1 files changed, 103 insertions, 0 deletions
diff --git a/builtin/game/voxelarea.lua b/builtin/game/voxelarea.lua
new file mode 100644
index 000000000..93bbf73a8
--- /dev/null
+++ b/builtin/game/voxelarea.lua
@@ -0,0 +1,103 @@
+VoxelArea = {
+	MinEdge = {x=1, y=1, z=1},
+	MaxEdge = {x=0, y=0, z=0},
+	ystride = 0,
+	zstride = 0,
+}
+
+function VoxelArea:new(o)
+	o = o or {}
+	setmetatable(o, self)
+	self.__index = self
+
+	local e = o:getExtent()
+	o.ystride = e.x
+	o.zstride = e.x * e.y
+
+	return o
+end
+
+function VoxelArea:getExtent()
+	return {
+		x = self.MaxEdge.x - self.MinEdge.x + 1,
+		y = self.MaxEdge.y - self.MinEdge.y + 1,
+		z = self.MaxEdge.z - self.MinEdge.z + 1,
+	}
+end
+
+function VoxelArea:getVolume()
+	local e = self:getExtent()
+	return e.x * e.y * e.z
+end
+
+function VoxelArea:index(x, y, z)
+	local i = (z - self.MinEdge.z) * self.zstride +
+			  (y - self.MinEdge.y) * self.ystride +
+			  (x - self.MinEdge.x) + 1
+	return math.floor(i)
+end
+
+function VoxelArea:indexp(p)
+	local i = (p.z - self.MinEdge.z) * self.zstride +
+			  (p.y - self.MinEdge.y) * self.ystride +
+			  (p.x - self.MinEdge.x) + 1
+	return math.floor(i)
+end
+
+function VoxelArea:position(i)
+	local p = {}
+ 
+	i = i - 1
+
+	p.z = math.floor(i / self.zstride) + self.MinEdge.z
+	i = i % self.zstride
+
+	p.y = math.floor(i / self.ystride) + self.MinEdge.y
+	i = i % self.ystride
+
+	p.x = math.floor(i) + self.MinEdge.x
+
+	return p
+end
+
+function VoxelArea:contains(x, y, z)
+	return (x >= self.MinEdge.x) and (x <= self.MaxEdge.x) and
+		   (y >= self.MinEdge.y) and (y <= self.MaxEdge.y) and
+		   (z >= self.MinEdge.z) and (z <= self.MaxEdge.z)
+end
+
+function VoxelArea:containsp(p)
+	return (p.x >= self.MinEdge.x) and (p.x <= self.MaxEdge.x) and
+		   (p.y >= self.MinEdge.y) and (p.y <= self.MaxEdge.y) and
+		   (p.z >= self.MinEdge.z) and (p.z <= self.MaxEdge.z)
+end
+
+function VoxelArea:containsi(i)
+	return (i >= 1) and (i <= self:getVolume())
+end
+
+function VoxelArea:iter(minx, miny, minz, maxx, maxy, maxz)
+	local i = self:index(minx, miny, minz) - 1
+	local last = self:index(maxx, maxy, maxz)
+	local ystride = self.ystride
+	local zstride = self.zstride
+	local yoff = (last+1) % ystride
+	local zoff = (last+1) % zstride
+	local ystridediff = (i - last) % ystride
+	local zstridediff = (i - last) % zstride
+	return function()
+		i = i + 1
+		if i % zstride == zoff then
+			i = i + zstridediff
+		elseif i % ystride == yoff then
+			i = i + ystridediff
+		end
+		if i <= last then
+			return i
+		end
+	end
+end
+
+function VoxelArea:iterp(minp, maxp)
+	return self:iter(minp.x, minp.y, minp.z, maxp.x, maxp.y, maxp.z)
+end