Name

gluLoadSamplingMatrices — load NURBS sampling and culling matrices

C Specification

void gluLoadSamplingMatrices(GLUnurbs* nurb,
 const GLfloat * model,
 const GLfloat * perspective,
 const GLint * view);
 

Parameters

nurb

Specifies the NURBS object (created with gluNewNurbsRenderer).

model

Specifies a modelview matrix (as from a glGetFloatv call).

perspective

Specifies a projection matrix (as from a glGetFloatv call).

view

Specifies a viewport (as from a glGetIntegerv call).

Description

gluLoadSamplingMatrices uses model, perspective, and view to recompute the sampling and culling matrices stored in nurb. The sampling matrix determines how finely a NURBS curve or surface must be tessellated to satisfy the sampling tolerance (as determined by the GLU_SAMPLING_TOLERANCE property). The culling matrix is used in deciding if a NURBS curve or surface should be culled before rendering (when the GLU_CULLING property is turned on).

gluLoadSamplingMatrices is necessary only if the GLU_AUTO_LOAD_MATRIX property is turned off (see gluNurbsProperty). Although it can be convenient to leave the GLU_AUTO_LOAD_MATRIX property turned on, there can be a performance penalty for doing so. (A round trip to the GL server is needed to fetch the current values of the modelview matrix, projection matrix, and viewport.)

See Also

gluGetNurbsProperty, gluNewNurbsRenderer, gluNurbsProperty

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.