OrientationInterpolatorEx Node - Interpolator Nodes in Cortona - VRML Extensions - Cortona VRML Client - Products - Developer Zone


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OrientationInterpolatorEx Node

The OrientationInterpolatorEx node interpolates among a list of rotation values using a specified interpolation method. This node extends the standard OrientationInterpolator node.

EXTERNPROTO OrientationInterpolatorEx [ 
  eventIn         SFFloat      set_fraction               # (-inf,inf)
  exposedField    MFFloat      key             []         # (-inf,inf)
  exposedField    MFRotation   keyValue        []         # [-1,1],(-inf,inf)
  exposedField    SFString     type            "LINEAR"  
  eventOut        SFRotation   value_changed
]
[
  "urn:inet:parallelgraphics.com:cortona:OrientationInterpolatorEx"
  "http://www.parallelgraphics.com/vrml/proto/Cortona/extensions.wrl
  #OrientationInterpolatorEx"
]

The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR" (slerp) and "SPLINE" (squad):

Value of the type field Interpolation
"CONSTANT" The orientation value remains fixed until the next keyframe. No interpolation is performed.

"LINEAR" The value of orientation is interpolated uniformly along a geodesic in the surface of the 3-sphere between the previous and the next keyframe values. This method is often referred to as SLERP (Spherical-Linear intERPolation). That is how the interpolation is made by the OrientationInterpolator node.

"SPLINE" The value of orientation is interpolated between keyframe values using cubic Hermite polynoms. This method is referred to as SQUAD (Spherical QUADrilateral interpolation). Unlike SLERP, the transition between adjacent intervals at keyframes is smooth.

Notes (for the "SPLINE" interpolation type):

Linear interpolation is used instead of cubic interpolation if the number of keyframes is less than 4.

If the value of the first keyframe coincides with the value of the last keyframe, the cubic spline is "closed".

Definitions of the other fields and events of the OrientationInterpolatorEx node are similar to the corresponding definitions for the OrientationInterpolator node.