HP b2600 Reference Manual page 419

T
gluTessProperty
Is a boolean value ("value" should be set to GL_TRUE or GL_FALSE). When set to
GL_TRUE, a set of closed contours separating the polygon interior and exterior are
returned instead of a tessellation. Exterior contours are oriented CCW with respect to
the normal; interior contours are oriented CW. The GLU_TESS_BEGIN and
GLU_TESS_BEGIN_DATA callbacks use the type GL_LINE_LOOP for each contour.
GLU_TESS_TOLERANCE
Specifies a tolerance for merging features to reduce the size of the output. For example,
two vertices that are very close to each other might be replaced by a single vertex. The
tolerance is multiplied by the largest coordinate magnitude of any input vertex; this
specifies the maximum distance that any feature can move as the result of a single
merge operation. If a single feature takes part in several merge operations, the total
distance moved could be larger.
Feature merging is completely optional; the tolerance is only a hint. The
implementation is free to merge in some cases and not in others, or to never merge
features at all. The initial tolerance is 0.
The current implementation merges vertices only if they are exactly coincident,
regardless of the current tolerance. A vertex is spliced into an edge only if the
implementation is unable to distinguish which side of the edge the vertex lies on. Two
edges are merged only when both endpoints are identical.
See Also
gluGetTessProperty
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Chapter 18