Open the scene for the lesson

1. Load the tut_dragonLeg_basic_START.ma file.

   This scene contains a basic polygon mesh of a leg, some joints with a simple IK chain rig with animation on it, and some background lights. You can use the Display Layer Editor to show and hide various parts of this rig.

2. In the Display Layer Editor, turn off the "lyrSkin" and “lyrLIGHTS” layers to hide the skin and view the underlying rig.
3. Scrub the timeline to view the animation.

   You can see the basic IK rig setup as the leg moves back and forth over time. In addition to the basic Maya joints, there are two polygon bone objects for the hip blade and kneecap.

Set up muscles

Currently, there is no stable root joint for this rig. Rather than creating a Maya joint as the root, and since you will be using the Muscle deformer for skinning, you can create a capsule object to use as the root.

Capsules are like joints, except that they have a true size and thickness and can be used by the Muscle skin deformer as both joints for Sticky weighting and actual sliding effects. They effectively work as bones, and are faster than polygon mesh bones.

To create and set up a capsule object

1. Select Muscle > Muscles/Bones > Make Capsule to create a capsule object.

   A capsule object appears at the origin. A group called “grpMUSCLES” that holds all created capsules and muscles is also created to aid in keeping your rig hierarchy clean.

   NoteSince capsules are locators, you must have Show Locators turned on the scene view’s Show menu in order to see them.
2. Select Muscle > Simple Muscles > Set Muscle Parameters to open the Muscle Builder window.

   The top of the Muscle Parameters tab allows you to edit basic attributes for capsules, bones and muscles.

   NoteYou can also use the Attribute Editor or Channel Box to control Muscle deformers and settings for any capsule, bone, or muscle.
3. In the Muscle Object Settings, adjust the capsule’s Length to a value of 4. If you wish, you can adjust the other muscle object settings.
4. Close the Muscle Builder window when you are finished editing the parameters.
5. Move and rotate the capsule to a position beside the boneBlade shape as shown in the following image. This is a good location for your root object.

   Since only objects that have a cMuscleObject shape node can be connected to the Muscle skin deformer for skinning, you need to convert all of the joints and polygon bones.

Convert the joints to bones

Rather than manually creating a capsule by hand for each joint, Maya Muscle provides an automatic way to convert joints to capsules so that they can be directly connected. Converted joints function as both a regular Maya joint and a Muscle capsule object.

1. Select all of the joints in the dragon leg rig.

   

2. Select Muscle > Muscles/Bones > Convert Surface to Muscle/Bone.

   Since you are converting joints and not a surface, a Joint to Capsule Conversion window appears. You need to know which axis is running down the length of the joints in your rig. The default for Maya is X. However, on this rig a custom Joint Orient tool was used to get a cleaner joint rotation axis. It is highly recommended you use this sort of tool to set up your Orient a joint’s local axes manually before rigging.

3. Click Y-Axis , since the y-axis runs down the length of the joints in this scene.

   Each joint is also converted to also be a capsule object. Using the tools learned so far, you can adjust the colors and lengths of the capsules.

   

   Since you did not originally select the polygon bone objects when you converted, you must also convert these mesh objects so that they also can be connected into the Muscle deformer for skinning.

4. Select the kneecap and blade bone objects, then select Muscle > Muscles/Bones > Convert Surface to Muscle/Bone.

   The polygon mesh objects are properly converted and connected to a new cMuscleObject shape node.

   

   While there is no visible change, this shape now exists and can be seen in the Channel Box. You can also use the Muscle Builder dialog box to turn on display of the shape and adjust colors or other features as well. Make sure you leave the Strength setting at 1.0.

Now that you have a series of joints and polygon mesh objects that have been converted to work with the Muscle skin deformer, you can apply the skin deformer and connect the muscle objects.

Apply the Muscle skin deformer

For the Muscle skin deformer, only select the mesh you are applying the skin to. You connect the bones and muscles afterwards.

To apply the Muscle skin deformer

1. Turn on the “lyrSkin” layer in the Display Layer Editor and select the dragon leg skin mesh.
2. Select Muscle > Skin Setup > Apply Muscle System Skin Deformer.

   As the deformer is applied, a dialog box appears to pre-calculate required information for the Relax deformer in case you use it later.

   When the process is complete, the dragon leg mesh looks the same, but it now has the Muscle skin deformer applied. You can view the cMuscleSystem1 node in the Channel Box.

   At this point, animating the mesh will have no deformation effect, because you have not yet connected or weighted any bones or muscles to the skin mesh. In the next steps, you will connect all the capsules and bones.

Connect the muscle objects

1. Go to frame 0 in the Time Slider to make sure the bones/capsules are in their default base pose.
2. Select the following in the Outliner:
   • All of the capsule objects created in the previous lesson, including the root capsule object and all the joints that you converted to capsules.
   • The two polygon bone objects (boneKneeCapRt and boneBlade).
   • The skin mesh (pSkinMesh).

     

3. Select Muscle > Muscle Objects > Connect selected Muscle Objects.

   After a moment, all the bones are connected into the Muscle deformer. At this point, scrubbing the timeline still does not produce any motion on the skin mesh because you have not yet applied the default skin weights.

Apply default weights

Applying default weights to bones and polygon mesh objects is similar to weighting with the Maya skinCluster. The points on the skin will move when the capsule/bone moves.

To apply default weights

1. Select the skin mesh (pSkinMesh).
   TipIf the Muscle Paint tool is open, you can see the weights when the operation is complete.
2. Select Muscle > Weighting > Apply Default Weights.

   The Default Weights tool appears. There are several options available, depending on the selected Weight type. See Default Weights tool for a detailed description.

   

3. Select Sticky from the Weight drop-down menu.
4. Set the Smooth value to 3. The Smooth value sets how many iterations the smooth operation applies.
5. Click Apply Default Weights.

   Now that you have applied default Sticky weights, scrubbing the timeline shows the effect. The skin mesh moves when the bone capsules move.

This concludes the first lesson of the Simple Muscles tutorial. A completed file for this lesson, tut_dragonLeg_basic_END.ma, can be found in the sample files directory.

Beyond the Lesson

In this lesson you learned how to:

• Create a capsule object
• Convert joints to bone capsules
• Apply the Muscle deformer to a skin mesh
• Connect bone and capsule objects to a skin mesh
• Apply default weights to a rig

Now you are ready to refine the default weighting on your dragon leg mesh by painting weights with the Muscle Paint tool.