https://github.com/kikito/bresenham.lua
https://github.com/kikito/bresenham.lua
Last synced: about 1 month ago
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- Host: GitHub
- URL: https://github.com/kikito/bresenham.lua
- Owner: kikito
- License: mit
- Created: 2012-05-07T21:45:29.000Z (over 13 years ago)
- Default Branch: master
- Last Pushed: 2012-05-07T22:24:25.000Z (over 13 years ago)
- Last Synced: 2025-04-23T12:59:10.762Z (6 months ago)
- Language: Lua
- Size: 92.8 KB
- Stars: 29
- Watchers: 2
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: MIT-LICENSE.txt
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README
bresenham.lua
=============
A generic Lua lib that implements Bresenham's line algorithm in two modes:
* `bresenham.los(x0,y0,x1,y1, callback)` returns true if there is a Line Of Sight (or LOS) going
from x0,y0 to x1,y1. It will iterate over each point in the line, invoking `callback(x,y)` on each point.
`callback` must return `true` if the point at `x,y` is "traversable" by the line, and false otherwise.
* `bresenham.line(x0,y0,x1,y1, callback)` is similar to `bresenham.los`, except that it returns *two* values.
The first one is a table of the form `{{x1,y1},{x2,y2} ... {xn,yn}}` with the cells traversed by the algorithm.
The second return value is `true` if a path was found or `false` if it wasn't. This function is slower than `los`,
try to use the other one if you need speed.
Example
-------
```
local bresenham = require 'bresenham'
local map = {
{'#','#','#','#','#','#','#','#'},
{'#','A',' ',' ',' ','B',' ','#'},
{'#',' ',' ',' ',' ',' ',' ','#'},
{'#',' ',' ',' ','#','#','#','#'},
{'#',' ',' ',' ',' ',' ',' ','#'},
{'#',' ',' ',' ',' ','G',' ','#'},
{'#',' ',' ',' ',' ',' ',' ','#'},
{'#','#','#','#','#','#','#','#'},
}
local function printMap()
print()
for x=1,8 do
print(table.concat(map[x]))
end
print()
end
print "Initial map:"
printMap()
local A = bresenham.los(2,2,6,6, function(x,y)
if map[x][y] == '#' then return false end
map[x][y] = 'A'
return true
end)
if A then print("Straight line for A was found:") end
printMap()
local B = bresenham.los(2,6,6,6, function(x,y)
if map[x][y] == '#' then
map[x][y] = 'X'
return false
end
map[x][y] = 'B'
return true
end)
if not B then print("Straight line for B was not found:") end
printMap()
```
This is the expected output:
```
Initial Map:
########
#A B #
# #
# ####
# #
# G #
# #
########
Straight line for A was found:
########
#A #
# A #
# A####
# A #
# A #
# #
########
Straight line for B was not found:
########
#A B #
# A B #
# A#X##
# A #
# A #
# #
########
```