View Full Version : rigging a 2 way spline

01 January 2011, 03:28 PM
okay so havent seen a post about this, and would apriciate any advice on this.

So i have a fully functional rig that iv made for my gorilla style character, thats' spline's base is where the chest normally is. I want the front control to lead as he walks on all 4s mainly. but also needs to have the option for the back control to bring the whole body down when the character sits down.

The rig also has a middle control, controlling a cluster which allows the spine to rotate and translate from the middle. This control will need to be parented to the top control when walking on all 4s and the bottom control when sitting down. So i parent constrained it to both, one at a time and it created a blendnode, which allowed me to weight it from one to the other which was fine, allowing me to switch the middle controls parent from the top to bottom control,but!

But when he sits down you obviously want the whole upper body to follow the bottom control, so the top control also needs to be parented to the bottom control on a blendweight which it was and followed, but soon as the weight is switched to the top. The top moves and then when you move the bottom to follow, the top freaks out. And i havent been able to figure out to get both control to switch in harmony.
Any advice on a solution to this would be great, the main problem is i wont have time to re-rig a whole new spine in the other direction. as our project is quite big and iv got lots of other modelling and texturing to do. so im looking for a control baised solution not a re rigging solution. If it cant be done no worries il swap the hierachy around and have two copys of the rig. but would be more practical if could have a ikfk style switch for the spine controls.

thanks matt b

01 January 2011, 02:11 AM
that sounds like it gets double transformation. But, one thing I wonder is, how the blendWeight took place in your situation? Normallly, if I parent constraint anyting over to something that has already been constrainted, another weight will just appear in the parent constraint node so I can adjust them both.

for the back i have 3 ctrls. top, middle, bottom

The top control is parent constraint to the bottom ctrl and the main ctrl. allow you to switch between following the bottom of the spline or the master ctrl that control the whole character position.

The middle control is always be the one I put in between the two top and bottom by parent constraint it to both having equal weight so it sits right in the middle of the two.

The bottom control parent to the root ctrl(the one control the root of the skeleton which is right above the hip) and the master control. So, you can choose the bottom ctrl to follow the root control(which is control the whole body shape, including the hip.) or just stays where it is and just follow the main position of the character.

hope this helps, excuse my english.

01 January 2011, 06:20 AM
hey! if u need all the spine controls to follow when your character is waking on all fours u, might need to constrain the pelvis control to the chest to.. and in a normal case u want the chest to follow the pelvis..if am not wrong.

i hope it will help you.u just have to constrain the pelvis to the chest control and again vice versa and need to switch between the constrains. u just need to play with the constraints...

parent constrain the chest control to the pelvis control and also constrain the pelvis control to the chest.
so wen u want the pelvis to follow the chest just turn off the constrain weight on the chest control...the pelvis will follow the chest. and when u want the chest to follow the pelvis , turn off the constrain weight on the pelvis.

The best option would be to create a switch for that. just keep swapping the constraints. i hope this will help.

01 January 2011, 04:34 PM
thanks for both replying so quick didnt expect as quick response. anyways havent tried them yet as im weighting my bap character at the moment. but il try these methods soon as im done. havent weighted characters for a while so getting back into the swing of it.

I think i tried your method debalin already in a seperate scene, with 3 shapes as a test. cube for the top ctrl triangle for the middle and torus for the bottom and constrained them vs versa and turned of the corresponding blendweight for which end i wanted to be in control. so for example id turn off the blend weight on the top and turn on the middle and bottom one so they follow the top but when i animate the top the middle follows and the bottom. but everytime i try position and animate the bottom somewhere else it snaps back to the postion it was in. difficult to describe i may have to post a video on my blog and link you to it if i cant solve the problem soon

anyways thanks again guys il try out both methods and get back to you asap on result.

cheers mb

02 February 2011, 11:32 AM
hey guys so i tried out the techniques that you guys mentioned but still got the snapping problem, i think im either doing it wrong or it just doesn't work with the spine ive made. I think it maybe because ive made a reverse spine. thanks for the advice anyways guys, il try come back to the rig when i get some more time. cheers matt b

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