Tendons Sub-Object

Select an object with the Physique modifier. > Modify panel > Sub-Object Tendon

After adjusting envelope parameters for good mesh deformation, use tendons to control the amount of skin stretching across multiple links. While envelopes provide smooth skin deformations, tendons provide additional stretching in much the same way that actual human tendons might create pulling in the wrist (several joints away) when the fingers are moved.

Workflow

To create a tendon from the spine to the upper arm, turn on Link sub-object and select a spine link. Click to turn on Insert and click the selected link to add tendon cross sections, then turn off Insert. Click Cross Section in the Selection Level area. Using the Rotate tool on the 3DS MAX toolbar, rotate a cross section so its control points are in useful locations. Use the Radius spinner in the Tendon Parameters area to scale the cross section radius so the control points fall close to the surface of the skin. Click Control Point, select a control point on the spine cross section, click Attach, and select the arm link. A tendon stretches from the spine to the arm. Finally, adjust Pull, Pinch, and Stretch to refine the movement of the skin.

Procedures

To create and attach a tendon

  1. Activate Tendons sub-object, and click Link in the Selection Level area.

  2. Select a link in the viewports.

  3. Click Insert.

  4. Position the cursor over the link in the viewports.

    The cursor changes to a small star.

  5. Click to create cross sections on the link.

    Right-click to deactivate Insert; the Insert button changes color from green to gray.

  6. Click Cross Section in the Selection Level area.

  7. Use the 3DS MAX Rotate tool to rotate the cross section so the control points are positioned in useful places.

  8. Use the Radius spinner to scale the cross section radially so the control points fall close to the surface of the skin.

  9. Click Control Point in the Selection Level area, then select one or more control point(s) on a cross section in the viewports.

  10. In the Edit Commands area, click Attach and select a link in the viewports.

    Tendons span the area between the links.

  11. Change the Pinch, Pull, and Stretch parameters as necessary to adjust skin behavior.

  12. Change Upper and Lower boundary parameters as necessary to control the extent of the effect on neighboring links.

To attach a tendon to another link

  1. Click Control Point to make it the active selection level.

  2. In a viewport, select one or more of the tendon's attach points.

    Click a point to select it; use CTRL+click to add points to the selection, or drag a rectangular region to select multiple points.

  3. Click to turn on Attach in the tendon Edit Controls area.

  4. In a viewport, click the link to which you want to attach the tendon.

    In the viewports, red lines appear showing the tendon's connection from its base to the other link. The Physique skin might also deform as a result of attaching the tendon.

    Tip: The tendon can have fixed attach points that are not connected to another link. These are useful for giving some rigidity to the skin, as when (in an actual body) a bone lies close to the skin's surface. For example, you might leave two fixed attach points on either side of a character's chest area, to simulate the effect of the sternum. When all tendons are attached to other links, the skin over the base link can have a "squishy" appearance when its animated. This is appropriate for some animated characters, but not for others.

    After you create a tendon and attach it, you can adjust it using the parameters in the Bulge Editor Tendon command panel and the boundary condition parameters in the Physique Tendons rollout.

To delete a tendon

  1. At the Link sub-object selection level, click the link that has the bad tendon.

  2. Click Delete in the Physique Tendons rollout.

    Tendons connecting upper chest to arms

Interface

Link: Click to select a link.

Cross Section: Click to edit cross sections.

Control Point: Click to edit control points on cross sections.

Previous/Next Link: Go to the previous or next link, cross section, or control point, depending on the selection level.

Sections: Set the number of base cross sections for the tendon.

Attach Points: Set the number of Attach Points around the tendon's base cross section.

Resolution: Sets the radial resolution around the base cross section. Attach points are constrained to one of the radial resolution lines.

Insert: Click to insert new cross sections on the selected link, or to insert a control point on a cross section. The action depends on the selection level: Link, Cross Section, or Control Point.

Delete: Click to delete cross sections or control points.

The action depends on he selection level: Link, Cross Section, or Control Point.

Radius: Scale Attach Points relative to the center of the cross section. Default=the average circumference of the skin where the tendon base is located.

Pull: Defines the strength of pull along the length of the link. Default=1.0.

Pinch: Defines the amount of pinch around the link circumference of the tendon base. Default=1.0.

Stretch: Defines the amount of stretch toward the attached link. Default=1.0.

The Pull, Pinch, and Stretch values work together to control, along a particular dimension, the strength of the one link (the attached link: call it link B) on vertices assigned to another link (the link where the tendon cross sections are inserted: call it link A). Vertices on link A behave as if they were under the influence of link B.

Pull

Defines the strength of pull along the length of the link. Default=1.0.

Pinch

Defines the amount of pinch around the link circumference of the tendon base. Default=1.0.

Stretch

Defines the amount of stretch toward the attached link. Default=1.0.

Pull, Pinch, and Stretch can all range from -2.0 to 2.0. At the default value of 1.0, the tendon's effect is full strength. Reducing the value of these parameters to a value between 0.0 and 1.0 reduces the strength of the tendon's effect. At values below 0.0, the tendon deforms the skin in the opposite direction. Pull, Pinch, and Stretch values between 1.0 and 2.0 cause an exaggerated effect, which is not usually needed for realistic effects.

Tip: Setting Stretch less than 0.0 can be useful in regions where movement typically pulls the skin inwards, as in the collarbone area or the buttocks.

Tip: As a general rule, leave the tendon values at 1.0 when the tendon is attached to a nearby link. For example, leave them at 1 between the upper spine (at the chest) and the arms. Reduce the Pull, Pinch, and Stretch values to reduce the tendon's effect when the tendon is attached to a more distant link. For example, reduce them between a lower part of the spine and the arms.

Attach: To attach a point, select the point, click Attach to turn it on, then select a different link in the viewports.

Detach: Detach a tendon on the selected control point at the Control Point selection level. At the Cross Section selection level, all attached tendons on the selected cross section are detached. At the Link selection level, all attached tendons are detached on all cross sections of the selected link.

Connect to Child Link: Allow tendons to affect the child link. This allows you to connect tendons across several links. Otherwise, there is a boundary between the links where no tendon effect occurs. Default=off.

Upper Bound: Set the upper boundary overlap. Upper Boundary values greater than 1.0 effect the child link.

Warning: Tendons that span several links can conflict with joint intersection parameters. In these cases, clear Active to turn off the joint intersection parameters for the joints that the tendon spans.

Pull Bias, Pinch Bias, Stretch Bias: Set Upper Boundary falloff effect. Values of 0.0 have no effect. Increasing the value shifts the Pull, Pinch, or Stretch effect toward the child. Default=0.5.

Connect to Parent Link: Allow tendons to affect the parent link. This allows you to connect tendons across several links. Otherwise, there is a boundary between the links where no tendon effect occurs. Default=off.

Lower Bound: Set the lower boundary overlap. Lower Boundary values less than 0.0 affect the parent link.

Warning: Tendons that span several links can conflict with joint intersection parameters. In these cases, clear Active to turn off the joint intersection parameters for the joints that the tendon spans.

Pull Bias, Pinch Bias, Stretch Bias: Set Lower Boundary fall off effect. Values of 0.0 have no effect. Increasing the value shifts the Pull, Pinch, or Stretch effect toward the parent. Default=0.5.

Interactive Redraw: Select to deform the mesh in real time, as cross sections and control points are edited 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 update.

Initial Skeletal Pose: Position the mesh to its pose when Physique was applied.

Display Options

Tendon Cross Sections: Toggle viewport display and change color for tendon cross sections.

Tendon Attach Points: Toggle viewport display and change colors for tendon attach points.

Tendon Attached Links: Toggle viewport display and change colors for tendon attached links.

Selected Tendon Elements area

Cross Sections: Change viewport color of selected cross section.

Attach Points: Change viewport color of selected control point.

Attached Links: Change viewport color of selected link.

 

 

 


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