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.