3ds Max 2012 Bible - Kelly L. Murdock [432]
After the vertex weights are set, you can click the Bake Selected Vertices to lock down the weight values. Changes to envelopes do not affect baked vertices.
Painting weights
Using the Paint Weights button, you can paint with a brush over the surface of the skin object. The Paint Strength value sets the value of each brush stroke. This value can be positive (up to 1.0) for vertices that will move with the bone or negative (to –1.0) for vertices that will not move with the bone.
To the right of the Paint Weights button is the Painter Options button (it has three dots on it), which opens the Painter Options dialog box.
Cross-Reference
The Painter Options dialog box also is used by the Vertex Paint modifier and the Paint Deformation tool. It is described in detail in Chapter 13, “Modeling with Polygons.” •
Tutorial: Applying skin weights
In this example, you change the skin weights of the future man character in an attempt to fix the problem you saw with his boots.
To apply the skin weights to a character, follow these steps:
1. Open the Future man with skin final.max file from the Chap 40 directory on the CD.
2. With the mesh skin selected, open the Modify panel and choose the Bip01 L Foot bone in the bone list. Then click the Edit Envelopes button at the top of the Parameters rollout. This displays the envelopes around the foot object. Zoom in on the foot object, and change the display option to Realistic or press the F3 key, so you can see the weight shading.
3. Make sure the Cross Sections option in the Select section of the Parameters rollout is selected. Then select the cross-section handles on the outer envelope and pull them in toward the foot. Rotate the side to make sure that the toe and heel of the boot are still covered.
4. Click the Vertices option in the Parameters rollout, and disable the Backface Cull Vertices option. Drag over all the vertices that are contained in the lower part of the boot, and enable the Rigid option. Then select the vertices above the boot in the shin. You can use the Loop button to select all vertices about the upper part of the boot and press and hold the Alt key to remove any vertices that are part of the lower boot.
5. In the Weight Properties section of the Parameters rollout, click the Weight Tool button. In the Weight Tool dialog box, click the .25 button. This changes the weight of the selected vertices. Then click the Blend button to smooth the transition areas.
6. Click the Edit Envelopes button to exit Edit Envelopes mode. Then select and rotate the upper leg to see whether the problem has been fixed. As I rotated my model, I noticed that some vertices on the back of the boot were left behind, which means that they aren't being influenced by the foot bone.
Caution
Be sure to undo the upper leg rotation before making changes to the envelopes, or the envelopes will move along with the rotation. •
7. Enter Edit Envelopes mode again, and click the Paint Weights button. The cursor changes to a round brush. Click the Brush Options button (which is next to the Paint Weights button with three dots). This opens the Brush Options dialog box. Set the Max Strength value to 1.0, and close the dialog box. Then paint in the viewport over the vertices on the back of the boot heel, including those areas that aren't shaded red. Figure 40.7 shows the correct boot with its envelopes.
8. Exit Edit Envelopes mode again, and check the changes by rotating the upper leg bone.
FIGURE 40.7
Vertices' weights can be fixed with the Weight Tool and by Painting Weights.
Mirror settings
Most characters have a natural symmetry, and you can use this symmetry to mirror envelopes and vertex weights between different sides of a model. You can use this feature by clicking the Mirror Mode button