gluLoadSamplingMatrices - load NURBS sampling and culling matrices
void gluLoadSamplingMatrices( GLUnurbsObj *nobj, const GLfloat modelMatrix[16], const GLfloat projMatrix[16], const GLint viewport[4]); )
nobj Specifies the NURBS object (created with gluNewNurbsRenderer). modelMatrix Specifies a modelview matrix (as from a glGetFloatv call). projMatrix Specifies a projection matrix (as from a glGetFloatv call). viewport; Specifies a viewport (as from a glGetIntegerv call).
gluLoadSamplingMatrices uses modelMatrix, projMatrix, and viewport; to recompute the sampling and culling matrices stored in nobj. 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 OpenGL server is needed to fetch the current values of the modelview matrix, projection matrix, and viewport.)
gluGetNurbsProperty, gluNewNurbsRenderer, gluNurbsProperty
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Last Edited: Mon, May 22, 1995