SoNurbsSurface Class Reference
[Shapes]

NURBS surface shape node. More...

#include <Inventor/nodes/SoNurbsSurface.h>

Inheritance diagram for SoNurbsSurface:

Public Member Functions
virtual SoType	getTypeId () const
	SoNurbsSurface ()
Static Public Member Functions
static SoType	getClassTypeId ()
Public Attributes
SoSFInt32	numUControlPoints
SoSFInt32	numVControlPoints
SoSFInt32	numSControlPoints
SoSFInt32	numTControlPoints
SoMFFloat	uKnotVector
SoMFFloat	vKnotVector
SoMFFloat	sKnotVector
SoMFFloat	tKnotVector

Detailed Description

NURBS surface shape node.

This shape node represents a NURBS surface based on the node's knot vectors and on control points constructed from the current coordinates. The current coordinates are used in row-major order (the V direction corresponds to the rows). The number of coordinates used is determined by the numUControlPoints and numVControlPoints fields. The uKnotVector and vKnotVector fields contain floating point arrays of non-decreasing values.

The order of the surface in the U and V directions is defined as the number of knots minus the number of control points in the particular direction. The largest order allowed for a NURBS surface is 8.

The control points of the NURBS surface are transformed by the current cumulative transformation. The surface is drawn with the current light model and drawing style. The coordinates, normals, and texture coordinates of a surface are generated, so you cannot bind explicit normals or texture coordinates to a NURBS surface. The first material in the state is applied to the entire surface.

The surface is trimmed according to the currently defined profile's curves.

When default texture coordinates are applied to a NURBS surface, the edges of the texture square are stretched to fit the surface. The axes of the texture are called S and T; S is horizontal and T is vertical. The axes of the NURBS surface are called U and V; U is horizontal and V is vertical. You can also define texture coordinates explicitly with the S,T location point, the knot vectors, and the current texture coordinates. The number of texture coordinates used is determined by the numSControlPoints and numTControlPoints fields.

The approximation of the surface by polygons is affected by the current complexity value.

NOTE:

If OIV_FORCE_GLU_NURB is set to 1, GLU is used to render textured and untextured NURBS surfaces. Performance will be much lower.

GLU is also used if SoComplexity::type == SCREEN_SPACE. Be careful as tessellation may take a significant amount of time when the camera is very close to the surface.

Otherwise (i.e., if SoComplexity::type == OBJECT_SPACE and OIV_FORCE_GLU_NURB is not set), an Open Inventor NURBS algorithm is used.

The fields numSControlPoints, numTControlPoints, sKnotVector and tKnotVector are not used unless OIV_FORCE_GLU_NURB is set to 1.

FILE FORMAT/DEFAULT

numUControlPoints	0
numVControlPoints	0
numSControlPoints	0
numTControlPoints	0
uKnotVector	0
vKnotVector	0
sKnotVector	0
tKnotVector	0

ACTION BEHAVIOR

SoGLRenderAction

SoRayPickAction
Picks the surface based on the current coordinates and transformation.

SoGetBoundingBoxAction
Computes the bounding box that encloses all control points of the surface with the current transformation applied to them. Sets the center to the average of the control points.

SoCallbackAction
If any triangle callbacks are registered with the action, they will be invoked for each successive triangle approximating the surface.