User:Monster Iestyn/Source Code Documentation/m_bbox.h

Online link	GitHub entry
File type	C header file
#include guard	__M_BBOX__

This header file contains prototypes for utility functions to be used with "bounding boxes" (fixed_t arrays with 4 elements).

Includes

• m_fixed.h

Bounding box coordinates

These values correspond with the four elements of a bounding box array; each of these four elements stores an X or Y coordinate of one of the box's edges.

Data type	enum

Value	Name	Description
0	BOXTOP	The Y coordinate of the bounding box's top edge
1	BOXBOTTOM	The Y coordinate of the bounding box's bottom edge
2	BOXLEFT	The X coordinate of the bounding box's left edge
3	BOXRIGHT	The X coordinate of the bounding box's right edge

Example usage:

fixed_t bbox[4];

bbox[BOXTOP] = bbox[BOXRIGHT] = FRACUNIT;
bbox[BOXBOTTOM] = bbox[BOXLEFT] = -FRACUNIT;

/* Result:

2 FU x 2 FU bounding box {FRACUNIT, -FRACUNIT, -FRACUNIT, FRACUNIT}
	     BOXTOP
	-----------------
	|       |       |
	|       |       |
	|       |       |
	|       |       |
BOXLEFT	--------0-------- BOXRIGHT
	|       |       |
	|       |       |
	|       |       |
	|       |       |
	-----------------
	    BOXBOTTOM
*/

Function prototypes

Function name	Return type	Params	Defined in	Description
M_ClearBox	void	fixed_t *box	m_bbox.c	"Clears" the bounding box (top and right are set to INT32_MIN, bottom and left are set to INT32_MAX).
M_AddToBox	void	fixed_t *box, fixed_t x, fixed_t y	m_bbox.c	Adds to the bounding box – if (x,y) is a point outside the bounding box, extend the nearest vertical and/or horizontal edges to this point. If the point is completely inside the box, no changes will be made.
M_PointInBox	boolean	fixed_t *box, fixed_t x, fixed_t y	m_bbox.c	Returns true if point (x,y) is inside the bounding box; returns false otherwise.
M_CircleTouchBox	boolean	fixed_t *box, fixed_t circlex, fixed_t circley, fixed_t circleradius	m_bbox.c	Returns true if the bounding box is touching or within a circle with given radius (circleradius) and a center point at (circlex,circley); returns false otherwise. Note: this function does not account for the bounding box being diagonal to the circle, so the "circle" in practice will act more like a box itself.