1 files changed, 132 insertions, 0 deletions
diff --git a/builtin/common/voxelarea.lua b/builtin/common/voxelarea.lua
new file mode 100644
index 000000000..64436bf1a
--- /dev/null
+++ b/builtin/common/voxelarea.lua
@@ -0,0 +1,132 @@
+VoxelArea = {
+	MinEdge = vector.new(1, 1, 1),
+	MaxEdge = vector.new(0, 0, 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()
+	local MaxEdge, MinEdge = self.MaxEdge, self.MinEdge
+	return vector.new(
+		MaxEdge.x - MinEdge.x + 1,
+		MaxEdge.y - MinEdge.y + 1,
+		MaxEdge.z - 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 MinEdge = self.MinEdge
+	local i = (z - MinEdge.z) * self.zstride +
+			  (y - MinEdge.y) * self.ystride +
+			  (x - MinEdge.x) + 1
+	return math.floor(i)
+end
+
+function VoxelArea:indexp(p)
+	local MinEdge = self.MinEdge
+	local i = (p.z - MinEdge.z) * self.zstride +
+			  (p.y - MinEdge.y) * self.ystride +
+			  (p.x - MinEdge.x) + 1
+	return math.floor(i)
+end
+
+function VoxelArea:position(i)
+	local p = {}
+	local MinEdge = self.MinEdge
+
+	i = i - 1
+
+	p.z = math.floor(i / self.zstride) + MinEdge.z
+	i = i % self.zstride
+
+	p.y = math.floor(i / self.ystride) + MinEdge.y
+	i = i % self.ystride
+
+	p.x = math.floor(i) + MinEdge.x
+
+	return p
+end
+
+function VoxelArea:contains(x, y, z)
+	local MaxEdge, MinEdge = self.MaxEdge, self.MinEdge
+	return (x >= MinEdge.x) and (x <= MaxEdge.x) and
+		   (y >= MinEdge.y) and (y <= MaxEdge.y) and
+		   (z >= MinEdge.z) and (z <= MaxEdge.z)
+end
+
+function VoxelArea:containsp(p)
+	local MaxEdge, MinEdge = self.MaxEdge, self.MinEdge
+	return (p.x >= MinEdge.x) and (p.x <= MaxEdge.x) and
+		   (p.y >= MinEdge.y) and (p.y <= MaxEdge.y) and
+		   (p.z >= MinEdge.z) and (p.z <= 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 xrange = maxx - minx + 1
+	local nextaction = i + 1 + xrange
+
+	local y = 0
+	local yrange = maxy - miny + 1
+	local yreqstride = self.ystride - xrange
+
+	local z = 0
+	local zrange = maxz - minz + 1
+	local multistride = self.zstride - ((yrange - 1) * self.ystride + xrange)
+
+	return function()
+		-- continue i until it needs to jump
+		i = i + 1
+		if i ~= nextaction then
+			return i
+		end
+
+		-- continue y until maxy is exceeded
+		y = y + 1
+		if y ~= yrange then
+			-- set i to index(minx, miny + y, minz + z) - 1
+			i = i + yreqstride
+			nextaction = i + xrange
+			return i
+		end
+
+		-- continue z until maxz is exceeded
+		z = z + 1
+		if z == zrange then
+			-- cuboid finished, return nil
+			return
+		end
+
+		-- set i to index(minx, miny, minz + z) - 1
+		i = i + multistride
+
+		y = 0
+		nextaction = i + xrange
+		return i
+	end
+end
+
+function VoxelArea:iterp(minp, maxp)
+	return self:iter(minp.x, minp.y, minp.z, maxp.x, maxp.y, maxp.z)
+end