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SoNurbsSurface.3coin2

Langue: en

Version: 380925 (fedora - 01/12/10)

Section: 3 (Bibliothèques de fonctions)

Sommaire

NAME
SYNOPSIS
Detailed Description
Constructor & Destructor Documentation
- SoNurbsSurface::SoNurbsSurface (void)Constructor.
- SoNurbsSurface::~SoNurbsSurface () [protected, virtual]Destructor.
Member Function Documentation
Member Data Documentation
Author

NAME

SoNurbsSurface -

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'.

SYNOPSIS

#include <Inventor/nodes/SoNurbsSurface.h>

Inherits SoShape.

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)

SoDetail * createTriangleDetail (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.

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 ]
   }

FILE FORMAT/DEFAULTS:

     NurbsSurface {
         numUControlPoints 0
         numVControlPoints 0
         numSControlPoints 0
         numTControlPoints 0
         uKnotVector 0
         vKnotVector 0
         sKnotVector 0
         tKnotVector 0
     }

Constructor & Destructor Documentation

SoNurbsSurface::SoNurbsSurface (void)Constructor.

References numSControlPoints, numTControlPoints, numUControlPoints, numVControlPoints, sKnotVector, tKnotVector, uKnotVector, and vKnotVector.

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

SoSFInt32 SoNurbsSurface::numUControlPointsNumber of control points in the U direction.

Referenced by computeBBox(), and SoNurbsSurface().