NAME

       SbProjector -

       The SbProjector class is the abstract base projector class.

       Projectors are used in the Coin library for mapping 2D coordinates (typically from the
       position of the mouse cursor in the rendering window) to 3D 'world' coordinates.

SYNOPSIS

       #include <Inventor/projectors/SbProjector.h>

       Inherited by SbCylinderProjector, SbLineProjector, SbPlaneProjector, and
       SbSphereProjector.

   Public Member Functions
       virtual SbVec3f project (const SbVec2f &point)=0
       virtual void setViewVolume (const SbViewVolume &vol)
       const SbViewVolume & getViewVolume (void) const
       virtual void setWorkingSpace (const SbMatrix &space)
       const SbMatrix & getWorkingSpace (void) const
       virtual SbProjector * copy (void) const =0
       virtual SbBool tryProject (const SbVec2f &point, const float epsilon, SbVec3f &result)

   Protected Member Functions
       SbProjector (void)
       virtual ~SbProjector ()
       SbLine getWorkingLine (const SbVec2f &point) const
       float findVanishingDistance (void) const
       SbBool verifyProjection (const SbVec3f &projpt) const

   Protected Attributes
       SbViewVolume viewVol
       SbMatrix worldToWorking
       SbMatrix workingToWorld

Detailed Description

       The SbProjector class is the abstract base projector class.

       Projectors are used in the Coin library for mapping 2D coordinates (typically from the
       position of the mouse cursor in the rendering window) to 3D 'world' coordinates.

       Mapping 2D coordinates to 3D coordinates is something which is done extensively in the
       dragger classes, to provide the user with a convenient and natural way of interacting with
       the 3D geometry of scenes.

       For a usage example, see the class documentation for SbSphereSheetProjector.

       The application programmer should normally not need to care about the projector classes,
       unless there are special needs in the application.

       See Also:
           SoDragger

Constructor & Destructor Documentation

   SbProjector::SbProjector (void) [protected]
       The constructor initializes the workingspace matrix to an identity matrix.

   SbProjector::~SbProjector () [inline],  [protected],  [virtual]
       Destructor is protected, as this is an abstract class.

Member Function Documentation

   SbVec3f SbProjector::project (const SbVec2f &point) [pure virtual]
       Project the 2D point from normalized viewport coordinates to a 3D point. The mapping will
       be done in accordance with the type of the projector.

       Implemented in SbCylinderSectionProjector, SbSphereSectionProjector,
       SbCylinderPlaneProjector, SbCylinderSheetProjector, SbSpherePlaneProjector,
       SbLineProjector, SbPlaneProjector, SbSphereSheetProjector, and SbCylinderProjector.

   void SbProjector::setViewVolume (const SbViewVolume &vol) [virtual]
       Set the viewing volume the projections will take place in.

       See Also:
           getViewVolume()

   const SbViewVolume & SbProjector::getViewVolume (void) const
       Return the current viewing volume used by the projections.

       See Also:
           setViewVolume()

   void SbProjector::setWorkingSpace (const SbMatrix &space) [virtual]
       Sets the matrix used for converting from the projector's coordinate system to the world
       coordinate system.

       Reimplemented in SbSphereProjector, and SbCylinderProjector.

   const SbMatrix & SbProjector::getWorkingSpace (void) const
       Returns projector-to-world matrix.

       See Also:
           setWorkingSpace()

   SbProjector * SbProjector::copy (void) const [pure virtual]
       Construct and return a copy of this projector. The caller is responsible for destructing
       the new instance.

       Note that if the Coin library has been built as a DLL under Microsoft Windows and you use
       this method from application code, you must make sure that both the Coin DLL and the
       application executable is using the same instance of a C Run-Time (CRT) library.
       Otherwise, you will get memory heap corruption upon deallocating the returned instances,
       eventually leading to mysterious crashes.

       Implemented in SbCylinderSectionProjector, SbSphereSectionProjector,
       SbCylinderPlaneProjector, SbCylinderSheetProjector, SbSpherePlaneProjector,
       SbLineProjector, SbPlaneProjector, and SbSphereSheetProjector.

   SbBool SbProjector::tryProject (const SbVec2f &point, const floatepsilon, SbVec3f &result)
       [virtual]
       Try projecting the 2D point from normalized viewport coordinates to a 3D point. The
       mapping will be done in accordance with the type of the projector.

       If the projection can't be done safely (for instance when the projection plane or line is
       parallel to the view volume projection), this function should return FALSE.

       Default implementation will call project() and always return TRUE, but subclasses can
       override this behavior to support safe projections.

       Since:
           Coin 3.0

       Reimplemented in SbLineProjector, and SbPlaneProjector.

   SbLine SbProjector::getWorkingLine (const SbVec2f &point) const [protected]
       From the 2D point in normalized screenspace coordinates, calculate the line passing
       through the scene.

       Typically used for tracking intersection points for the mouse cursor.

   float SbProjector::findVanishingDistance (void) const [protected]
       Finds the unit cube vanishing distance for the current projector view volume. The view
       volume must be a perspective view volume.

       This method was not part of the Inventor v2.1 API, and is an extension specific to Coin.

       Since:
           Coin 1.1

   SbBool SbProjector::verifyProjection (const SbVec3f &projpt) const [protected]
       Verifies that projpt is a valid projection for the current view volume. For perspective
       view volumes, it does this by checking that the projection point is in front of the eye
       plane. For orthographic projections, this method always returns TRUE.

       This method was not part of the Inventor v2.1 API, and is an extension specific to Coin.

       Since:
           Coin 1.1

Member Data Documentation

   SbProjector::viewVol [protected]
       The viewVol definition.

   SbProjector::worldToWorking [protected]
       The matrix which converts from world coordinates to coordinates in the projector's local
       coordinate system.

   SbProjector::workingToWorld [protected]
       The matrix which converts from coordinates in the projector's local coordinate system to
       world coordinates.

Author

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