gluLoadSamplingMatrices.3G man page
gluLoadSamplingMatrices — load NURBS sampling and culling matrices
void gluLoadSamplingMatrices(GLUnurbs* nurb, const GLfloat * model, const GLfloat * perspective, const GLint * view);
Specifies the NURBS object (created with gluNewNurbsRenderer()).
Specifies a modelview matrix (as from a glGetFloatv() call).
Specifies a projection matrix (as from a glGetFloatv() call).
Specifies a viewport (as from a glGetIntegerv() call).
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.)
gluGetNurbsProperty(), gluNewNurbsRenderer(), gluNurbsProperty()
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