Creating the spline IK

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At the heart of Sply,

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Ike

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is a curve

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and the tool will create one for you automatically,

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but I prefer to build my own

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just so I know exactly how it's constructed. And what CVS I have to work with.

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Go to the create curve tools,

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edit point curve tool and open the options.

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We want this set to three

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cubic. So we get a softer curve

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now holding V click next to each joint in the spine to create a series of points

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when done press enter to finish the curve

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and there it is our curve.

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Let's rename it to spine curve

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and go back.

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Now we have the curve, we can create our Spline I

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handle,

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go to skeleton,

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create ICA blind handle and open the options,

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just reset this.

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So these are the basic options.

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We already have a curve so we can disable this.

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We also don't want the curve parenting to the joints

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so we can disable this too.

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Now select the root joint

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and then the end joint

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and then finally the curve

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and there we have our IK blind handle,

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just rename this.

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So unlike normal IK, you don't animate the main handle,

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you deform the curve instead to control the joint's movement.

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You see

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if I select a CV and move it,

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the joints follow.

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So we get a nicer more natural movement,

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I'll bring back the control joints now

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and all we are going to do is bind them to the spine curve.

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The default options are fine.

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Just use selected joints as the bind to option,

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we can now use the controls to move the control joints

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which in turn are deforming the curve.

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This curve is then now changing the shape of our main spine control joints.

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Let's bring back the model so we can see him deforming.

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Ah OK. Something's not right here.

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Ah So it seems I created the IK Spline on the FK joints instead of the IK joints.

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OK. I've just gone back and rebuilt it using the right joint chain this time.

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Now we can adjust the controls and the spine deforms with them.

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It may be that an area doesn't deform how you would like sort of

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like here where the head is tilting as the top of the body moves.

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Because we use the skin cluster on the curve,

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we can edit the weight values to adjust how it deforms.

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Let's show the curve

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and select some of the upper cvs.

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The top 3 may be

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now go to Windows General editors, component editor.

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So we can see here under the smooth skins tab

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the weight values.

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Let's change them So they are fully weighted to the upper spine control joint.

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So set these to one

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that's updated now.

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So it's not perfect. So it needs more tweaking and adjusting,

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but the shoulders are now more level.