Manipulating Points by Volume
Volume deformations are a modeling tool consisting of a spherical control object that you can use to move an object’s points. Only points within the control object are affected, with a proportional falloff from the center.
Scaling a volume deformer applied to a cluster.
About Volume Deformations
Volume deformations have two parts:
• A volume-deform object, or volume deformer, is a control object you can use to deform geometric objects. It is represented by a spherical icon with little “clamps” in the 3D views. Points that lie inside the sphere’s volume are affected by the deformation.
• A Proportional Volume operator is applied to a geometric object when you attach and transform a volume deformer.
There are two ways to use volume deformations:
• As a modeling tool, you attach the volume deformer, transform it, then detach it, re-attach it elsewhere, transform it again, and repeat. This adds a series of separate Proportional Volume operators to the construction history.
• As an animation tool, you attach the volume deformer once and then animate its transformations.
Volume deformers are spherical shapes that define the points that are affected on the deformed object.
To get a volume deformer
1. If desired, first select some objects, clusters, or points to deform. The control object will be automatically attached to the selected elements.
2. Choose Get > Primitive > Control Object > Volume Deform from any toolbar. A volume deformer is added to the scene.
- If any geometric elements were selected, the volume deformer is attached to them. A Proportional Volume operator is automatically applied and its property editor opens.
- If no geometric elements were selected, the volume deformer is initially attached to nothing and its property editor opens instead.
To set volume deformer properties
Open the volume deformer’s property editor. A quick way to do this is to select the volume deformer and press Enter.
• Radius controls the untransformed size of the volume deformer.
• Remember Attached Objects controls what happens when you attach the volume deformer.
- If it is on, the deformation is applied to the same elements (objects or clusters) as before.
- If it is off, the deformation is applied to all visible geometric objects that are wholly or partially within the control object’s volume.
You can exclude geometric objects by hiding them before you attach the control object. Alternatively, you can attach elements manually as described in.
Applying Volume Deformations
To deform by volume, you first use the volume deformer to define the volume of influence and then you apply the volume deformation operator.
If you want to animate the volume deformer’s transformation to change the shape of the geometry, leave the volume deformer attached. Otherwise, you can use the volume deformer as a modeling tool by detaching it, defining a new volume of influence, applying another volume deformation operator, and repeating.
To attach or detach a volume deformer
• Select the volume deformer and do one of the following:
- Press Shift+V.
- Choose Modify > Component > Attach/Detach Volume Deform from the Model toolbar.
The volume deformer’s icon changes to show whether it is attached or detached. When you attach it, the geometries that are affected depend on the deformer’s Remember Attached Objects parameter — see.
To apply a volume deformation
1. Make sure that the volume deformer is not attached.
2. Define the points to affect by adjusting the size, shape, and position of the volume-deform object.
For example, you can scale, rotate, and translate the object, as well as adjust its radius. Once the deformer is attached, it will affect only those points within its volume.
To apply a volume deformation
1. Attach the volume-deform object.
2. Scale, rotate, and translate the volume-deform control object. Points within the volume on the attached elements are deformed accordingly.
As you continue to transform the control object, no new Proportional Volume operator is applied; instead, the current operator is updated. You can adjust its falloff and other properties as described in.
3. When you are satisfied, you can detach the volume-deform control object, and then repeat the entire procedure to continue sculpting your objects.
Attaching Geometry Manually
You can attach geometric elements to volume-deform objects manually. This is useful, for example, if you want to restrict a deformation to a particular cluster.
To manually attach geometric elements to volume-deform objects
1. Select one or more objects, clusters, or points.
2. Choose Modify > Deform > by Volume from the Model toolbar. This command is also available on the Animate and Simulate toolbars.
3. Pick a volume-deform control object.
- If the control object was not attached to anything, it becomes attached to the selected elements.
- If the control object was already attached, the selected elements are added to the list of attached geometries.
Setting Volume Deform Operator Options
The Proportional Volume operator controls parameters like the strength and falloff of the deformation. You can modify the current operator or set the defaults for future operators in your scene. Of course, you can always use an explorer to open the property editor of any previously applied operator as well.
To modify the current (last) operator
• With the volume deformer selected, choose Modify > Component > Inspect Volume Deform from the Model toolbar.
To modify settings for future operators
• Choose Modify > Component > Volume Deform Setup from the Model toolbar.
Power controls how closely the deformed points follow the center of the volume deformer as it is transformed.
• When Power is 100, the points follow exactly.
• When Power is 50, the points follow halfway.
• When Power is greater than 100, the points overshoot.
• When Power is negative, the points move in the opposite direction.
Power = 100
Power < 100
Power > 100
Start Damping defines a radius within which the deformation has full power and after which it falls off. Values are a percentage of the volume deformer’s radius.
• At 0, the Power falls off from the center.
• At 100, all points within the volume are deformed with full Power.
• Between these values, an inner sphere shows the radius at which the falloff begins.
Start Damping = 0
Start Damping > 0
When Envelope Mode is on, the deformation is relative to the volume deformer’s parent. This option is useful if you are using volume deformers parented to envelope deformers to create bulging muscles. The volume deformer will not affect the envelope as it moves with its parent, but only when it transforms relative to its parent.
Interpolation controls how the deformation is calculated.
• Linear is faster to calculate.
• Transform may give better results, particularly when the volume deformer is rotated.
Falloff Profile controls how the Power falls off from the Start Damping radius to the end of the volume deformer’s radius. You can edit the profile curve using the mouse and the same keyboard commands as the animation editor or right-click to display a menu.
Animating Volume Deformations
If you wish to animate an object’s deformation by animating the transformations of a volume deformer, then you must leave the volume deformer attached.
Note that you can also animate the Proportional Volume operator’s properties, such as Power and Damping.
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