gluLoadSamplingMatrices — load NURBS sampling and culling matrices
void gluLoadSamplingMatrices( | GLUnurbs* nurb, |
const GLfloat * model, | |
const GLfloat * perspective, | |
const GLint * view) ; |
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.)
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