Description
SVPs cannot be created in many different ways:
art_svp_from_vpath
and art_vpath_from_svp
can be used to generate SVPs from a Vpath and to generate
VPaths from SVPs.
Once SVPs have been created, it is possible to manipulate them
and apply a number of interesting operations on them. Most notably,
it is possible to do the union of two SVPs with
art_svp_union (Given two SVPs,
the union of these two SVPs is an SVP representing the area obtained by
the concatenation of the underlying areas of the two original SVPs).
art_svp_intersect calculates the
intersection of two SVPs: the resulting SVPs contain points which were
in the two original SVPs.
Finally, art_svp_diff calculates the
difference of two SVPs: the resulting SVPs contains all the points which
were in only one of the original SVP.
These operations are sumamrized below:
Details
art_vpath_from_svp ()
ArtVpath* art_vpath_from_svp (const ArtSVP *svp); |
Converts the sorted vector path svp into standard vpath form.
art_svp_from_vpath ()
ArtSVP* art_svp_from_vpath (ArtVpath *vpath); |
Converts a vector path into sorted vector path form. The svp form is
more efficient for rendering and other vector operations.
Basically, the implementation is to traverse the vector path,
generating a new segment for each "run" of points in the vector
path with monotonically increasing Y values. All the resulting
values are then sorted.
Note: I'm not sure that the sorting rule is correct with respect
to numerical stability issues.
art_svp_union ()
ArtSVP* art_svp_union (const ArtSVP *svp1,
const ArtSVP *svp2); |
Computes the union of the two argument svp's. Given two svp's with
winding numbers of 0 and 1 everywhere, the resulting winding number
will be 1 where either (or both) of the argument svp's has a
winding number 1, 0 otherwise. The result is newly allocated.
Currently, this routine has accuracy problems pending the
implementation of the new intersector.
art_svp_intersect ()
ArtSVP* art_svp_intersect (const ArtSVP *svp1,
const ArtSVP *svp2); |
Computes the intersection of the two argument svp's. Given two
svp's with winding numbers of 0 and 1 everywhere, the resulting
winding number will be 1 where both of the argument svp's has a
winding number 1, 0 otherwise. The result is newly allocated.
Currently, this routine has accuracy problems pending the
implementation of the new intersector.
art_svp_diff ()
ArtSVP* art_svp_diff (const ArtSVP *svp1,
const ArtSVP *svp2); |
Computes the symmetric of the two argument svp's. Given two svp's
with winding numbers of 0 and 1 everywhere, the resulting winding
number will be 1 where either, but not both, of the argument svp's
has a winding number 1, 0 otherwise. The result is newly allocated.
Currently, this routine has accuracy problems pending the
implementation of the new intersector.
