triangulation — Delaunay and Voronoi triangulation and interpolation
#define  GWY_TRIANGULATION_NONE 
typedef  GwyTriangulationPointXY 
typedef  GwyTriangulationPointXYZ 
GwyTriangulationData  
struct  GwyTriangulation 
struct  GwyTriangulationClass 
GObject ╰── GwyTriangulation
#include <libprocess/gwyprocess.h>
GwyTriangulation *
gwy_triangulation_new (void
);
Creates a new triangulation.
A new empty triangulation.
Since: 2.18
gboolean gwy_triangulation_triangulate (GwyTriangulation *triangulation
,guint npoints
,gconstpointer points
,gsize point_size
);
Finds Delaunay and Voronoi triangulations for a set of points in plane.
The triangulation might not work in numerically unstable cases. At present this includes various ambiguous cases with neighbour points on straight lines or circles. Also, no points in the input set may coincide.
It is possible to call this method successively on several different sets
of points to triangulate each separately. Note that pointers in data
returned by methods such as gwy_triangulation_delaunay()
become invalid
then.
triangulation 
Triangulation. 

npoints 
Number of points. 

points 
Array of points. They must be typecastable to
GwyXY for triangulation and to
GwyXYZ for interpolation. However, they can be
larger than that. The actual struct size is indicated by


point_size 
Size of point struct, in bytes. 
TRUE
on success, FALSE
on failure. On failure the triangulation
is empty.
Since: 2.18
gboolean gwy_triangulation_triangulate_iterative (GwyTriangulation *triangulation
,guint npoints
,gconstpointer points
,gsize point_size
,GwySetFractionFunc set_fraction
,GwySetMessageFunc set_message
);
Finds Delaunay and Voronoi triangulations for a set of points in plane.
See gwy_triangulation_triangulate()
for discussion. This function differs
only by the optional set_fraction
and set_message
arguments that permit
providing user feedback for large triangulations and cancelling the
procedure upon request.
triangulation 
Triangulation. 

npoints 
Number of points. 

points 
Array of points. They must be typecastable to GwyXY for
triangulation and to GwyXYZ for interpolation. However, they can
be larger than that. The actual struct size is indicated by


point_size 
Size of point struct, in bytes. 

set_fraction 
Function that sets fraction to output (or 

set_message 
Function that sets message to output (or 
TRUE
on success, FALSE
on failure. On failure the triangulation
is empty. Cancellation via set_fraction
or set_message
callback also counts as failure.
Since: 2.44
gboolean gwy_triangulation_interpolate (GwyTriangulation *triangulation
,GwyInterpolationType interpolation
,GwyDataField *dfield
);
Regularizes XYZ data to a grid, represented by a data field.
The area and resolution of the regular grid is given by the dimensions and
offsets of dfield
.
triangulation 
Triangulation. 

interpolation 
Interpolation to use. Only 

dfield 
Data field to fill with interpolated values. 
TRUE
if the interpolation succeeds, FALSE
on failure, e.g. due to
numerical errors. In the latter case the contents of dfield
is
undefined.
Since: 2.18
void
gwy_triangulation_data_free (GwyTriangulationData *triangulation_data
);
Frees raw triangulation data.
This function should be used to free triangulation data returned by
gwy_triangulation_delaunay()
and similar. It does not free the array
members as they are owned by the triangulation object.
triangulation_data 
Raw triangulation data. 
Since: 2.18
GwyTriangulationData *
gwy_triangulation_delaunay (GwyTriangulation *triangulation
);
Obtains the Delaunay triangulation data.
Notes to the fields in the returned struct:
npoints
equals to the number of points passed to
gwy_triangulation_triangulate()
.
triangulation 
Triangulation. 
Newly clreated GwyTriangulationData that must be freed with
gwy_triangulation_data_free()
when no longer used. The data within
is owned by triangulation
, see GwyTriangulationData.
Since: 2.18
GwyTriangulationData *
gwy_triangulation_boundary (GwyTriangulation *triangulation
);
Obtains the boundary, i.e. convex hull, of Delaunay triangulation.
Notes to the fields in the returned struct:
npoints
equals to the number of points passed to
gwy_triangulation_triangulate()
.
size
is the boundary length.
index
[] contains point indices in the boundary for points on the boundary;
and GWY_TRIANGULATION_NONE
for points not on the boundary.
neighbours
[] lists sequentially the boundary points.
triangulation 
Triangulation. 
Newly clreated GwyTriangulationData that must be freed with
gwy_triangulation_data_free()
when no longer used. The data within
is owned by triangulation
, see GwyTriangulationData.
Since: 2.18
GwyTriangulationData * gwy_triangulation_voronoi (GwyTriangulation *triangulation
,guint *nvpoints
,const GwyXY **vpoints
);
Obtains the Voronoi triangulation data.
Notes to the fields in the returned struct:
npoints
equals to the number of Delaunay triangulation points passed to
gwy_triangulation_triangulate()
plus the number of points in the Voronoi
triangulation, nvpoints
. Voronoi triangulation points are the vertices of
Voronoi cells. So each triangle has one original (Delaunay) point and two
cell vertices (Voronoi points).
index
[] is the usual index of blocks in neighbours
, however,
point indices smaller than the number of Delaunay points correspond to the
Delaunay points, point indices equal or larger correspond to points in
vpoints
(it is necessary to subtract the number of original points to
obtain the real position in vpoints
).
neighbours
[] contains the neighbour blocks, with above caveats about
point numbering.
triangulation 
Triangulation. 

nvpoints 
Location to store the number of new Voronoi triangulation points,
or 

vpoints 
Location to store pointer to the Voronoi triangulation points,
or 
Newly clreated GwyTriangulationData that must be freed with
gwy_triangulation_data_free()
when no longer used. The data within
is owned by triangulation
, see GwyTriangulationData.
Since: 2.18
#define GWY_TRIANGULATION_NONE G_MAXUINT
Point index value representing no point.
Since: 2.18
typedef GwyXY GwyTriangulationPointXY;
typedef GwyXYZ GwyTriangulationPointXYZ;
Representation of a point in plane with associated value for interpolation.
Note this is an alias for GwyXYZ since 2.45.
Since: 2.18
typedef struct { guint npoints; guint size; const guint *index; const guint *neighbours; } GwyTriangulationData;
Representation of raw triangulation data.
Members index
and neighbours
are owned by the GwyTriangulation object
that provided this data and remain valid only until this object is destroyed
or used to perform another triangulation.
The exact interpretation of individual parts depends on what kind of triangulation data it is and may differ a bit from the general description provided here. See the descriptions of individual methods returning GwyTriangulationData.
guint 
Number of points in the set, also detrmines the size of 

guint 
The length of 

const guint * 
Array of size 

const guint * 
Neighbours of each point, represented as indices into some array (which array, that depends on what kind of data it is). The points in each block are sorted counterclockwise. 
Since: 2.18
struct GwyTriangulation;
struct GwyTriangulationClass { GObjectClass parent_class; };