gluLoadSamplingMatrices function

The gluLoadSamplingMatrices function loads Non-Uniform Rational B-Spline (NURBS) sampling and culling matrices.

Syntax

void WINAPI gluLoadSamplingMatrices(
         GLUnurbs *nobj,
   const GLfloat  modelMatrix[16],
   const GLfloat  projMatrix[16],
   const GLint    viewport[4]
);

Parameters

nobj

The NURBS object (created with gluNewNurbsRenderer).

modelMatrix

A modelview matrix (as from a glGetFloatv call).

projMatrix

A projection matrix (as from a glGetFloatv call).

viewport

A viewport (as from a glGetIntegerv call).

Return value

This function does not return a value.

Remarks

The gluLoadSamplingMatrices function 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).

The gluLoadSamplingMatrices function 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, doing so necessitates a round trip to the OpenGL server to get the current values of the modelview matrix, projection matrix, and viewport.)

Requirements

See also

glGetFloatv

glGetIntegerv

gluGetNurbsProperty

gluNewNurbsRenderer