Animation 2

 

Muscles and Joints

 

Muscles (Influence Objects) create further deformation on the skin geometry. A Muscle is underlying geometry – parented to a joint – that deforms the bound skin. The muscle geometry can enlarge or shrink the bound skin based on joint transformation, though it need not be limited to this only.

For Rigid Bound skin that kinks in a tight bend, Maya has a specific lattice called a Flexor.

 

Muscles (Influence Objects)

Along with Joints and Bones, Maya also has functionality for muscle emulation. As joints rotate about certain axes, Set Driven Keys can be set for enlarging or distending surface geometry.

Skin -> Edit Smooth Skin -> Add Influence.

Muscles can only be assigned to Smooth Bound surfaces. Polygons, NURBS, Locators and Curves can all be assigned as Influence Objects to a smooth bound skin.

Select the Skin and then the Influence Object and join them through the Add Influence Tool.

 

Joints (Deformation Control in Rigid Binding)

Skin -> Edit Rigid Skin -> Create Flexor. An added bonus to Rigid Binding is the use of Flexors. Flexors un-kink geometry that becomes pinched or overly deformed as the shape’s underlying skeleton bends.

Flexors can be associated to both joints and bones.

 

Driven Animation

 

Driven Animation in Maya is powerful. Maya offers multiple options for driving the animation of an object without needing to set key-frames for each moment or change in path over time. Much animation can be relegated to a few attributes, including complex animations.

 

Expressions

Window -> Animation Editors -> Expression Editor. In this window, mathematical expressions can be created to control all keyable attributes. These expressions may, or may not, be based on the information from other attributes.

 

Set Driven Key

Animate -> Set Driven Key -> Key -> Options. As with Expressions, animating with Set Driven Key sets one attribute as the driver of one or more attributes. This animation is not based on time, but can be keyed.

NOTE:: You MUST set Driver attribute BEFORE setting the Driven attribute(s). Doing otherwise will reset the Driven attribute.

 

Constraints

[see ‘Constraints’ in Animation 1]

 

Blend Shapes

Though technically a deformation tool, the Influence attributes can be keyed and set. This tool is excellent for facial animations.

Deform -> Create Blend Shape. Select all objects of influence and select the object to deform last. Create the Blend Shape.

Any object in Maya with control points can be morphed inside of a Blend Shape. This includes geometry AND lattices. Therefore, while objects with disparate amounts of CVs can’t be directly linked in a Blend Shape, each shape can have a similar Lattice placed around the objects and thereby indirectly linking the objects with different component composition.

NOTE:: Objects with different component compositions CANNOT be directly linked in the Blend Shape Tool. If it is imperative that this happen, assign a similar lattice to each shape and connect the lattices in the Blend Shape.

 

IK Solvers

Inverse Kinematic Solvers are an Awesome way of controlling joint chains. With IK Handles (the controller handles for the inverse kinematic solver) at the end of the joint-chain – you have the ability to control the placement and bending of the chain quickly, and with ease.

 

RP vs. SC IK Solver

Each tool is used to determine the appropriate bending and curvature of many joints between two changing points. Their names are: Rotate Plane Solver and Single Chain Solver.

 

Skeleton -> IK Handle Tool -> Options -> [Choose ikRP Solver]. The RP Solver has robust functionality and therefore has more options to control. This solver calculates the rotations of the interior joints based on the orientation of the end effector to the goal. The RP Solver is not limited by the orientation of the IK Handle.

 

Skeleton -> IK Handle Tool -> Options -> [Choose ikSC Solver]. The SC Solver doesn’t have as many bells and whistles as the RP Solver. The SC Solver calculates the end effector’s movement based on the position AND orientation of the IK Handle. It is best to line up these joints so as to conform their curvature to a single plane. This aids in Not confusing the solver when calculating position AND orientation.

 

Differences between RP and SC:

1)    The RP requests ONLY the location information from the IK Handle when calculating solver movement – whereas the SC requests BOTH location AND orientation;

2)    2) the SC Solver can operate with other IK Handles running through its joints (though it is not recommended) – whereas the RP Solver cannot;

3)    3) The RP Solver gives control of the Pole Vector to the user – whereas the SC Solver has no user Pole Vector control.

 

Spline IK

Skeleton -> IK Spline Tool. Spline Solvers are ideal for character animation. Spline Solvers create, or require, a curve on which to map the position of the joints. From here, the Spline Solver can be rotated or moved. The CVs of the Spline Curve can be tweaked individually.

This is an excellent tool for animating a snake sliding along a path or for the back and forth motion of fish swimming.