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OpenGL 1.1 for AIX: Reference Manual

gluLoadSamplingMatrices Subroutine


Loads non-uniform rational B-spline (NURBS) sampling and culling matrices.


OpenGL C bindings library: libGL.a

C Syntax

void gluLoadSamplingMatrices(GLUnurbsObj *nobj, 
   const GLfloat ModelMatrix[16], 
   const GLfloat ProjectionMatrix[16], 
   const GLint Viewport[4])


The gluLoadSamplingMatrices subroutine uses the ModelMatrix, ProjectionMatrix, and Viewport parameters to recompute the sampling and culling matrices stored in the nobj parameter. The sampling matrix determines how finely a NURBS surface or curve must be tessellated to satisfy the sampling tolerance (as determined by the GLU_SAMPLING_TOLERANCE property). The culling matrix determines whether a NURBS curve or surface should be culled before rendering (when the GLU_CULLING property is turned on).

Use of the gluLoadSamplingMatrices subroutine is necessary only if the GLU_AUTO_LOAD_MATRIX property is turned off. (See the gluNurbsProperty subroutine for information on adjusting properties in a NURBS object.) Leaving the GLU_AUTO_LOAD_MATRIX property turned on causes performance slowdown since it necessitates a round-trip to the OpenGL server to fetch the current values of the modelview matrix, projection matrix, and viewport.


nobj Specifies the NURBS object created with the gluNewNurbsRenderer subroutine.
ModelMatrix Specifies a modelview matrix, such as from a glGetFloatv call.
ProjectionMatrix Specifies a projection matrix, such as from a glGetFloatv call.
Viewport Specifies a viewport, such as from a glGetIntegerv call.


/usr/include/GL/gl.h Contains C language constraints, variable type definitions, and ANSI function prototypes for OpenGL.

Related Information

The gluGetNurbsProperty subroutine, gluNewNurbsRenderer subroutine, gluNurbsProperty subroutine.

OpenGL Overview.

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