Agar

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SYNOPSIS

#include <agar/math.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.

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