Below is the full text to include/vision.h from NetHack 3.4.3. To link to a particular line, write [[vision.h#line123]], for example.
/* SCCS Id: @(#)vision.h 3.4 1995/01/26 */
/* Copyright (c) Dean Luick, with acknowledgements to Dave Cohrs, 1990. */
/* NetHack may be freely redistributed. See license for details. */
The NetHack General Public License applies to screenshots, source code and other content from NetHack.
This content was modified from the original NetHack source code distribution (by splitting up NetHack content between wiki pages, and possibly further editing). See thefor a list of who changed it, and on what dates.
#if 0 /* (moved to decl.h) */
extern boolean vision_full_recalc; /* TRUE if need vision recalc */
extern char **viz_array; /* could see/in sight row pointers */
extern char *viz_rmin; /* min could see indices */
extern char *viz_rmax; /* max could see indices */
#define COULD_SEE 0x1 /* location could be seen, if it were lit */
#define IN_SIGHT 0x2 /* location can be seen */
#define TEMP_LIT 0x4 /* location is temporarily lit */
* Light source sources
#define LS_OBJECT 0
#define LS_MONSTER 1
* cansee() - Returns true if the hero can see the location.
* couldsee() - Returns true if the hero has a clear line of sight to
* the location.
#define cansee(x,y) (viz_array[y][x] & IN_SIGHT)
#define couldsee(x,y) (viz_array[y][x] & COULD_SEE)
#define templit(x,y) (viz_array[y][x] & TEMP_LIT)
* The following assume the monster is not blind.
* m_cansee() - Returns true if the monster can see the given location.
* m_canseeu() - Returns true if the monster could see the hero. Assumes
* that if the hero has a clear line of sight to the monster's
* location and the hero is visible, then monster can see the
#define m_cansee(mtmp,x2,y2) clear_path((mtmp)->mx,(mtmp)->my,(x2),(y2))
#define m_canseeu(m) ((!Invis || perceives((m)->data)) && \
!(Underwater || u.uburied || (m)->mburied) ? \
couldsee((m)->mx,(m)->my) : 0)
* Circle information
#define MAX_RADIUS 15 /* this is in points from the source */
/* Use this macro to get a list of distances of the edges (see vision.c). */
#define circle_ptr(z) (&circle_data[(int)circle_start[z]])
#endif /* VISION_H */