bbox2(3G)bbox2(3G)NAME
bbox2, bbox2i, bbox2s - culls and prunes to bounding box and minimum
pixel radius
C SPECIFICATION
void bbox2(xmin, ymin, x1, y1, x2, y2)
Screencoord xmin, ymin;
Coord x1, y1, x2, y2;
void bbox2i(xmin, ymin, x1, y1, x2, y2)
Screencoord xmin, ymin;
Icoord x1, y1, x2, y2;
void bbox2s(xmin, ymin, x1, y1, x2, y2)
Screencoord xmin, ymin;
Scoord x1, y1, x2, y2;
All of the above routines are functionally the same. They differ only in
the declaration types of their parameters.
PARAMETERS
xmin expects the width, in pixels, of the smallest displayable feature.
ymin expects the height, in pixels, of the smallest displayable
feature.
x1 expects the x coordinate of a corner of the bounding box.
y1 expects the y coordinate of a corner of the bounding box.
x2 expects the x coordinate of a corner of the bounding box. The
corner referenced by this parameter must be diagonally opposite
the corner referenced by the x1 and y1 parameters.
y2 expects the y coordinate of a corner of the bounding box. The
corner referenced by this parameter must be diagonally opposite
the corner referenced by the x1 and y1 parameters.
DESCRIPTION
bbox2 performs the graphical functions known as culling and pruning.
Culling prevents the system from drawing objects that are less than the
minimum feature size (xmin and ymin). Pruning prevents the system from
drawing objects that lie completely outside the viewport.
To determine whether or not to cull an object, bbox2 tests whether or not
the display of a rectangle the size of the bounding box is smaller than
the minimum feature size. To determine whether or not to prune an object,
bbox2 tests whether or not the bounding box is completely outside the
viewport.
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bbox2(3G)bbox2(3G)
Call bbox2 within the definition for an object, just after the call to
makeobj. If the object must be pruned or culled, the remainder of the
object definition is ignored.
SEE ALSO
makeobj
NOTES
This routine does not function in immediate mode.
This routine is not a free test. If you use bbox2 too freely, your
performance can suffer. Reserve bbox2 for complicated object definitions
only.
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