Waves

 
 
 

Waves are animated deformations that travel in both time and space. You can create shock waves, water waves, and other types of natural disturbances with wave deformations.

Waves are animated deformations whose amplitude changes over time. You can:

Wave Control Objects and Wave Operators

There are two basic parts of a wave deformation: the wave control object and the wave operator.

Wave Control Objects

The wave control object controls the basic parameters that are intrinsic to the wave itself, such as its speed and shape. Each wave control object can be used to deform any number of objects in a scene.

The wave control object is represented by a wireframe icon in the geometry views; there are different icons for the different types of wave. The position of the wave control object also defines the "epicenter" of the wave and its orientation defines the direction of the waves.

Wave Operators

The wave operator deforms an object or cluster by "attaching" a wave control object. The wave operator is a node in the object's operator stack. It controls the parameters that are specific to how the wave affects a particular object, such as the spread of the deformation. You can also use a parameter map to modulate the amplitude of the deformation across the surface.

Making Waves

There are two ways to create a wave deformation: you can create and apply a wave at the same time or you can create a wave object first and then manually apply a wave operator later.

NoteTo apply a wave deformation to points, clusters, or weight maps, you must use the manual method.

Creating and Applying Waves

If objects are selected when you create a wave control object, the object is created at the object's center and a wave operator is automatically applied. However, this method does not work if points, clusters, or weight maps are selected.

To create and apply a wave to objects

  1. Select one or more objects, branches, or models.

  2. Choose Get Primitive Control Object Wave.

    The wave control object is created (as represented by a wireframe icon in the geometry views) and its property editor opens. The wave object is automatically a child of the deformed object.

    In addition, Wave operators are automatically applied to the objects that were selected.

Applying Waves Manually

If a wave object already exists in your scene, you apply it manually to scene elements. This is the only way to apply wave operators to points, clusters, and weight maps.

To apply a wave to elements

  1. If necessary, create a wave object without applying it to anything by choosing Get Primitive Control Object Wave with nothing selected.

  2. Select one or more objects, branches, models, points, point clusters, or weight maps.

  3. Choose Deform Wave. This command is available under Modify on the Model and Simulate toolbars, as well as under Deform on the Animate toolbar.

  4. Pick the wave object. Wave operators are applied to the selected elements and the Wave Op property editor opens.

Modifying Wave Control Objects

You can use the wave property editor to set the wave's basic characteristics such as its shape and speed — these are described in the sections that follow. This way, as you change the various parameters in the editor, you can see the effect on an object's deformation.

You can also scale, rotate, and translate the wave control object to define its center and the direction of the waves.

Setting the Wave Shape

There are three parameters that control the wave shape: Type, Displacement Direction, and Profile.

Setting the Wave Type

The Type parameter on the General tab of the wave property editor controls how the wave moves through space. There are three options: circular, planar, and spherical. Each type of wave is represented by a different icon in the geometry views and is shown in the following illustrations.

  • Circular: The waves move out from a point in a circular, planar pattern, like those from a pebble dropped in still water.

  • 'Planar: The waves move out from a line in a straight, planar pattern, like waves hitting a beach or a flag fluttering in the wind.

       
  • Spherical: The waves moves out from a point spherically in all directions, like the shock waves of an explosion.

         
     

Setting the Displacement Direction

The Displacement Direction determines which way the points of deformed objects move when they are displaced:

  • Up displaces points along the local Y axis of the wave object.

  • Direction displaces points in the direction in which the wave is moving.

  • Normal displaces each point along the normal of the deformed object at that point.

Setting the Wave Profile

The shape of the wave's displacement is controlled by the Amplitude Profile curve on the Profiles property page of the wave property editor. You can edit the profile using the mouse and the same keyboard commands as the fcurve editor or right-click to display a menu.

Controlling Periodicity

Periodicity allows the wave to repeat continuously. There are two kinds of periodicity:

  • in Space repeats the shape of the wave's profile between the first and last key points indefinitely.

  • in Time repeats the entire wave effect, including the result of Amplitude and Spread as set in the operator's property editor (not the object's).

    The wave deformation begins again after the End frame set on the Time Control tab of the operator's property editor.

Controlling Speed

You can control the velocity and acceleration at which the wave profile moves through space using the Velocity and Acceleration parameters in the wave control object's property editor. You can even use a negative velocity to make the wave move backward.

Controlling Falloff

You can make the strength of the wave effect fall off after a certain vertical distance from the wave control object. The effect decays linearly between the Vertical Falloff Start and End values as measured along the wave's local Y axis.

Transforming the Wave Control Object

Translations and rotations may be applied to wave control objects in the same manner as ordinary objects. The wave's effect on objects changes in the obvious way. For example, if you move a circular wave along a grid, you change the point from which the wave emanates.

You can apply scaling as well. The icon changes shape accordingly, but the wave's effect on objects changes only in the following ways:

  • For scaling in X and Y, the effect appears as if the profile curve were scaled correspondingly.

  • Scaling in Z does not change the effects of circular or spherical waves, but it does change the Z-extents for planar waves. The planar-wave icon makes this quite clear.

Modifying Wave Operators

The wave operator deforms an object or cluster by "attaching" a wave control object. The wave operator is a node in the object's operator stack that controls the parameters that are specific to how the wave affects a particular object, such as the amplitude and spread of the deformation. By default, both the Amplitude and Spread are animated with a function curve.

Note

To make sure that the wave operator gets re-evaluated to update the object's deformation at every frame, at least one of its parameters must be animated. A single keyframe (that is, a flat, constant-value fcurve) is enough.

By default, both Amplitude and Spread are animated, so the wave operator will be re-evaluated unless you remove the animation.

Controlling Amplitude

Amplitude provides an overall scaling factor for the wave profile's height over time. By default it starts at 0, rises sharply to 1, and then decays slowly back to 0. This corresponds to a wave rising rapidly on a surface and then slowly receding back to nothing.

Wave's amplitude diminishes over time.

Controlling Spread

Spread gives an overall inverse scaling factor to the X values of the wave profile. For example, a value of 0.5 stretches the profile by 2 horizontally, which has the effect of spreading the wave.

By default, the spread is the constant value 1. Certain types of waves, such as water waves, spread out as they move. For such waves, you should edit the spread function curve to start at 1 and end at a smaller value such as 0.5.

Wave spreads out over time.

Controlling the Start and End

The options on the Time Control tab of the Wave Op property editor control the time span of the wave effect:

  • Start offset is the first frame for which the wave begins to affect the object.

  • End is the last frame for which the wave affects the object.