Select an object with the Physique modifier. > Modify panel > Sub-Object Bulge
After you edit envelope parameters for good overall mesh deformation, create bulge angles to simulate muscle contraction and expansion when a character's limb rotates.
A bulge angle requires two links, the selected link and the child link of that selection (upper arm and forearm, for example). The joint that separates the two is referred to as the bulge joint. Any rotation applied to this joint becomes the angle used to center the effect of a bulge angle.
Physique creates a single default bulge angle for each bulge joint in the attached skeleton. The angle of this joint is that of the initial skeleton pose, created when the Physique modifier was applied to the skeleton, or when the Reinitialize command is used with Initial Skeleton Pose selected.
To create a biceps bulge angle, activate Bulge sub-object and click Link. Select the upper arm link, then click Insert Bulge Angle; the bulge angle name increments from 0 to 1 in the Current Bulge Angle field, indicating a new bulge angle has been created. Type a descriptive name for the new bulge angle in the Current Bulge Angle field, like Arm at 90, for example.
Click Bulge Angle Color and select a color for the newly created bulge angle. When Select Nearest Bulge Angle is active, the bulge angle color changes as the joint bends; this is a good visual indicator of which angle has the most influence at any given frame.
Scrub the time slider to a frame where the arm is bent to 90 degrees, then click Set Bulge Angle (you can also rotate the joint). Click Cross Section and Insert, then position the cursor over the upper arm link in the viewports to place a cross section for the biceps.
Click Control Points and move the cross section control points in the viewports to edit the cross section and bulge the biceps. Click Play, the biceps continues to grow as the angle of the character's arm approaches 90 degrees. If Select Nearest Bulge Angle is active, the bulge angle gizmos change colors, depending on which angle has the greatest influence.
Note: The Set Bulge Angle command only records the angle between the biceps and forearm, not the frame number where that angle occurs. Click Link and use Copy, Paste, and Mirror to create an identical bulge angle for the opposite arm.
Tip: Load a .bip file that will rotate the character's limbs. Turn on In Place mode before you scrub the time slider to locate appropriate limb angles. This keeps the character (biped) in the viewports.
After creating a new bulge angle with the Insert Bulge Angle command, scrubbing to frame 3 of this running motion puts the character's arm at a 90-degree angle, perfect for using the Set Bulge Angle command. Refer to the images above. The three cross sections that control the biceps "bulge" are created by clicking Cross Section and Insert, then clicking the upper arm link in the viewports. Click Control Point and drag the cross section control points to "bulge" the mesh or use the Cross Section view in the Bulge Editor to drag control points to "bulge" the mesh. Give each newly created bulge angle a name and color to make identification simpler.
The Bulge Editor duplicates many of the controls in Bulge sub-object. The benefit of using the Bulge Editor is that bulge angle data is represented graphically and provides an alternative way of creating, selecting, and editing cross sections. Rather than editing cross section control points in the viewports to "bulge" the mesh, you may prefer to open the Bulge Editor and move control points in the Bulge Editor's Cross Section view.
To create a new bulge angle on a selected link
With Bulge sub-object active, click Link in the Selection Level area.
Select a link in the viewports.
Click Insert Bulge Angle.
This creates a new bulge angle. The name in the Current Bulge Angle field increments. Give the new bulge angle a descriptive name.
In the Current Bulge Angle field, type a name, such as "Arm at 90".
Click the Bulge Angle Color swatch and choose a color in the color dialog.
This makes identification much simpler. Now a joint angle must be set for the newly created bulge angle.
Exit Bulge sub-object level.
Select and rotate the bone at the joint where you want the bulge. Select the mesh again and return to Bulge sub-object level.
Click Set Bulge Angle. The actual joint angle between the link and its child is recorded (for example, the angle created by the biceps and forearm is the actual joint angle, if the biped upper arm link is selected).
Click Cross Section and use Insert to create and position a cross section, if one does not exist where the mesh should bulge.
Scale a cross section or move control points on a cross section to create the bulge: click Cross Section or Control Point in the Selection Level area, depending on how you want to deform the mesh.
Enter 80 in the Influence field.
If the bulge angle is for a biceps bulge when the forearm and upper arm create a 90-degree angle, the bulge begins to appear at 10 degrees.
Note: By default one bulge angle is created by Physique in the initial skeletal pose; the arm is usually straight in this pose.
To copy all Bulge angles for one link to it's opposite
Turn on Bulge sub-object.
Select a Link to copy in the viewports.
Choose Entire Link in the Current Bulge Angle dropdown.
Select the opposite link in the viewports.
Click Paste, and then click Mirror.
All the bulge angles from the first link are pasted to the opposite link.
To choose a specific bulge angle for editing
Click the arrow by the Bulge Angle dropdown.
The full list of bulge angle names appears for the current link.
Click the name of the bulge angle you want to edit.
The viewports update to show the cross sections associated with the newly selected bulge angle.
To change a bulge angle value
In the Bulge rollout, make sure the bulge angle's name is displayed in the Current Bulge Angle dropdown.
In a viewport, scrub to another frame displaying the angle you want to record, or use the 3DS MAX transforms to change the angle between the active link and its child link.
In the Bulge rollout, click Set Bulge Angle.
To delete a bulge angle
Click the downward pointing arrow of the Bulge Angle dropdown.
The full list of bulge angle names is displayed.
Click the name of the bulge angle you want to delete.
Click Delete Bulge Angle.
You can't delete the default bulge angle—a link must always have at least one bulge angle defined.
To use Select Nearest Bulge Angle
The Select Nearest Bulge Angle button can be useful to help you identify the bulge angle that has the greatest effect at the current pose.
Click Select Nearest Bulge Angle.
Scrub the time slider or rotate the joint.
The bulge angle named in the dropdown list changes to the most influential bulge.
Selection Level group
The Insert, Delete, Copy, Paste, and Mirror commands work according to what is turned on in the Selection Level area.
Link: Click to select links in the viewports. The Copy, Paste, and Mirror commands are enabled for links.
Cross Section: Edit cross sections to "bulge" the mesh. Click to select cross sections in the selected link in the viewports. The Insert, Delete, Copy, Paste, and Mirror commands are enabled for cross sections.
Control Point: Click to edit cross section control points on the selected link.
Next/Previous Link: Selects the next or previous link, cross section, or control point depending on the selection level.
Bulge Editor: Create and edit bulge angles using the Cross Section and Profile views in the Bulge Editor. Displays the Bulge Editor.
Select Nearest Bulge Angle: Turn on to select the bulge angle nearest to the current joint angle. If a joint bends over time, you can use the time slider to select a bulge angle. If you click Play, you can see the Current Bulge Angle field change to reflect the nearest bulge angle to the current angle of the selected link and its child (if two or more bulge angles for the limb exist).
Current Bulge Angle (field): Displays the current Bulge Angle. Type a descriptive name for a newly created bulge angle. When you click Insert Bulge Angle, this field displays the new bulge angle name. Use the dropdown to select other bulge angles.
Entire Link: in the Current Bulge Angle dropdown selects all cross sections for all bulge angles in the selected link. Use this to change cross section parameters globally for a link. This also affects the Copy and Paste commands. While Entire Link is selected, Copy Cross Section copies all cross sections for all bulges, and Paste Cross Section pastes all cross sections for all bulges. Entire Link is useful for copying all the bulges from one arm or leg to another.
Bulge Angle Color: Changes the current bulge angle color. Giving each bulge angle a different color is a good way to distinguish between them.
Set Bulge Angle: Changes the angle value to the skeleton's current joint angle on the current bulge angle (visible in the Current Bulge Angle field). First use Move or Rotate in a viewport to change the angle between the selected link and its child, then click Set Bulge Angle.
Insert Bulge Angle: Adds a new bulge angle for the selected link. The Current Bulge Angle field displays a bulge angle name with the number incremented. Type a descriptive name for any new bulge angle, such as "Arm at 90".
By default, one Bulge Angle is created in the Figure mode pose when Physique creates links. Only one additional bulge angle will allow you to bulge the mesh. You can create more bulge angles for further control, if you want.
Delete Bulge Angle: Removes the current bulge angle at the selected link.
Influence: The range of angles through which the bulge influences the skin. Range =0 to 180; Default=90 degrees.
For example, if you've set a bulge angle for the joint at 90 degrees, an Influence value of 40 means that the bulge effect begins to appear when the rotating joint reaches 50 degrees (90-40) or 130 degrees (90+40).
Power: Controls how smoothly or abruptly the bulge takes effect. At 0, the bulge takes effect immediately, without interpolated easing. As values increase, the bulge eases in gradually. A value of 10 will bulge the mesh abruptly when the set angle is reached. Range=0 to 10; Default=2.5.
Weight: Increases the effect of the current bulge angle relative to the effect of any other bulges. Range=0 to 100; Default=1.0.
Sections: Sets the number of cross sections for the selected link.
Divisions: Sets the number of control points evenly distributed around the cross section.
Resolution: Sets the number of radial divisions around the cross section. Control points snap to the nearest resolution line.
Insert: Creates a new cross section or control point; depends on what is on in the Selection Level area.
Delete: Deletes a cross section or control point.
Copy: Copies bulge angels and cross sections, depending on which is active in the Selection Level area.
Paste: Pastes links and cross sections, depending on which is active in the Selection Level area. To copy and paste all the bulge angles from one link, select Entire Link in the Current Bulge Angle field, and then click Copy. Select the opposite link and click Paste. Click Mirror to mirror the pasted link parameters.
Mirror: Mirrors bulge angles and cross sections on bulge angles. Use Select and Rotate, then click and drag over a link or cross section to orient bulge angles and cross sections, if necessary.
Interactive Redraw: Select to deform the mesh in real time as you edit cross sections and control points in the viewports. Clear to update the mesh on mouse-up. Clear Interactive Redraw on slow systems or with dense meshes that take too long to compute in real time.
Initial Skeletal Pose: Put the mesh into its original pose when Physique was first applied.
Display Options: Sets viewport display options.
Sides: Specifies the number of sides the bulge angle envelope displays in the viewports.
Scale: Specifies the scale of envelope display in the viewports.
Default Color: Changes envelope color in the viewport display.
Active Viewport Display
Selected Cross Sections: Changes the color of selected cross sections in the viewports.
Selected Control Points: Changes the color of selected Control Points in the viewports.
Orientation Bar: Changes the color of the Orientation Bar in the viewports.
The Orientation Bar displays in the viewports when the Bulge Editor is open.
Profile: Changes the color of the bulge profile.
The bulge profile displays in the viewports when the Bulge Editor is open.