8
684 Chapter 8: Modifiers
• On a NURBS surface, the Flex modifier
influences control vertices (CVs) or points.
• On a Spline (shape), the Flex modifier
influences both control points and tangent
handles.
• On an FFD Space Warp, the Flex modifier
influences control points.
Effects
You can apply space warps to the Flex modifier.
For example, you can add Wind to animate plants
and trees, or a waving flag. In such cases, you don’t
need to create key frames to see the effects; the
space warp alone can animate the surface.
Character Animation
Use Flex above the
Skin modifier (page 1–781)
to
add secondar y motion to a character animated
w ith Bones. If you are using the 3ds Max product,
useFlexabovethePhysiquemodifiertoadd
secondary motion to a character.
Pr ocedur es
Example: To paint on weights:
1.
CreateasphereontheleftsideoftheTop
viewport.
2. Turn on the Auto Key button and
movethetimeslidertoframe50.
3. In the Top viewport, move the sphere to the
right side of the v iewpor t.
4. Tur n off Auto Key.
5. On the Modify panel, click Modifier
List, and then choose Flex.
The Flex modifier is applied to the sphere.
6. Click Play.
The sphere flexes around the Transform gizmo
evenly.
7. Open the Flex modifier hierarchy in the stack
display, and click Weights & Springs.
This enables modification of the Weights &
Springs sub-object settings.
8. InthePaintWeightsgroup,turnonPaint.
9. IntheLeftviewport,paintonthelowerpart
of the sphere.
Thevertexcolorchangesasthevertexweight
changes. Yellow vert ices are more r igid, blue
ver tices are less r i g id.
Note: You can change Flex vertex colors
through Customize menu > Customize User
Interface > Colors > Geometry > Subselection
Hard/Medium/Soft.
10. Click Play.
Thespherewobblesononesidemorethanthe
other.
If the Strength setting in the Paint Vertex group
is a positive value, you paint rigidity. If the
values are negative, you paint flexibility.
Paint with negative numbers for Strength to
reverse the effect.
Ex ample: To use wi nd as a for ce:
1.
In the Top viewport, create a sphere.
2. On the Create panel, click Space
Warps, and then, if necessary, choose Forces
from the drop-dow n list.
3. Click Wind, and then click and drag in the
Front viewport to create a wind gizmo.
4. On the Wind Parameters rollout, set Strength
and Turbulence to 4.
5. Select the Sphere.
6. Apply the Flex modifier.
7. On the Modify panel > Parameters rollout, set
Samples to 1.