NAME

M_Polygon — Agar-Math polygon structure

SYNOPSIS

#include <agar/core.h>
#include <agar/gui.h>
#include <agar/math/m.h>

DESCRIPTION

The M_Polygon structure describes a simple polygon. The polygon may be convex or concave. Self-intersections and holes are not allowed.

typedef struct m_polygon {
	M_Vector2 *v;	/* Vertices */
	Uint n;		/* Vertex count */
} M_Polygon;

INITIALIZATION

void
M_PolygonInit(M_Polygon *P);

M_Polygon
M_POLYGON_INITIALIZER(void);

void
M_PolygonFree(M_Polygon *P);

M_Polygon
M_PolygonFromPts(Uint n, const M_Vector2 *v);

M_Polygon
M_PolygonFromPointSet2(const M_PointSet2 *ps);

M_Polygon
M_PolygonFromPointSet2i(const M_PointSet2i *ps);

M_Polygon
M_PolygonFromLines(Uint n, const M_Line2 *L);

M_PointSet2
M_PolygonToPointSet2(const M_Polygon *P);

M_PointSet2i
M_PolygonToPointSet2i(const M_Polygon *P, M_Real w, M_Real h);

M_Polygon
M_PolygonRead(AG_DataSource *ds);

void
M_PolygonWrite(AG_DataSource *ds, const M_Polygon *P);

The M_PolygonInit() function initializes a M_Polygon structure. The M_POLYGON_INITIALIZER() macro may also be used as a static initializer.

The M_PolygonFree() function releases the memory allocated for vertices.

The M_PolygonFromPts() function returns a polygon structure given an array of points. The M_PolygonFromPointSet() variant accepts a M_PointSet2(3) argument. M_PolygonFromLines() returns a polygon from an array of lines L. n is the number of elements in the array.

The M_PolygonToPointSet2() and M_PolygonToPointSet2i() routines convert a M_Polygon to a M_PointSet2 or M_PointSet2i structure.

The M_PolygonRead() and M_PolygonWrite() functions read or write a polygon structure from/to an AG_DataSource(3).

OPERATIONS

int
M_PolygonAddVertex(M_Polygon *P, M_Vector2 v);

int
M_PolygonAddLine(M_Polygon *P, M_Line2 L);

int
M_PolygonDelVertex(M_Polygon *P, int v);

int
M_PolygonCopy(M_Polygon *Pdst, const M_Polygon *Psrc);

void
M_PolygonScale(M_Polygon *P, M_Real xScale, M_Real yScale);

void
M_PolygonOffset(M_Polygon *P, M_Real xOffs, M_Real yOffs);

int
M_PointInPolygon(const M_Polygon *P, M_Vector2 p);

int
M_PolygonIsConvex(const M_Polygon *P);

The M_PolygonAddVertex() function adds a new vertex to a polygon. Returns index of new vertex on success, -1 on failure. The M_PolygonAddLine() variant accepts a M_Line(3) argument instead of a vector.

M_PolygonDelVertex() removes the vertex at given index v.

The M_PolygonCopy() function copies the vertices of a source polygon Psrc to a destination polygon Pdst. The destination structure does not need to be initialized. Any existing vertices in Pdst will be overwritten. The function returns 0 on success or -1 if insufficient memory is available.

M_PolygonScale() multiplies all vertices of a polygon with the given scaling factors xScale, yScale. M_PolygonOffset() translates all vertices against xOffs, yOffs.

The M_PointInPolygon() function returns 1 if the point p lies inside the polygon.

M_PolygonIsConvex() returns 1 if the polygon is convex.

SEE ALSO

AG_DataSource(3), AG_Intro(3), M_Circle(3), M_Geometry(3), M_Plane(3), M_PointSet(3), M_Polygon(3), M_Rectangle(3), M_Sphere(3), M_Triangle(3), M_Vector(3)

HISTORY

The M_Polygon structure first appeared in Agar 1.3.4.