Discussion:Field of Vision
Half-width walls, center to center
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
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
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.