87 lines
2.2 KiB
Lua
87 lines
2.2 KiB
Lua
-----------------------------------------------
|
|
-- Bitmap replacement
|
|
-- (why? current Lua impl lacks a "set" method)
|
|
-----------------------------------------------
|
|
local Bitmap = {
|
|
new = function(self, width, height)
|
|
local instance = setmetatable({ width=width, height=height }, self)
|
|
instance:alloc()
|
|
return instance
|
|
end,
|
|
alloc = function(self)
|
|
self.pixels = {}
|
|
for y = 1, self.height do
|
|
self.pixels[y] = {}
|
|
for x = 1, self.width do
|
|
self.pixels[y][x] = 0x00000000
|
|
end
|
|
end
|
|
end,
|
|
clear = function(self, c)
|
|
for y = 1, self.height do
|
|
for x = 1, self.width do
|
|
self.pixels[y][x] = c or 0x00000000
|
|
end
|
|
end
|
|
end,
|
|
get = function(self, x, y)
|
|
x, y = math.floor(x+1), math.floor(y+1)
|
|
if ((x>=1) and (x<=self.width) and (y>=1) and (y<=self.height)) then
|
|
return self.pixels[y][x]
|
|
else
|
|
return nil
|
|
end
|
|
end,
|
|
set = function(self, x, y, c)
|
|
x, y = math.floor(x+1), math.floor(y+1)
|
|
if ((x>=1) and (x<=self.width) and (y>=1) and (y<=self.height)) then
|
|
self.pixels[y][x] = c or 0x00000000
|
|
end
|
|
end,
|
|
}
|
|
Bitmap.__index = Bitmap
|
|
setmetatable(Bitmap, { __call = function (t, ...) return t:new(...) end })
|
|
|
|
------------------------------
|
|
-- Bresenham's Line Algorithm:
|
|
------------------------------
|
|
Bitmap.line = function(self, x1, y1, x2, y2, c)
|
|
local dx, sx = math.abs(x2-x1), x1<x2 and 1 or -1
|
|
local dy, sy = math.abs(y2-y1), y1<y2 and 1 or -1
|
|
local err = math.floor((dx>dy and dx or -dy)/2)
|
|
while(true) do
|
|
self:set(x1, y1, c or 0xFFFFFFFF)
|
|
if (x1==x2 and y1==y2) then break end
|
|
if (err > -dx) then
|
|
err, x1 = err-dy, x1+sx
|
|
if (x1==x2 and y1==y2) then
|
|
self:set(x1, y1, c or 0xFFFFFFFF)
|
|
break
|
|
end
|
|
end
|
|
if (err < dy) then
|
|
err, y1 = err+dx, y1+sy
|
|
end
|
|
end
|
|
end
|
|
|
|
--------
|
|
-- Demo:
|
|
--------
|
|
Bitmap.render = function(self, charmap)
|
|
for y = 1, self.height do
|
|
local rowtab = {}
|
|
for x = 1, self.width do
|
|
rowtab[x] = charmap[self.pixels[y][x]]
|
|
end
|
|
print(table.concat(rowtab))
|
|
end
|
|
end
|
|
local bitmap = Bitmap(61,21)
|
|
bitmap:clear()
|
|
bitmap:line(0,10,30,0)
|
|
bitmap:line(30,0,60,10)
|
|
bitmap:line(60,10,30,20)
|
|
bitmap:line(30,20,0,10)
|
|
bitmap:render({[0x000000]='.', [0xFFFFFFFF]='X'})
|