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SoNurbsSurface Class Reference

The SoNurbsSurface class is used to render smooth surfaces.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". More...

#include <Inventor/nodes/SoNurbsSurface.h>

Inheritance diagram for SoNurbsSurface:
SoShape SoNode SoFieldContainer SoBase

List of all members.

Public Member Functions

 SoNurbsSurface (void)
virtual void GLRender (SoGLRenderAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
void sendPrimitive (SoAction *, SoPrimitiveVertex *)

Static Public Member Functions

static void initClass (void)

Public Attributes

SoSFInt32 numUControlPoints
SoSFInt32 numVControlPoints
SoSFInt32 numSControlPoints
SoSFInt32 numTControlPoints
SoMFFloat uKnotVector
SoMFFloat vKnotVector
SoMFFloat sKnotVector
SoMFFloat tKnotVector

Protected Member Functions

virtual ~SoNurbsSurface ()
virtual void generatePrimitives (SoAction *action)
virtual void computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center)
SoDetailcreateTriangleDetail (SoRayPickAction *action, const SoPrimitiveVertex *v1, const SoPrimitiveVertex *v2, const SoPrimitiveVertex *v3, SoPickedPoint *pp)

Friends

class SoNurbsSurfaceP

Detailed Description

The SoNurbsSurface class is used to render smooth surfaces.

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 surface 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 basic usage example:

  #Inventor V2.1 ascii

  ShapeHints {
    vertexOrdering COUNTERCLOCKWISE
  }

  Coordinate3 {
     point [ 
       -3 -3 -3, -3 -1 -3, -3  1 -3, -3  3 -3,
       -1 -3 -3, -1 -1  3, -1  1  3, -1  3 -3,
        1 -3 -3,  1 -1  3,  1  1  3,  1  3 -3,
        3 -3 -3,  3 -1 -3,  3  1 -3,  3  3 -3
      ]
  }

  NurbsSurface {
     numUControlPoints 4
     numVControlPoints 4
     uKnotVector [ 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0 ]
     vKnotVector [ 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0 ]
  }
nurbssurface.png

FILE FORMAT/DEFAULTS:


Constructor & Destructor Documentation

SoNurbsSurface::SoNurbsSurface ( void  )
SoNurbsSurface::~SoNurbsSurface ( ) [protected, virtual]

Destructor.


Member Function Documentation

void SoNurbsSurface::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 SoNurbsSurface::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.

References SoAction::getState(), and SoShape::shouldGLRender().

void SoNurbsSurface::rayPick ( SoRayPickAction action) [virtual]

Calculates picked point based on primitives generated by subclasses.

Reimplemented from SoShape.

References SoAction::getState(), SoState::pop(), SoDebugError::postWarning(), SoState::push(), SoFieldContainer::set(), and SoShape::shouldRayPick().

void SoNurbsSurface::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 SoNurbsSurface::sendPrimitive ( SoAction ,
SoPrimitiveVertex  
)

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 SoNurbsSurface::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 SoNurbsSurface::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.

References SbBox3f::extendBy(), SoAction::getState(), SbBox3f::makeEmpty(), numUControlPoints, and numVControlPoints.

SoDetail * SoNurbsSurface::createTriangleDetail ( SoRayPickAction action,
const SoPrimitiveVertex v1,
const SoPrimitiveVertex v2,
const SoPrimitiveVertex v3,
SoPickedPoint pp 
) [protected, virtual]

Will create triangle 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

Number of control points in the U direction.

Referenced by computeBBox(), and SoNurbsSurface().

Number of control points in the V direction.

Referenced by computeBBox(), and SoNurbsSurface().

Number of control points in the S direction.

Referenced by SoNurbsSurface().

Number of control points in the T direction.

Referenced by SoNurbsSurface().

The Bezier knot vector for the U direction.

Referenced by SoNurbsSurface().

The Bezier knot vector for the V direction.

Referenced by SoNurbsSurface().

The Bezier knot vector for the S direction.

Referenced by SoNurbsSurface().

The Bezier knot vector for the T direction.

Referenced by SoNurbsSurface().


The documentation for this class was generated from the following files:

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