Introducing Animations

Motivation

• Nodes like Billboard and Anchor have built-in behavior
• You can create your own behaviors to make shapes move, rotate, scale, blink, and more
• We need a means to trigger, time, and respond to a sequence of events in order to provide better user/world interactions

Building animation circuits

Almost every node can be a component in an animation circuit

• Nodes act like virtual electronic parts
• Nodes can send and receive events
• Wired routes connect nodes together

An event is a message sent between nodes

• A data value (such as a translation)
• A time stamp (when did the event get sent)

Examples

To spin a shape:

• Connect a node that sends rotation events to a Transform node’s rotation field

To blink a shape:

• Connect a node that sends color events to a Material node’s diffuseColor field

Routing events

To set up an animation circuit, you need three things:

1. A node which sends events
   • The node must be named with DEF
2. A node which receives events
   • The node must be named with DEF
3. A route connecting them

Using node inputs and outputs

Every node has fields, inputs, and outputs:

• initializeOnly: A stored value
• inputOnly: An input
• outputOnly: An output

An inputOutput field is a short-hand for a initializeOnly, inputOnly, and outputOnly

Sample inputs

A Transform node has these input fields:

• set_translation
• set_rotation
• set_scale

A Material node has these input fields:

• set_diffuseColor
• set_emissiveColor
• set_transparency

Sample outputs

An OrientationInterpolator node has this output field:

• value_changed to send rotation values

A PositionInterpolator node has this output field:

• value_changed to send position (translation) values

A TimeSensor node has this output field:

• time to send time values

Syntax: ROUTE

A ROUTE statement connects two nodes together using

• The sender’s node name and output field name
• The receiver’s node name and input field name

XML Encoding

<ROUTE fromNode='MySender' fromField='rotation_changed' toNode='MyReceiver' toField='set_rotation'/>

Classic VRML Encoding

ROUTE MySender.rotation_changed TO MyReceiver.set_rotation

ROUTE and TO must be in upper-case

Field data types

Sender and receiver field data types must match!

Data types have names with a standard format, such as:

• SFString,SFRotation, or MFColor

Character	Values
1	**S:** Single value **M:** Multiple values
2	Always an **F** (for field)
remainder	Name of data type, such as **String, Rotation,** or **Color**

Data type	Meaning
SFBool, MFBool	Boolean, true or false value
SFColor, MFColor	RGB color value
SFColorRGBA, MFColorRGBA	RGBA color value
SFDouble, MFDouble	Double precision floating point value
SFFloat, MFFloat	Floating point value
SFImage, MFImage	Image value
SFInt32, MFInt32	Integer value
SFMatrix3d, MFMatrix3d	3×3 matrix value, double precision
SFMatrix3f, MFMatrix3f	3×3 matrix value
SFMatrix4d, MFMatrix4d	4×4 matrix value, double precision
SFMatrix4f, MFMatrix4f	4×4 matrix value
SFNode, MFNode	Node value
SFRotation, MFRotation	Rotation value
SFString, MFString	Text string value
SFTime, MFTime	Time value
SFVec2d, MFVec2d	XY floating point value, double precision
SFVec2f, MFVec2f	XY floating point value
SFVec3d, MFVec3d	XYZ floating point value, double precision
SFVec3f, MFVec3f	XYZ floating point value
SFVec4d, MFVec4d	XYZW floating point value, double precision
SFVec4f, MFVec4f	XYZW floating point value

Following naming conventions

Most nodes have inputOutput fields.

If the inputOutput field name is xxx, then:

• set_xxx is an input to set the field
• xxx_changed is an output that sends when the field changes
• The set_ and _changed sufixes are optional but recommended for clarity

The Transform node has:

• rotation field
• set_rotation input
• rotation_changed output

A sample animation

XML Encoding

<TouchSensor DEF='Touch'/>

<TimeSensor DEF='Timer1' ... />

<OrientationInterpolator DEF='Rot1' ... />

<Transform DEF='Frame1'>
  <Shape><!-- ... --></Shape>
</Transform>

<ROUTE fromNode='Touch' fromField='touchTime' toNode='Timer1' toField='set_startTime'/>
<ROUTE fromNode='Timer1' fromField='fraction_changed' toNode='Rot1' toField='set_fraction'/>
<ROUTE fromNode='Rot1' fromField='value_changed' toNode='Frame1' toField='set_rotation'/>

Classic VRML Encoding

DEF Touch TouchSensor { }

DEF Timer1 TimeSensor { ... }

DEF Rot1 OrientationInterpolator { ... }

DEF Frame1 Transform {
  children [
    Shape { ... }
  ]
}

ROUTE Touch.touchTime         TO Timer1.set_startTime
ROUTE Timer1.fraction_changed TO Rot1.set_fraction
ROUTE Rot1.value_changed      TO Frame1.set_rotation

Using multiple routes

You can have fan-out

• Multiple routes out of the same sender

You can have fan-in

• Multiple routes into the same receiver

Summary

• Connect senders to receivers using routes
• input fields are inputs, and output fields are outputs
• A route names the sender.output, and the receiver.input
  • Data types must match
• You can have multiple routes into or out of a node