point.h File Reference

#include <stdbool.h>

Go to the source code of this file.

Classes
struct	Point
struct	Point_List

Typedefs
typedef struct Point	bl_point
typedef struct Point_List	bl_point_list

Functions
bl_point_list *	bl_make_point_list ()
void	bl_add_point_xy (bl_point_list *list, double x, double y)
void	bl_add_point (bl_point_list *list, bl_point *p)
int	bl_point_list_count (bl_point_list *list)
void	bl_point_list_destroy (bl_point_list *list)
bl_point *	bl_make_point (double x, double y)
bl_point *	bl_lerp_point (double t, bl_point *p0, bl_point *p1)
bl_point *	bl_random_point (double x, double y, double w, double h)
bl_point *	bl_random_point_in_circle (double x, double y, double r)
bl_point *	bl_random_point_in_triangle (bl_point *p0, bl_point *p1, bl_point *p2)
bl_point *	bl_point_from_polar (double angle, double radius)
double	bl_point_distance (bl_point *p0, bl_point *p1)
double	bl_point_magnitude (bl_point *p)
double	bl_point_angle (bl_point *p)
void	bl_point_translate (bl_point *p, double x, double y)
void	bl_point_scale (bl_point *p, double sx, double sy)
void	bl_point_rotate (bl_point *p, double angle)
double	bl_dot_product (bl_point *p0, bl_point *p1, bl_point *p2, bl_point *p3)
double	bl_angle_between (bl_point *p0, bl_point *p1, bl_point *p2, bl_point *p3)
bl_point *	bl_bezier_point (bl_point *p0, bl_point *p1, bl_point *p2, bl_point *p3, double t)
bl_point *	bl_quadratic_point (bl_point *p0, bl_point *p1, bl_point *p2, double t)
bl_point *	bl_segment_intersect (bl_point *p0, bl_point *p1, bl_point *p2, bl_point *p3)
bl_point *	bl_tangent_point_to_circle (bl_point *p, double x, double y, double r, bool anticlockwise)

Typedef Documentation

bl_point

typedef struct Point bl_point

A struct for holding a single point in a linked list.

bl_point_list

typedef struct Point_List bl_point_list

A struct holding the head and tail of a linked list.

Function Documentation

bl_add_point()

void bl_add_point	(	bl_point_list *	list,
		bl_point *	p
	)

Adds a point to a point list.

Parameters

bl_point_list	*list The list to add to.
bl_point	*point The point to add.

Examples

bl_point *p = bl_make_point(100, 100);
bl_add_point(path, p);

bl_add_point_xy()

void bl_add_point_xy	(	bl_point_list *	list,
		double	x,
		double	y
	)

Adds an x, y point to a point list.

Parameters

bl_point_list	*list The list to add to.
double	x The x value of the point to add.
double	y The y value of the point to add.

Examples

bl_add_point_xy(path, 100, 100);

bl_angle_between()

double bl_angle_between	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2,
		bl_point *	p3
	)

Returns the angle between two lines defined by four points.

Parameters

bl_point	*p0 The first point of the first line.
bl_point	*p1 The second point of the first line.
bl_point	*p2 The first point of the second line.
bl_point	*p4 The second point of the second line.

Returns

double

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(100, 100);
bl_point *p3 = bl_make_point(140, 300);
double angle = bl_angle_between(p0, p1, p2, p3);

bl_bezier_point()

bl_point* bl_bezier_point	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2,
		bl_point *	p3,
		double	t
	)

Returns a point on a Bezier curve.

The t parameter is in the range of 0 to 1. 0 will return the first point. 1 will return the final point. A value between 0 and 1 will return a point along the Bezier path formed by the four points.

Parameters

bl_point	*p0 The first point.
bl_point	*p1 The second point.
bl_point	*p2 The third point.
bl_point	*p3 The fourth point.
double	t The interpolation value.

Returns

bl_point*

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(300, 100);
bl_point *p3 = bl_make_point(400, 300);
bl_point *p4 = bl_bezier_point(p0, p1, p2, p3, 0.2);

bl_dot_product()

double bl_dot_product	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2,
		bl_point *	p3
	)

Returns the dot product of two angles formed by four points.

Parameters

bl_point	*p0 The first point of the first line.
bl_point	*p1 The second point of the first line.
bl_point	*p2 The first point of the second line.
bl_point	*p4 The second point of the second line.

Returns

double

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(100, 100);
bl_point *p3 = bl_make_point(140, 300);
double dp = bl_dot_product(p0, p1, p2, p3);

bl_lerp_point()

bl_point* bl_lerp_point	(	double	t,
		bl_point *	p0,
		bl_point *	p1
	)

Returns a new point interpolated between two other points.

Parameters

double	t The interpolation value. Usually 0 to 1.
bl_point	*p0 The first point.
bl_point	*p1 The second point.

Returns

bl_point*

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 500);
bl_point *p2 = bl_lerp_point(0.35, p0, p1);

bl_make_point()

bl_point* bl_make_point	(	double	x,
		double	y
	)

Creates a new point.

Parameters

double	x The x value of the point.
double	y The y value of the point.

Returns

bl_point*

Examples

bl_point *p = bl_make_point(100, 100);

bl_make_point_list()

bl_point_list* bl_make_point_list

(

)

Creates a linked list of point objects.

Returns

bl_point_list*

Examples

bl_point_list *path = bl_make_point_list();

bl_point_angle()

double bl_point_angle

(

bl_point *

p

)

Returns the angle from the origin to a point.

Parameters

bl_point

*p The point.

Returns

double

Examples

bl_point *p = bl_make_point(200, 150);
double angle = bl_point_angle(p);

bl_point_distance()

double bl_point_distance	(	bl_point *	p0,
		bl_point *	p1
	)

Returns the distance between two points.

Parameters

bl_point	*p0 The first point.
bl_point	*p1 The second point.

Returns

double

Examples

bl_point *p0 = bl_make_point(200, 150);
bl_point *p1 = bl_make_point(140, 300);
double dist = bl_point_distance(p0, p1);

bl_point_from_polar()

bl_point* bl_point_from_polar	(	double	angle,
		double	radius
	)

Returns a new point based on an angle and radius.

Parameters

double	angle The angle from the origin.
double	radius The distance from the origin.

Returns

bl_point*

Examples

bl_point *p = bl_point_from_polar(PI / 4, 100);

bl_point_list_count()

int bl_point_list_count

(

bl_point_list *

list

)

Returns the number of points in a point list.

Parameters

bl_point_list

*list The list to get a count for.

Returns

int

Examples

int count = bl_point_list_count(path);

bl_point_list_destroy()

void bl_point_list_destroy

(

bl_point_list *

list

)

Frees the memory for each point in a point list and for the list itself.

Parameters

bl_point_list

*list The list to destroy.

Examples

bl_point_list_destroy(path);

bl_point_magnitude()

double bl_point_magnitude

(

bl_point *

p

)

Returns the magnitude (distance from origin) of a point.

Parameters

bl_point

*p The point.

Returns

double

Examples

bl_point *p = bl_make_point(200, 150);
double mag = bl_point_magnitude(p);

bl_point_rotate()

void bl_point_rotate	(	bl_point *	p,
		double	angle
	)

Rotates a point around the origin.

Parameters

bl_point	*p The point.
double	angle The angle to rotate by.

Examples

bl_point *p = bl_make_point(200, 150);
bl_point_rotate(p, PI / 4);

bl_point_scale()

void bl_point_scale	(	bl_point *	p,
		double	sx,
		double	sy
	)

Scales a point from the origin.

Parameters

bl_point	*p The point.
double	sx How much to scale on the x-axis.
double	sy How much to scale on the y-axis.

Examples

bl_point *p = bl_make_point(200, 150);
bl_point_scale(p, 2, 3);

bl_point_translate()

void bl_point_translate	(	bl_point *	p,
		double	x,
		double	y
	)

Translates a point.

Parameters

bl_point	*p The point.
double	x How much to translate on the x-axis.
double	y How much to translate on the y-axis.

Examples

bl_point *p = bl_make_point(200, 150);
bl_point_translate(p, 100, 50);

bl_quadratic_point()

bl_point* bl_quadratic_point	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2,
		double	t
	)

Returns a point on a quadratic Bezier curve.

The t parameter is in the range of 0 to 1. 0 will return the first point. 1 will return the final point. A value between 0 and 1 will return a point along the quadratic Bezier path formed by the three points.

Parameters

bl_point	*p0 The first point.
bl_point	*p1 The second point.
bl_point	*p2 The third point.
double	t The interpolation value.

Returns

bl_point*

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(300, 100);
bl_point *p4 = bl_quadratic_point(p0, p1, p2, p3, 0.2);

bl_random_point()

bl_point* bl_random_point	(	double	x,
		double	y,
		double	w,
		double	h
	)

Returns a random point withint a defined rectangle.

Parameters

double	x The x position of the rectangle.
double	y The y position of the rectangle.
double	w The width of the rectangle.
double	h The height of the rectangle.

Returns

bl_point*

Examples

bl_point *p = bl_random_point(0, 0, 500, 500);

bl_random_point_in_circle()

bl_point* bl_random_point_in_circle	(	double	x,
		double	y,
		double	r
	)

Returns a random point within a defined circle.

Parameters

double	x The x position of the circle.
double	y The y position of the circle.
double	r The radius of the circle.

Returns

bl_point*

Examples

bl_point *p = bl_random_point_in_circle(100, 100, 50);

bl_random_point_in_triangle()

bl_point* bl_random_point_in_triangle	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2
	)

Returns a random point that will be within a triangle defined by three points.

Parameters

bl_point	*p0 The first point of the triangle.
bl_point	*p1 The second point of the triangle.
bl_point	*p2 The third point of the triangle.

Returns

bl_point*

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(140, 300);
bl_point *p3 = bl_random_point_in_triangle(p0, p1, p2);

bl_segment_intersect()

bl_point* bl_segment_intersect	(	bl_point *	p0,
		bl_point *	p1,
		bl_point *	p2,
		bl_point *	p3
	)

Returns whether or not too line segments intersect.

Parameters

bl_point	*p0 The first point of the first line.
bl_point	*p1 The second point of the first line.
bl_point	*p2 The first point of the second line.
bl_point	*p4 The second point of the second line.

Returns

bool

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *p1 = bl_make_point(200, 150);
bl_point *p2 = bl_make_point(300, 100);
bl_point *p3 = bl_make_point(400, 300);
bool intersect = bl_segment_intersect(p0, p1, p2, p3);

bl_tangent_point_to_circle()

bl_point* bl_tangent_point_to_circle	(	bl_point *	p,
		double	x,
		double	y,
		double	r,
		bool	anticlockwise
	)

Given the specified point and circle, finds another point on the circle that will form a line tangent to the circle.

Parameters

bl_point	*p The initial point.
double	x The x position of the circle.
double	y The y position of the circle.
double	r The radius of the circle.
bool	anticlockwise Which side of the circle to find the tangent point on.

Examples

bl_point *p0 = bl_make_point(100, 100);
bl_point *tangent = bl_tangent_point_to_circle(p, 200, 100, 50, false);