Discussion:Field of Vision

Half-width walls, center to center

Suggested by Eddie(PowerDiver).

This is a symmetrical system.

Consequences:

################D
@

Fig 1. @ can see D, D can see @

##D
##
@

Fig 2. Indeterminate (probably resolve to not visible).

#m
#
@#

Fig 3. Vital that @ can see m in this case.

......................
.@#                 M
......................

Fig 4. @ cannot see M (by zero-width blockage sub-rule - see fig 2)

.......
.@.....
...#...
..... .
.......

Fig 5. Discontinuous gaps in viewable area (by zero-width blockage)

Monsters occupy half the width/height of grid

Suggested by jv123.

Monsters, characters, items are in the center of their grid's square taking up half the width/height. If lines from any point in the @'s sub-square can go to any point in the M's sub-square without crossing a wall then each is visible by the other. Walls take up the full grid square.

This is a symmetrical system.

Consequences.

#####D######
@

Fig 6. @ cannot see D.

####D#######
@

Fig 7. It is indeterminate whether @ can see D or not (zero-width cross).

###D########
@

Fig 8. @ can see D and D can see @

Center to Center, subdivided grid

Suggested by Marble Dice

Any tile that can have a line drawn from the center of the @ to the center of the tile is without crossing an obstructed point is visible. Each wall takes up the middle 2x2 of the 4x4 sub-divided grid.

For visibility purposes a monster on a wall-tile is not treated differently from a monster on a floor tile.

Consequences.

#######.#######
#######@#######
????.......????
?.............?

Fig 8. From the entrance of a room.

................?
.........????????
.@.###?????M?????
.........????????
................?

Fig 9. @ cannot see M.

@...........
...#?.......
.....????...
.......?????
.........???

Fig 10. Expanding shadow triangle from pillar.

####D
@....

Fig 11. @ cannot see D.

###D#
@....

Fig 12. @ can just see D? (indeterminate case - depends on zero-width cross decision)

##D##
@....

Fig 13. @ can see D.

Digital FOV

First mentioned by Atanvarno

See Digital field of view for details. Digital FOV is a symmetrical system.

Consequences.

  %%%%#%%
  %  .   
 %% ###%%
 % ...#
##....#
@.....#%%%%
##........#%
 % ...###...
 %  ..# %%%%
 %%%%##

Fig 14. Digital FOV ex.  %'s are walls out of sight.

Traditional (Angband)

First mentioned by Atanvarno

Trick shots are possible (e.g. you can shoot at indirectly targeted grids that you cannot see or target directly).

Consequences.

###X.B
A.....

Fig 15. A cannot see X but can hit it by shooting at B.

Intentionally unsymmetrical

Suggested by will_asher

Monsters caught in open hallway have no where to hide. Intelligent @'s can peek round corners without being spotted.

    #.#    
#####@#
..M...#
#######

Fig 16. @ can see M, but M can't see @.

Wouldn't it be nice if ...

Suggested by PaulBlay

Wouldn't it be nice if ...

• What you see is what you can hit with a spell (and vice versa).
• What you see can also see you (and vice versa).
• Standing directly next to a pillar should produce an expanding shadow.
• Reasonably fast code can be produced to implement the FOV, etc.
• No 'trick shots' required (or possible) to hit monsters that you can't target directly.

Is everyone agreed on the above (if they are possible)?

How does the current system specifically differ from the above?

Are any of those points not possible?

PowerDiver is of the opinion that it is not possible to have all five of those at the same time.

Other points for consideration

Should @'s and M's have an infinite field of view?

#################################################################################################
.@.............................................................................................M.
#################################################################################################

Fig 17. Should @ see M ?

Special cases for walls (etc.)

• Case 1 half-width walls. and Case 2 Digital FOV.

################################################################################################
.@..............................................................................................

Fig 18. @ can see the wall, and monsters in the wall, for as far as it goes.

• Case 2 and Case 3

####?%%%%%%
.@.........

Fig 19. @ can see #, % are walls he can't see, ? is indeterminate

The question is whether walls (but not monsters in walls) should be filled in when they are not visible, but are adjacent to room / corridor tiles that are visible and lit.

#####G#####
.@.........

Fig 20. @ can't see G (but can see wall G is in).

See also

Field of Vision