Lesson 3: Setting up simple muscles

Open the scene for the lesson

1. Load the file you worked on in the previous lesson, or load the DragonLeg_Muscles_Start.mb file from the Lesson 3 folder.

   This file has the dragon leg with all the muscles and bones connected with default and basic Sticky weights applied to the capsules.

2. Do one of the following to change the skin mesh display so you can see the underlying rig:
   • In the Display Layer editor, turn off the lyrSkin layer to temporarily hide the skin as you work on the muscle.
   • From the panel menus, select Shading > XRay.

Create a simple muscle

While you can convert and rig any existing NURBS surface to be a muscle, Maya Muscle provides a tool to easily build and set up muscles interactively. In the next steps you use the Muscle Builder to create simple muscles.

1. From the main menu, select Muscle > Simple Muscles > Muscle Builder.

   The Muscle Builder window appears.

2. Using the Outliner window, do the following to load the muscle Attach Objects in the Muscle Builder:
   • Select the jntShoulder capsule and click for Attach Obj 1.
   • Select the jntLegLo capsule and click for Attach Obj 2.

     These buttons load the selected objects into the Attach Object fields for you.

3. Click Build/Update.

   A muscle shape is generated from the start Attach Object (Attach Obj 1) to the end Attach Object (Attach Obj 2). You may want to change your scene view to wireframe or X-ray mode while you work.

   Tip

   You can click the Attach Obj 1 or Attach Obj 2 buttons to directly select the attach locators and position them in the scene view.

   For this tutorial, you can leave the parameters in the Build tab at their default settings. If you want, you can adjust the simple muscle settings. See Build tab in the Maya Muscle guide to learn about the attributes available.

   Note

   If you scrub the timeline, the muscle stays attached but will not yet squash or stretch properly because you have not yet set up deformation.

   Once your muscle is generally placed and set, you can sculpt the muscle shape into something more specific.

Sculpt the simple muscle shape

1. In the Muscle Builder, switch to the Cross Section tab.

   This tab has three main sections. The list on the left shows you each cross section of your muscle. Typically the first and last cross sections are adjusted. There are two view panels showing you the view of all of your muscle cross sections down the length and from the side.

   
2. Select Curve 3 and Curve 5 from the Cross Section list. Note that you can move them on the X and Z-axis in the view panel.

   Selecting one or more items in the Cross Section curve list selects those curves. You can then move them in the view panels here, or in the scene view.

3. Click Edit Cross Section at the top of the tab.

   The cross sections are now active for editing and the view panels automatically switch to component mode so you can directly edit the points of the cross section curves.

4. Continue editing the cross sections until you are happy with the shape of the muscle.
   
   Tip

   You can pan in the view panels of the Muscle Builder. To easily re-center the view panels, click the Cross Section tab again.

5. When you are finished, click the EDITING label at the top of the tab to turn off the editing mode.

   You are now finished sculpting your muscle. In the next steps you finish the building process and rig the muscle to deform properly.

Finalize the simple muscle

1. In the Muscle Builder window, switch to the Finalize tab.

   This tab lets you choose how to deform and rig your muscle.

2. Ensure the Muscle Spline Deformer is selected, and Num Controls is set to 3.
   Note

   This gives you three movers: one at the start, one at the middle, and one at the end of the muscle.

3. Click Convert to Muscle.

   A warning dialog box appears to notify you that this operation will finalize the cross sections of this muscle. The dialog box also lets you select the base name of the muscle and controls.

   We recommend that you find a useful and readable naming scheme so that you can easily select and weight the muscles in the Muscle Paint window later. For example, if you create a muscle located near the upper leg, on the rear side in the center, you could name it "hamstringCenter".

4. Enter a name and click OK.

   The muscle is rigged and a cMuscleObject shape node is created. In wireframe mode, you can see three yellow box controls. These controls can be animated and have Jiggle settings on them that are created and constrained to the proper capsules.

   
5. Switch to the Muscle Parameters tab and scroll down.

   This section lets you customize the deformers on the selected muscles. You can also directly manipulate some of the controls in the Attribute Editor or Channel Box.

   To see the deformer attributes in the Channel Box, select the muscle surface.

6. Scrub the timeline frame by frame to see the muscle squash and stretch. After you have done this once, you can jump to any frame and adjust Muscle Parameters at any time and the playback is still correct.

Adjust the squash and stretch

Before you set the muscle squash and stretch, it's a good idea to set the minimum and maximum length of the muscle. By default, the muscle’s minimum squash is set to half its original length, and its maximum stretch is set to double its original length. When the muscle length changes to these settings, you get the maximum amount of volume change.

To adjust the squash and stretch length settings

1. Set the scene view shading to Smooth Shade All and turn off the lyrSkin layer in the Display Layer editor.
2. Leaving the Muscle Parameters tab of the Muscle Builder open, do the following to define the Squash pose:
   • Select the FootIKMover control and raise the leg to a squashed position.
   • Select the muscle surface.
   • In the Spline Length Settings section of the Muscle Parameters tab, click Set Current as Squash.
     

     This sets the muscle’s minimum squash value to the current length.

3. Do the following to define the Stretch pose:
   • Select the FootIKMover control and move it down so the leg is fully extended.
   • Select the muscle surface.
   • In the Spline Length Settings section, click Set Current as Stretch.
     

   Setting the minimum and maximum stretch length values cause the squash/stretch settings to more directly affect the visual output, since they are more closely related to the actual lengths the muscle is changing by. This can also help stop stretching from losing volume. In addition, this makes the Dampen On Squash and Dampen On Stretch values work properly.

4. Adjust the Stretch Volume Presets as required.

   Make sure you have the muscle surface selected so that changes you make in the Muscle Builder affect the muscle. The stretch settings let you set the basic X and Z-axis radial volume change for the start, middle and end of the muscle.

   If you are getting flipping when the muscle contracts, changing the Up-Axis can fix this. When the muscle is bent, the aim values set how the tips orient themselves.

   Tip

   You can play the animation and adjust the settings while the animation plays. Clicking a Stretch Volume preset automatically sets the values to one of several preset values.

View the Jiggle parameters

For Jiggle on simple muscles, you have overall control from the start to the middle to the end of the muscle. If you rig a muscle and create more than three movers, you can also directly set specific Jiggle values on the yellow movers. You can experiment to see the effect of the Jiggle Presets located on the Muscle Parameters tab of the Muscle Builder window.

To view the Jiggle parameters

1. Play the animation.
2. As the animation plays, click each of the Jiggle Presets buttons (Default, Light, Medium, Heavy, and OFF) to see the effect each preset has on the muscle.

Beyond the lesson

In this lesson you learned how to:

• Create a simple muscle using the Muscle Builder
• Sculpt and finalize a simple muscle
• Adjust muscle parameters

Because you rigged the simple muscle with the cMuscleSplineDeformer, you can also do custom muscle shaping to get exact control over how the muscle looks at various lengths. For further information see cMuscleSplineDeformer node and Set up a cMuscleSpline deformer in the Maya Muscle guide

As you build more simple muscles, note that in some cases, you may want muscles and bones to penetrate. For example when using Shrink Wrap, it's better to have a solid mass of muscles even if they penetrate than to have gaps or spaces between them.

You can now go back to the Build tab, select new settings, and continue building more muscles for your rig using the techniques you have learned. A completed muscle rig for this lesson called DragonLeg_Muscles_End.mb is located in the Lesson 3 folder.