gluLoadSamplingMatrices

gluLoadSamplingMatrices: load NURBS sampling and culling matrices.

C Specification | Parameters | Description | See Also

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).

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.)