geometry.h File Reference

Detailed Description

Design Philosophy

These utility functions are can be used for geometric math.

Much of this file was adapted from https://www.jeffreythompson.org/collision-detection/

Usage

No initialization or deinitialization is required. Each function will not modify the given shapes. See the functions below for what is provided and how to use them.

Example

circle_t circ = {
    .pos.x  = 2,
    .pos.y  = 5,
    .radius = 8,
};
rectangle_t rect = {
    .pos.x  = -2,
    .pos.y  = -4,
    .width  = 6,
    .height = 9,
};
if (circleRectIntersection(circ, rect, NULL))
{
    printf("Shapes intersect\n");
}
else
{
    printf("Shapes do not intersect\n");
}

Go to the source code of this file.

Data Structures
struct	circle_t
	Signed integer representation of a circle. More...
struct	rectangle_t
	Signed integer representation of a rectangle. More...
struct	line_t
	Signed integer representation of a line segment. More...
struct	arrow_t

Functions
bool	circleCircleIntersection (circle_t circle1, circle_t circle2, vec_t *collisionVec)
	Check if two circles intersect.
bool	circlePointIntersection (circle_t circle, vec_t point, vec_t *collisionVec)
	Check if a point and a circle intersect.
bool	circleRectIntersection (circle_t circle, rectangle_t rect, vec_t *collisionVec)
	Check if a circle and a rectangle intersect.
bool	circleLineIntersection (circle_t circle, line_t line, vec_t *collisionVec)
	Check if a circle and a line intersect.
bool	rectRectIntersection (rectangle_t rect1, rectangle_t rect2, vec_t *collisionVec)
	Check if two rectangles intersect.
bool	rectLineIntersection (rectangle_t rect, line_t line, vec_t *collisionVec)
	Check if a line intersects with a rectangle.
bool	lineLineIntersection (line_t line1, line_t line2)
	Check if two lines intersect.
arrow_t	initArrow (vec_t base, vec_t tip, int32_t wingLen)
	Initialize an arrow pointing from base to tip.

---

Data Structure Documentation

circle_t

struct circle_t

Data Fields
vec_t	pos	The position of the center of the circle.
int32_t	radius	The radius of the circle.

rectangle_t

struct rectangle_t

Data Fields
vec_t	pos	The position the top left corner of the rectangle.
int32_t	width	The width of the rectangle.
int32_t	height	The height of the rectangle.

line_t

struct line_t

Data Fields
vec_t	p1	One end point of the line segment.
vec_t	p2	The other end point of the line segment.

arrow_t

struct arrow_t

Data Fields
vec_t	base	The base of the arrow.
vec_t	tip	The tip of the arrow.
vec_t	wing1	The base of one of the arrowhead wings.
vec_t	wing2	The base of one of the other arrowhead wing.

Function Documentation

circleCircleIntersection()

bool circleCircleIntersection	(	circle_t	circle1,
		circle_t	circle2,
		vec_t *	collisionVec )

Check if two circles intersect.

Parameters

circle1	[IN] One circle to check for intersection
circle2	[IN] The other circle to check for intersection
collisionVec	[OUT] A vector pointing from the second circle to the first in the direction of the collision. May be NULL.

Returns

true if the circles intersect or touch, false if they do not

circlePointIntersection()

bool circlePointIntersection	(	circle_t	circle,
		vec_t	point,
		vec_t *	collisionVec )

Check if a point and a circle intersect.

Parameters

circle	[IN] A circle to check for intersection
point	[IN] A point to check for intersection
collisionVec	[OUT] A vector pointing from the point to the circle in the direction of the collision. May be NULL.

Returns

true if the point intersects or touches the circle, false if it doesn't

circleRectIntersection()

bool circleRectIntersection	(	circle_t	circle,
		rectangle_t	rect,
		vec_t *	collisionVec )

Check if a circle and a rectangle intersect.

Adapted from https://www.jeffreythompson.org/collision-detection/circle-rect.php

Parameters

circle	[IN] The circle to check for intersection
rect	[IN] The rectangle to check for intersection
collisionVec	[OUT] A vector pointing from the rectangle to the circle in the direction of the collision. May be NULL.

Returns

true if the shapes intersect or touch, false if they do not

circleLineIntersection()

bool circleLineIntersection	(	circle_t	circle,
		line_t	line,
		vec_t *	collisionVec )

Check if a circle and a line intersect.

Adapted from https://www.jeffreythompson.org/collision-detection/line-circle.php

Parameters

circle	[IN] A circle to test intersection
line	[IN] A line to test intersection
collisionVec	[OUT] A vector pointing from the line to the circle in the direction of the collision. This may be NULL.

Returns

true if the circle intersects the line, false if it doesn't

rectRectIntersection()

bool rectRectIntersection	(	rectangle_t	rect1,
		rectangle_t	rect2,
		vec_t *	collisionVec )

Check if two rectangles intersect.

Adapted from https://www.jeffreythompson.org/collision-detection/rect-rect.php

Parameters

rect1	[IN] One rectangle to check for intersection
rect2	[IN] The other rectangle to check for intersection
collisionVec	[OUT] A vector pointing from the second rectangle to the first in the direction of the collision. May be NULL.

Returns

true if the rectangles intersect or touch, false if they do not

rectLineIntersection()

bool rectLineIntersection	(	rectangle_t	rect,
		line_t	line,
		vec_t *	collisionVec )

Check if a line intersects with a rectangle.

Adapted from https://www.jeffreythompson.org/collision-detection/line-rect.php

Parameters

rect	[IN] A rectangle to check for intersection
line	[IN] A line to check for intersection
collisionVec	[OUT] A vector pointing from the rectangle to the line in the direction of the collision. May be NULL.

Returns

true if the line intersects the rectangle, false if it doesn't

lineLineIntersection()

bool lineLineIntersection	(	line_t	line1,
		line_t	line2 )

Check if two lines intersect.

Adapted from https://www.jeffreythompson.org/collision-detection/line-line.php

Parameters

line1	[IN] One line to check for intersection
line2	[IN] Another line to check for intersection

Returns

true if the lines intersect, false if they do not

initArrow()

arrow_t initArrow	(	vec_t	base,
		vec_t	tip,
		int32_t	wingLen )

Initialize an arrow pointing from base to tip.

Parameters

base	The point of the base of the arrow
tip	The point of the tip of the arrow
wingLen	The length of the wings of the arrowhead

Returns

The initialized arrow