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VRML Script Tutorial
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VRML Interactive Tutorial

Introduction
VRML File Structure
Drawing: Shape node
Geometry Nodes:
Box
Sphere
Cone
Cylinder
PointSet
IndexedLineSet
IndexedFaceSet
Extrusion
ElevationGrid
Example: Chessboard
Text
FontStyle
Appearance
Material
Textures
Image Texture
Movie Texture
Pixel Texture
Texture Coordinate
Texture Transform
Let there be Light
Directional Light
Point Light
Spot Light
Materials with Colored Lights
Hierarchical Node Structures
Group
Transform
Collision
Anchor
Billboard
Switch
Inlining Files
Defining and Instancing Nodes
Defining Levels of Detail
Events in VRML
Creating Paths between events: ROUTE
Generating Events based on Timers or User Actions
Timers
Touch Sensor
Visibility Sensor
Dragging Sensors
Plane Sensor
Sphere Sensor
Cylinder Sensor
Proximity Sensors
Example: Proximity sensor
Interpolators
Color
Coordinate
Normal
Orientation
Position
Scalar
Example
Let the Music Play
Sound
AudioClip
Bindable Nodes
Who Am I: NavigationInfo
Where Am I: ViewPoint
Adding Realism to the world
Background
Fog
Information about your world
WorldInfo
Definition for Auxiliary Nodes
Coordinate
Color
Normal

CoordinateInterpolator


The CoordinateInterpolator node is an interpolator which takes a list of 3D coordinate values in the field keyValue. As opposed to the PositionInterpolator node, which provides a way to translate a shape as a whole along a predefined path, the CoordinateInterpolator allows you to control each of the points defined in a Coordinate node (Coordinate node appears inside of a IndexedFaceSet, IndexedLineSet, or PointSet).

For a list of the events of this node see interpolator.

Syntax:
CoordinateInterpolator {
key [ ]
keyValue[ ]
}


The eventOut fraction_changed of this node can be routed to the eventIn set_point of a Coordinate node defined in any of the following nodes: IndexedFaceSet, IndexedLineSet, or PointSet.

The number of keyValue entries must be equal to the number of keys provided times the number of points specified in the field coord, i.e. for each key specified there must be as many values as points in the coord field to which the fraction_changed eventOut is routed to. Note that by value it is meant a 3D coordinate.

This interpolator can be used to create morphs between shapes, moving lines or points.

A complete example is now presented. A single square face is drawn in an IndexedFaceSet. The interpolator will be used to morph this square face to a trapezoid face, and back again. The cycle is repeated forever.

First one needs the to define a Group with a IndexedFaceSet, a TimeSensor, and a CoordinateInterpolator.



Example:

#VRML V2.0 utf8

Group {
children [
    Shape{ appearance Appearance { material Material { }}
      geometry IndexedFaceSet {
        coord DEF co Coordinate {
          point [-1 -1 0, 1 -1 0, 1 1 0, -1 1 0 ]
        }
        coordIndex [0 1 2 3]
      }
    }
    DEF ci CoordinateInterpolator {
      key [0 0.5 1]
      keyValue [-1 -1 0, 1 -1 0, 1 1 0, -1 1 0,
        -1 -1 0, 1 -0.5 0, 1 0.5 0, -1 1 0,
        -1 -1 0, 1 -1 0, 1 1 0, -1 1 0]
      }
DEF ts TimeSensor {
cycleInterval 2
loop TRUE
}
]
}


Now the only thing which is missing is routing the events.

We need to get the eventOut fraction_changed generated by the TimeSensor. This event outputs a value between 0 and 1. We can use this value to set a key for the interpolator by routing the fraction_changed eventOut from the TimeSensor to the set_fraction eventIn from the interpolator.

A new fraction being set in an interpolator causes the keyValue to be changed. As a consequence the interpolator will generate the fraction_changed eventOut. Because the interpolator used is a CoordinateInterpolator, this event outputs a list of 3D coordinate value.

Finally we use this eventOut to change the Coordinate node inside the IndexedFaceSet node. Because the point field in a Coordinate node is an exposed field we can use the eventIn set_point to change it. To do this we route the fraction_changed eventOut of the CoordinateInterpolator to the set_point eventIn of the Coordinate node.

The ROUTE statements to do this are:
ROUTE ts.fraction_changed TO ci.set_fraction
ROUTE ci.value_changed TO co.set_point
Note that the nodes being routed are given a name using the DEF statement. This is because a name is required in a ROUTE statement.



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