Set up a Muscle Spline deformer
 
 
 

The Muscle Spline deformer is a deformer node that lets you deform any object based on a Muscle Spline. Since the deformation is based on the spline information, much of the previous section is related. The deformer itself takes connections/inputs from a Muscle Spline object as discussed earlier, and all of the Jiggle is based on the spline jiggling. Since the object is deformed from the spline curve, the geometry changes as the spline curve moves or changes.

The Muscle Spline deformer is the typical deformer used to get muscle control. It has several main options including basic Squash and Stretch, and custom muscle/geometry shaping based on spline length.

To apply a Muscle Spline deformer on any object

  1. Select the object you want to apply the deformer to.

    Typically, this is a NURBS surface so that the object can act as a muscle, but it does not have to be. A basic NURBS object is used in the following example.

  2. Select Muscle > Simple Muscles > Apply Muscle Spline Deformer from the main menu bar.

    The Muscle Spline Deformer window appears with options for creating the Muscle Spline deformer node. See Muscle Spline Deformer window.

  3. In the Muscle Spline Deformer window, do the following:
    • Enter a unique Name for the deformer and related items.
    • Enter the number of control points you want the spline to have.
    • Select the shape you want for the control points from the Type drop-down menu.
    • Click Setup Muscle Spline Deformer.
  4. When finished, you can close the Muscle Spline Deformer window.

    The geometry is rigged. A Muscle Spline node is created, a Muscle Spline deformer is applied to the surface, and all of the needed spline information is connected into the deformer.

  5. Move or animate the spline controls to deform the object based on the spline curve.

Related topics

Reset Base Pose for Muscle Spline deformer

Once a Muscle Spline deformer is created, the control curve and controls are automatically placed inside the surface. In some cases, you may want to adjust the default location of the controls without affecting the surface. This lets you set up exactly where and how the curve is shaped before deformation is applied.

To do this, you adjust the controls, then reset the base pose for the deformer. This makes the current shape of the curve the default.

To reset the Base Pose for a Muscle Spline deformer

  1. Select an object that has a Muscle Spline deformer on it.

  2. Find the envelope attribute under the main shape in the Maya Channel Box or Attribute Editor, and set the envelope attribute to 0 to disable it. (This step is optional, but you usually want to do this.)

  3. Move or adjust the controls to create a new default state of the spline.

  4. Re-select the object being deformed by the Muscle Spline deformer.

  5. Adjust the envelope back to 1.0 to see how the muscle looks with the curve in this state if it deforms. (You can also do this step at the end if you prefer.)

  6. Select Muscle > Simple Muscles > Reset Base Pose for Muscle Spline Deformer.

    After a moment the object is reset as if it was not deformed. The current state of the spline is now used as the default state for the deformation.

  7. Move the controls to see how the object deforms differently with the new default spline state.

Set up custom muscle shapes with the Muscle Spline deformer

If you use the Muscle Spline deformer, you can also use Custom Muscle Shaping. This tool lets you directly modify and sculpt the exact muscle deformation and shape you want for any length that the muscle is at. As the muscle length changes, each custom shape you make is triggered.

This is similar to creating a blendshape for the muscle driven by the muscle length, except that the deformation is tied directly into the Muscle Spline deformer, and you can directly modify the shape of the muscle in the current pose instead of having to sculpt in the original reset pose.

To set up custom muscle shapes

  1. Select an object that is rigged with a Muscle Spline deformer for its deformation.

  2. If you want to scrub to different frames, disable any Jiggle on the deformer controls.

    If Jiggle is on, the shaping you see is not accurate because the muscle shape includes the Jiggle effect. You can disable Jiggle by selecting each muscle control and setting the Jiggle amount for each to 0, or using the Muscle Parameters tab.

  3. With the muscle selected, select Muscle > Simple Muscles > Custom Muscle Shapes from the main menu bar.
  4. The Muscle Spline Deformer Shape window appears, with the name of the object and deformer at the top. If you have not already selected a muscle, you can press the button to load the selected geometry.

  5. Pose the muscle into the problem pose where the length causes it to deform into an undesirable shape. Notice how the Current State slider at the bottom of the window changes as the length of the muscle changes. A value of -1 means the muscle is totally squashed, +1 means totally stretched, and 0 means it is at the default length.

  6. Click Prep for Sculpt. The temporary piece of sculpting geometry appears with the points ready for editing. The color changes to reflect that you are in Sculpting mode. You can adjust the temporary color using the color swatch next to the Prep for Sculpt button.

  7. Sculpt any changes on this temporary sculpt object to make the muscle look how you want it at this length. \

  8. If you are creating a new shape for this length, click Create New. If you are fixing an existing shape, select the shape from the list on the right and click Edit.
  9. If you click Create New, a window appears asking for the name of the new target shape pose. Enter a unique name and click OK.

    After a moment, the original object appears with the correction applied to it. The new or edited pose appears in the list on the right side of the window with the Current State value the shape was made at next to the name.

  10. Adjust the muscle length interactively or play your animation.

    The muscle goes into the sculpted pose whenever it reaches the specified length. You can adjust the Blend value to control how the fading on and off for the shape occurs. Lower values make the shape appear only when the length is close to the length where the sculpt was done, larger values blend on even if the length is farther away. You can also edit the existing pose, or create more poses for other lengths.