Provided by: libcoin60-doc_3.1.3-2_all bug

NAME

       SoNurbsCurve -

       The SoNurbsCurve class is a node for representing smooth curves.

       A general explanation of NURBS is beyond the scope of the Coin documentation. For detailed
       information, refer to the specialized literature on the topic (for example 'An
       Introduction to NURBS: With
         Historical Perspective' by David F. Rogers). A basic overview of curve and surface
       rendering using NURBS can be found in chapter 8 of 'The Inventor Mentor'.

SYNOPSIS

       #include <Inventor/nodes/SoNurbsCurve.h>

       Inherits SoShape.

   Public Member Functions
       SoNurbsCurve (void)
       virtual void GLRender (SoGLRenderAction *action)
       virtual void rayPick (SoRayPickAction *action)
       virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
       virtual void getBoundingBox (SoGetBoundingBoxAction *action)
       void sendPrimitive (SoAction *, SoPrimitiveVertex *)

   Static Public Member Functions
       static void initClass (void)

   Public Attributes
       SoSFInt32 numControlPoints
       SoMFFloat knotVector

   Protected Member Functions
       virtual ~SoNurbsCurve ()
       virtual void generatePrimitives (SoAction *action)
       virtual void computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center)
       virtual SoDetail * createLineSegmentDetail (SoRayPickAction *action, const
           SoPrimitiveVertex *v1, const SoPrimitiveVertex *v2, SoPickedPoint *pp)

Detailed Description

       The SoNurbsCurve class is a node for representing smooth curves.

       A general explanation of NURBS is beyond the scope of the Coin documentation. For detailed
       information, refer to the specialized literature on the topic (for example 'An
       Introduction to NURBS: With
         Historical Perspective' by David F. Rogers). A basic overview of curve and surface
       rendering using NURBS can be found in chapter 8 of 'The Inventor Mentor'.

       Note that knot values should be specified as [0, 1, 2,..., a] rather than [0, 1/a,
       2/a,..., 1] to avoid tesselation errors due to floating point precision problems. (Even if
       the rendered curve looks correct, such issues might surface when e.g. doing picking, since
       the tesselated representation used internally is not the same as the one you see rendered
       by OpenGL on-screen.)

       A small usage example (drawing a circle using a rational curve):

         #Inventor V2.1 ascii

         Coordinate4 {
            point [
              0.0 -5.0     0.0 1.0,
              2.5 -2.5     0.0 0.5,
              2.5 -0.66987 0.0 1.0,
              0.0  1.94013 0.0 0.5,
             -2.5 -0.66987 0.0 1.0,
             -2.5 -2.5     0.0 0.5,
              0.0 -5.0     0.0 1.0
            ]
         }

         NurbsCurve {
            numControlPoints 7
            knotVector [ 0, 0, 0, 1, 1, 2, 2, 3, 3, 3 ]
         }

         # debug: show all the control points
         BaseColor { rgb 1 1 0 }
         DrawStyle { pointSize 3 }
         PointSet { numPoints 7 }

       FILE FORMAT/DEFAULTS:

           NurbsCurve {
               numControlPoints 0
               knotVector 0
           }

Constructor & Destructor Documentation

   SoNurbsCurve::SoNurbsCurve (void) Constructor.
   SoNurbsCurve::~SoNurbsCurve () [protected, virtual] Destructor.

Member Function Documentation

   void SoNurbsCurve::initClass (void) [static] Sets up initialization for data common to all
       instances of this class, like submitting necessary information to the Coin type system.
       Reimplemented from SoShape.

   void SoNurbsCurve::GLRender (SoGLRenderAction *action) [virtual] Action method for the
       SoGLRenderAction.
       This is called during rendering traversals. Nodes influencing the rendering state in any
       way or who wants to throw geometry primitives at OpenGL overrides this method.

       Reimplemented from SoShape.

   void SoNurbsCurve::rayPick (SoRayPickAction *action) [virtual] Calculates picked point based
       on primitives generated by subclasses.
       Reimplemented from SoShape.

   void SoNurbsCurve::getPrimitiveCount (SoGetPrimitiveCountAction *action) [virtual] Action
       method for the SoGetPrimitiveCountAction.
       Calculates the number of triangle, line segment and point primitives for the node and adds
       these to the counters of the action.

       Nodes influencing how geometry nodes calculates their primitive count also overrides this
       method to change the relevant state variables.

       Reimplemented from SoShape.

   void SoNurbsCurve::getBoundingBox (SoGetBoundingBoxAction *action) [virtual] Redefined to
       notify open caches that this shape contains lines.
       Reimplemented from SoShape.

   void SoNurbsCurve::sendPrimitive (SoAction *a, SoPrimitiveVertex *p) This method is part of
       the original SGI Inventor API, but not implemented in Coin, as it looks like a method that
       should probably have been private in Open Inventor.
   void SoNurbsCurve::generatePrimitives (SoAction *action) [protected, virtual] The method
       implements action behavior for shape nodes for SoCallbackAction. It is invoked from
       SoShape::callback(). (Subclasses should not override SoNode::callback().)
       The subclass implementations uses the convenience methods SoShape::beginShape(),
       SoShape::shapeVertex(), and SoShape::endShape(), with SoDetail instances, to pass the
       primitives making up the shape back to the caller.

       Implements SoShape.

   void SoNurbsCurve::computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center) [protected,
       virtual] Calculates the bounding box of all control points, and sets the center to the
       average of these points.
       Implements SoShape.

   SoDetail * SoNurbsCurve::createLineSegmentDetail (SoRayPickAction *action, const
       SoPrimitiveVertex *v1, const SoPrimitiveVertex *v2, SoPickedPoint *pp) [protected,
       virtual] Will create line detail for a SoPickedPoint. This method will only be called
       internally, when generatePrimitives() is used for picking (SoShape::rayPick() is not
       overridden).
       This method returns NULL in Open Inventor, and subclasses will need to override this
       method to create details for a SoPickedPoint.

       This is not necessary with Coin. Of course, if you choose to override it, it will work in
       the same way as Open Inventor.

       For this to work, you must supply a face or line detail when generating primitives. If you
       supply NULL for the detail argument in SoShape::beginShape(), you'll have to override this
       method.

       Reimplemented from SoShape.

Member Data Documentation

   SoSFInt32 SoNurbsCurve::numControlPoints Number of control points to use in this NURBS curve.
   SoMFFloat SoNurbsCurve::knotVector The knot vector.
       Values should be specified as [0, 1, 2,..., a] rather than [0, 1/a, 2/a,..., 1] to avoid
       tesselation errors due to floating point precision problems.

Author

       Generated automatically by Doxygen for Coin from the source code.