Initial data commit

Task/Bitmap-Bresenhams-line-algorithm/Lua/bitmap-bresenhams-line-algorithm.lua

@@ -0,0 +1,86 @@
+-----------------------------------------------
+-- 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'})