Skinningskinning skin modifier:character rigging rig:skin modifier

Introduction to Character Rigging

Mirroring IK

 

Autodesk 3ds Max Tutorials > Character Animation Tutorials > Character Animation without Biped > Introduction to Character Rigging > 

Using Spline IK

Spline IK is a type of IK control that uses a spline to control a bone structure. You can change the object's shape by transforming the spline vertices. This is useful for animating such objects as a snake or a ponytail.

You can apply Spline IK when you create bones, or add it to the bone structure later on.

All the files necessary for this tutorial are provided on the program disc in the \tutorials\character_animation\intro_to_rigging directory. Before starting the tutorials, copy the \tutorials folder from the disc to your local program installation.

Create a simple spline IK structure:

1. Reset 3ds Max.
2. Choose Animation menu > Bone Tools.
3. On the Bone Tools floater, click Create Bones.

   The Create panel opens with the Systems category active, and the Bones button highlights.

4. On the IK Chain Assignment rollout of the Create panel, set IK Solver to SplineIKSolver and turn on Assign To Children.
5. In any viewport, create a series of at least six bones.

   When you right-click to end bone creation, the Spline IK Solver dialog opens.

   

6. Change Number Of Spline Knots to 4, and click OK.

   A spline is created in the shape of the bone structure. At each vertex on the spline is a box-shaped Point helper.

7. Right-click again in the viewport to exit bone-creation mode.
8. Select and move one of the helper objects.

   Moving a helper changes the shape of the spline, which in turn changes the shape of the bone structure.

   

9. Turn on Auto Key.
10. Go to frame 20 and move one of the box-shaped Point helpers.

    The bone structure animates according to the helper’s movement.

Apply IK after bone creation:

1. Load tut_splineik_start.max.

   

   This scene contains a snake mesh with a bone structure. The Skin modifier has already been applied to the mesh. The mesh is frozen so you can easily select the bones.

2. In the Top viewport, use Create panel > Shapes > Line to draw a curved line. Start the line near the bottom of the viewport, then draw upward.

   

   Drawing in this manner ensures the line’s first vertex will correspond to the head of the snake. The location of the first vertex sets the end at which the first bone in the IK chain will be placed. In this case, the first bone in the IK chain is at the snake’s head.

3. Select the snake’s head bone (Bone_Head).
4. Choose Animation menu > IK Solvers > SplineIK Solver.

   A rubber band line extends between the mouse cursor and the selected head bone.

5. Click the snake’s end bone, and then click the spline.

   The snake jumps to the spline and assumes its shape. Also, behind the scenes, the Spline IK Control modifier is applied to the spline, with box-shaped Point helper objects placed at the spline vertices.

   The helper objects might be a bit difficult to see at their default size in this particular context, so you can enlarge them in the Spline IK Control modifier.

   

6. Press H to open the Select Objects dialog, and then double-click the Line01 object name in the list to select the object and close the dialog.
7. Go to the Modify panel, where you'll see the Spline IK Control Parameters rollout. Near the bottom, change the Helper Display > Helper Size value to 40.0.

   The helpers are now bigger, and thus easier to see and manipulate.

   

   Now you can move and animate the helper objects to change the shape of the snake.

   

   TipIf the snake turns to lie on its side, select the Spline IK control (the cross hairs between the end bone and its parent). Go to the Motion panel, and on the IK Solver Properties rollout, change the Twist Start Angle to –90 or 90 .

Use Spline IK with a path constraint:

1. Load the file tut_splineikpath_start.max.

   

   This file contains the snake and a long, curvy spline. The Spline IK Control modifier has already been applied to the spline.

2. Select the snake’s head bone (Bone_Head).
3. Choose Animation menu > IK Solvers > SplineIK Solver.
4. Click the snake’s end bone, then right-click the viewport to end the process.

   A spline IK solver has been added to the bones, but is not associated with the spline.

5. Select the spline IK control by selecting the cross hairs between the end bone and its parent bone.

   

6. Go to the Motion panel. On the Spline IK Solver rollout, click the button under Pick Shape, and then click the spline.

   Now that the spline is associated with the spline IK solver, you have two choices for the remainder of the setup:

   • You can use a Position constraint to constrain the head bone to the first node (helper) on the spline. This is what happens automatically when you pick a spline while setting up the spline IK solver, as in the two previous procedures.
   • You can use a Path constraint to constrain the head bone to the spline, which will allow us to animate the snake along the spline.

   In this lesson you'll use the Path constraint.

7. Select the head bone.
8. Choose Animation menu > Constraints > Path Constraint, and click the spline.

   The snake jumps to the spline.

   The snake is automatically animated moving along the path, but it slithers backward.

   

   TipIf the snake turns to lie on its side, select the spline IK control and go to the Motion panel. In the IK Solver Properties rollout, change the Twist Start Angle to –90 or 90 .
9. Turn on Auto Key.
10. Select the head bone if necessary, and go to the Motion panel.
11. In the Path Parameters rollout, set % Along Path to 70.
12. Go to frame 100 and set % Along Path to 0.
13. Play the animation. The snake slithers along the path.

    

    You can also animate the box helpers on the spline to further control the animation.