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Grow / Shrink with pose slider


trajcedrv

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I have tiny - weeny problem...

 

I know that this is not a bug, it is a feature (which I have been using quite often - my teeth animation on the last animation contest is using this feature)

 

I have made and attached a little comic strip with the explanation...

 

This is the problem: I want to seriously reconfigure my character with the pose (Think Hulk - like transformation, which I want to show more than once in the animation)

 

Reconfiguration includes growing of some bones (and body parts around them) and their children bones, and also shrinking of the other bones (and their respective children)... Also, I will do quite a lot of CP pushing within that pose...

 

Now please look at the picture and I will continue in the next post... ;-D

post-43-1121553048.jpg

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Is there a way to make this in a pose in a sense that it can be done in the modeling window - with Ctrl - clicking of the scale manipulator... (I've tried - it doesn't work), so that short (ened) leg of Thom stays that way, even when animated...

 

I hope that I have been clear in my explanation, and I also hope that I have missed some really simple solution...

 

I wouldn't like to use expressions on every bone in the characters body (To be quite honest, I think that math which is necessary for that undertaking is waaay beyond me ;-D)

 

Any ideas, anyone ?!?

 

 

... please...

 

 

Drvarceto

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You have encountered a FUNDAMENTAL problem with squashing children by scaling thier parent: When you change the angle of the child, it continues to be squashed along the same PARENT axis, and hence "changes shape".

You must use expressions, or some other rigging trick to circumvent this. Sorry for the bad news.

 

Ben

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If you check out the rig I put in "Squetchy Thom", it would probably help.

 

The way around the bone rotation modifying the children bones is to make an IK/FK setup like you would normally, put some nulls (as an example, an arm) at say the shoulder, elbow, wrist and end of the hand, add bones that aren't part of the kinematic chain that are assigned to the CP's and have them "translate to" and "aim at" with "scale to reach" (on the Z axis) the nulls as needed. Then, make a percentage pose for each bone in the kinematic chain, scaling larger than you need at 100% (I used 400%) and as small as you need at -100% (I used 25%)...the important part is to scale the bones the same percentage on all axes. Next, make a pose that scales the kinematic chain's bicep bone as large as you need using the base slider you just made and scale the forearm bone exactly the same amount in the negative direction using its' base slider. Do the same thing for the kinematic chain's forearm, scaling the kinematic hand to the negative. Lastly, make a pose slider for the arm where the second set of sliders you made for the bicep and forearm are set to 100% at 100% and -100% at -100%.

 

What this does is, the nulls will move whenever you scale the kinematic chain bones, which in turn scales the geometry bones (on the Z axis if the "scale to reach" is set to Z axis only). For the squetch, you just put the expression "Transform.Scale.X=1/Sqrt(..|Z)" on the X axis and "Transform.Scale.Y=1/Sqrt(..|Z)" on the Y axis of each geometry bone. You can also just grab one of the nulls and squetch it any way you like, but the IK/FK control bones won't work right if you do.

 

 

 

Hope this helps.

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itsjustme, It does help, though it seems to be more work that I've anticipated...

 

If I can, I will try to trick that effect... if I get to animate that thing...

 

Anyway, I'll save your post and use the fomulae when needed...

 

 

Drvarceto

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