tIntro
to Maya's Set Driven Keys Tutorial (SDK)
by Wade Ryer
Set Driven Keys (SDK) are essential
to making the most of Maya as an animation package.
SDK's are a basic function in which the user may set
a conditional keyframe that relies on another keyframe to
establish it's own properties. Simply put, if A=W and B=X, then A=Y
and B=Z. “A”
is the "Driver," and “B” is the "Driven.” Depending on the properties set to A, B will respond in different
ways. This can
be extremely useful for rigging purposes.
The following example demonstrates
how this works in a basic muscle flex. This technique may
be used for infinite other uses.
Download the following file:
sdk_demo1.mb
This file contains 2 polycylinders (1 flexed arm and 1 straight
arm) and a 3 joint IK bone.
Set the blend shapes for the
arm. Select the
flexed arm, hold Shift and select the relaxed arm and select
Deform-> Create Blend Shape.
The channel box should now have an input for the new
blend shape.
Do a simple bind to get the geometry
attached to the bone. Select the arm and select joint1, then
select Skin->Smooth Bind.
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Select the blendShape1 and select
Animate->Set Driven Key->Set ->(open window
icon). The
Set Driven Key window should open. Highlight the blendShape1 and highlight the arm_flexed
to the right.
This will be the driven object.
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Click for detail
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Minimize the SDK window and select
the forearm bone, or joint2 (turn off select object
by geometry may help).
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The next step is to connect the
arm rotation to the shape of the flexed arm so that
every time the arm bends there is a nice flex. Restore
the SDK window, and while the joint2 is selected, click
the "Load Driver" button.
This loads the selected joint2 into the driven
column. Now select the rotate Z for the joint2
driving attribute.
Press Key.
This sets the initial key.
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Next, select joint2 (the forearm),
and rotate it 90 degrees in the Z direction.
(It may be useful to turn the visibility of the
flexed arm in the layers).
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Select the blendShape1, and in
the channel box input “1”for the arm_flexed
attribute. This
should flex the arm.
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Finally,
go back to the SDK window and hit Key. This should set the last key. To test this, simply rotate the arm
in the Z direction and the arm should be mighty and
strong, flexing about like Hulk Hogan.
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You may download the final source
file here: sdk_demoFINAL.mb
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