NAME

M_Circle — Agar-Math circle structure

SYNOPSIS

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

DESCRIPTION

The M_Circle2 structure describes a circle in R^2 in terms of an origin point p and radius r:

typedef struct m_circle2 {
	M_Vector2 p;
	M_Real r;
} M_Circle2;

Similarly, M_Circle3 describes a circle in R^3:

typedef struct m_circle3 {
	M_Vector3 p;
	M_Real r;
} M_Circle3;

INITIALIZATION

M_Circle2
M_CircleFromPt(M_Vector2 p, M_Real r);

M_Circle2
M_CircleRead2(AG_DataSource *ds);

M_Circle3
M_CircleRead3(AG_DataSource *ds);

void
M_CircleWrite2(AG_DataSource *ds, M_Circle2 *C);

void
M_CircleWrite3(AG_DataSource *ds, M_Circle3 *C);

M_Circle2
M_CIRCLE2_INITIALIZER(M_Real x, M_Real y, M_Real r);

M_Circle3
M_CIRCLE3_INITIALIZER(M_Real x, M_Real y, M_Real z, M_Real r);

The M_CircleFromPt() function returns a M_Circle2 describing a circle of radius r centered at point p.

The M_CircleRead[23]() and M_CircleWrite[23]() functions read or write a circle structure from/to an AG_DataSource(3).

The macros M_CIRCLE2_INITIALIZER() and M_CIRCLE3_INITIALIZER() expand to static initializers for M_Circle2 and M_Circle3, respectively.

COMPUTATIONS

M_Real
M_CirclePointDistance2(M_Circle2 C, M_Vector2 p);

M_GeomSet2
M_IntersectCircleCircle2(M_Circle2 C1, M_Circle2 C2);

M_GeomSet2
M_IntersectCircleLine2(M_Circle2 C, M_Line2 L);

The M_CirclePointDistance2() routine computes the minimal distance between a circle C and a point p.

M_IntersectCircleCircle2() computes the intersection of two circles in R^2 and returns an M_GeomSet2(3) describing the intersection. The returned set may be:

• Two points.
• One point (circles are tangent up to machine precision).
• A circle (circles are equivalent).
• The empty set.

The M_IntersectCircleCircle2() function computes the intersection of a circle and a line in R^2. The returned set may be:

• Two points.
• One point (line is tangent up to machine precision).
• The empty set.

SEE ALSO

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

HISTORY

The M_Circle structure first appeared in Agar 1.3.4.