

check it here

[robcat2075]

A function to snap a bone to a specific cp's position within the modeling window in "Bones Mode" is what would be ideal:

 

1.select bone

2.right click and select "snap to CP"

3.Left click on desired CP

 

Result......The bone is re-positioned at the x,y,z position of the cp.

 

That probably wouldn't be hard for Steffen to add. But... what orients the bone? A CP is just a point in space with no direction to give to a bone.

 

Does the bone just retain its original orientation?

[detbear]

Yes...the bone would basically maintain it's length and orientation.....and just have its origin/ base placed on the exact point as the CP..... You would want the ability to rotate the orientation and even translate the bone later down the road. This function would just be for initial placement of the Bone. Even dreaming a bit more.....it would be helpful to do this also in an action window too.

 

Basically the cp's in this case would act as a pattern to place the bones at specific points in x,y,z space.

 

There's a purpose for this....although it seems ludicrous at present. When I get something operational and working, I'll show you.....but I'm working through it by hand, so it's at a snail's pace.

 

I realize Steffen is booked solid at the moment. I'm working on this by hand and just wishing a function like this existed.

[robcat2075]

There's a purpose for this....although it seems ludicrous at present. When I get something operational and working, I'll show you.....but I'm working through it by hand, so it's at a snail's pace.

 

Is this for a modifiable character? I think the Group constraint and export from Chor would work well for that.

[detbear]

There's a purpose for this....although it seems ludicrous at present. When I get something operational and working, I'll show you.....but I'm working through it by hand, so it's at a snail's pace.

 

Is this for a modifiable character? I think the Group constraint and export from Chor would work well for that.

 

 

I'm no expert with the group constraint, so I could be off base. When I looked at how it worked, it was based on selecting groups from a very small drop window. If you have 100 or more cp's set up in groups, its painful to select the correct group for each bone. Would it work.....I think yes. But that would be a very long process. I may not be seeing the correct way to utilize the group constraint, but it would be very difficult unless you only had a few groups in that list.

[detbear]

Is there a tutorial or example somewhere on ther forums here on how to best use the group constraint? I'd like to find out a bit more about it. I've seen it for a long time on the constraints list, but haven't messed with it at all.

[robcat2075]

I'm actually trying this notion for the first time now... this will take a bit of R&D...

[detbear]

Is there a tutorial or example somewhere on ther forums here on how to best use the group constraint? I'd like to find out a bit more about it. I've seen it for a long time on the constraints list, but haven't messed with it at all.

 

 

It's more than a "Notion."

[robcat2075]

Here's what works so far...

 

StretchableCharacterConceptH250.mov

[mtpeak2]

Did you try hitting the spacebar, to refresh the screen, to get the aim at contraints to readjust?

[mtpeak2]

You may want to try turning the pose on first, before modifying the mesh.

[robcat2075]

Did you try hitting the spacebar, to refresh the screen, to get the aim at contraints to readjust?

 

that also works, however I'm still having the problem of the bone orientation not surviving the export of the chor as a model.

[detbear]

Did you try hitting the spacebar, to refresh the screen, to get the aim at contraints to readjust?

 

that also works, however I'm still having the problem of the bone orientation not surviving the export of the chor as a model.

 

 

Robert.... That looks like a very promising constraint Application. The hurdle in my case is that when the mesh change does take place, it needs to go to specific locations and the bones need to be there as well.

 

However...this constraint does hold some good application if it turns out to work like you are trying to get it to.

[robcat2075]

The hurdle in my case is that when the mesh change does take place, it needs to go to specific locations and the bones need to be there as well.

 

Explain that more.

[Gerry]

It also looked like the bones that snapped into place once you've advanced a few frames, were misplaced in exactly the same way in the exported model. Seems like you should investigate why they weren't in position on frame 0.

[mtpeak2]

Ok Robert, in the pose apply the aim at constraint first, then the group constraint with apply before action ON. This should export correctly.

[detbear]

The hurdle in my case is that when the mesh change does take place, it needs to go to specific locations and the bones need to be there as well.

 

Explain that more.

 

 

I'll have to show an example when I finish....stay tuned. The goal is to use a bone to place a cp in a apecific location....But in order to make that happen, the bone and cp must be synch'd up......This is why a "snap bone to cp's position" feature would be worth it.

[robcat2075]

The goal is to use a bone to place a cp in a apecific location.

 

That's what regular old assigning CPs to bones does. So, yes, I do await further explanation...

[mtpeak2]

Actually, the order of constraints doesn't matter, just turn ON apply before action on the group constraint.

[robcat2075]

What am i doing wrong here:

 

Trying to force keys with constraint results...

 

TryingToForce_Constraints.mov

 

Actually, the order of constraints doesn't matter, just turn ON apply before action on the group constraint.

 

I think I experimented with "before action" already, but I'll try some more.

[Gerry]

Help us, Robbie Wan Kenobi! You're our only hope!

[mtpeak2]

Here's a model that exports the bones correctly from a chor.

bone_snap_to_group.mdl

[mtpeak2]

This also works in an action, no need to export from the chor.

[robcat2075]

Here's a model that exports the bones correctly from a chor.

 

that does work! Problem solved!

[robcat2075]

Now the next layer is to figure out how to have the CPs attached to the bones beforehand and yet not create circular constraints.

[mtpeak2]

Assign cps after export.

[robcat2075]

Assign cps after export.

 

Well, the idea is you could have a generic character with these geometry bones preweighted and you could push and pull CPs to modify him. Then you could make the bones travel to fit the modified mesh, export it and run a rigger on it to finish it.

 

If you had to weight the CPs every time that would negate the advantages.

[mtpeak2]

This would be impossible. Though I modify existing models that are rigged all the time, with minimal adjusting of the weighting. I'll use the bones in bones mode, with the scale manipulators ON and the control key held down. You can still modify the mesh, but you don't want to change the key locations of the joints, that's where you want to use the bones.

 

That's why he's looking for a bone to snap to cp/group feature. Trying to do this in an action or chor would be impossible with cps already assigned.

[robcat2075]

"Impossible" just means it hasn't been figured out yet.

[mtpeak2]

Well, if you figure out a way around the circularity problems, you will need to figure out a way for the cps to not move with the bones once you move the cps (move cps, bones move to new location, cps follow the bones movement).

 

I would think creating a plugin to do this in the modelling window would be easier to figure out. Create groups with the same name as the bone you want to move, plugin copies pivot to the bones start position and the end position would be the start position of the next bone in the chain. If it's the last bone in the chain, the bones length and rotation remain the same or a group can be used.

[robcat2075]

What am i doing wrong here:

 

Trying to force keys with constraint results...

 

TryingToForce_Constraints.mov

 

Anyone know why the bones don't stay in place after keys with constraint results were forced on them? I ought to be able to turn the constraint off after that and have them remain in place. (post #27)

[itsjustme]

What am i doing wrong here:

 

Trying to force keys with constraint results...

 

TryingToForce_Constraints.mov

 

Anyone know why the bones don't stay in place after keys with constraint results were forced on them? I ought to be able to turn the constraint off after that and have them remain in place. (post #27)

 

Could you post the model, Robert?

[robcat2075]

Could you post the model, Robert?

 

Here's a PRJ

 

In the chor the POSE with the constraints is ON on frame 0 and keys forced there. At frame 5 the pose is turned OFF

 

Stretchable_rig_demo_10f_Pose_ON_then_OFF.prj