This property node defines a coordinate projection that will be applied to all subsequent shapes in the scene graph. Coordinate transform nodes like OIV.Inventor.Nodes.SoTransform can only apply transforms that can be expressed as a matrix. A coordinate projection can be any algorithm that takes a coordinate and returns a different coordinate. This is particularly useful for geospatial coordinate systems (see OIV.Inventor.Nodes.SoGeoProjection), but is also useful for using spherical, cylindrical and other coordinate systems directly.

This node works together with projection classes derived from the OIV.Inventor.Projection.SbProjection class. The projection classes implement the projection computations applied to 3D points. Applications can create new subclasses of OIV.Inventor.Projection.SbProjection.

To use a specific projection, call OIV.Inventor.Nodes.SoProjection.SetProjection(OIV.Inventor.Projection.SbProjection) with an instance of the OIV.Inventor.Projection.SbProjection class. Each instance of OIV.Inventor.Nodes.SoProjection can also store a list of projections, each one associated with a unique id. This is convenient for switching between different geospatial projections. Changing the OIV.Inventor.Nodes.SoProjection.m_projTypeId value activates the projection registered with the corresponding id.

The default projection is spherical coordinates (OIV.Inventor.Projection.SbSphericalProjection).

The projection classes will use the string parameters and float parameters in the fields OIV.Inventor.Nodes.SoProjection.m_parameters and OIV.Inventor.Nodes.SoProjection.m_floatParameters respectively. See the projection class documentation for relevant parameters.

Normal vectors

• If no normal vectors are given for the geometry (and normal vectors are needed), Open Inventor will automatically compute normal vectors using the projected vertices, i.e. the coordinates after projection has been applied. This is usually the desired result.

• If normal vectors are specified for the geometry, they are not projected. Therefore normal vectors must be specified in post-projection (world) coordinates.

LIMITATIONS

• Shapes The following shapes are not supported by OIV.Inventor.Nodes.SoProjection:

  • Text nodes (OIV.Inventor.Nodes.SoAnnoText3, OIV.Inventor.Nodes.SoAsciiText, OIV.Inventor.Nodes.SoText2, OIV.Inventor.Nodes.SoText3 )

  • OIV.Inventor.Nodes.SoCylinder, OIV.Inventor.Nodes.SoCube, OIV.Inventor.Nodes.SoCone

  • All classes inheriting from OIV.Inventor.Nodes.SoAlgebraicShape

  • OIV.Inventor.Nodes.SoImage

  • NURBS shapes

  • All VolumeViz shapes except

    • OIV.VolumeViz.Nodes.SoVolumeRender with some limitations (see OIV.VolumeViz.Nodes.SoVolumeRender doc for details)

    • Volume geometry nodes (e.g. OIV.VolumeViz.Nodes.SoVolumeIndexedFaceSet)

• Transform nodes The projection mechanism is not compatible with transform and manipulator nodes. Using nodes derived from OIV.Inventor.Nodes.SoTransformation, for example OIV.Inventor.Nodes.SoTransform or OIV.Inventor.Manips.SoTabBoxManip will give unexpected results. To apply a transformation matrix to projected shapes, set the OIV.Inventor.Nodes.SoProjection.m_matrix field to the expected value. Shape vertices will be multiplied by the matrix before being projected.

• Draggers Because draggers are composed with OIV.Inventor.Nodes.SoTransformation nodes, they can't be projected using an OIV.Inventor.Nodes.SoProjection node.

• Memory Because shape coordinates must be duplicated, memory consumption will increase when using projections.

• Picking Projection is not applied when doing picking (OIV.Inventor.Actions.SoRayPickAction). Results may be incorrect.

FILE FORMAT/DEFAULT

Projection {

parameters	""
matrix	identity
isOn	true
floatParameters	1
projTypeId	0

}

ACTION BEHAVIOR

Sets: OIV.Inventor.Elements.SoCoordinateElement

Reference