Add land valuation

.luacheckrc

@@ -4,6 +4,7 @@ allow_defined_top = true
 exclude_files = {
     "mods/mtg",
     "mods/libs/lib_chatcmdbuilder",
+    "mods/libs/lib_utils/vector.lua",
     "mods/mechanics",
     "mods/areas",
     "mods/craftguide",
@@ -13,7 +14,8 @@ globals = {
     "minetest", "company",
     "areas", "sfinv",
     "shop",
-    ChatCmdBuilder = {fields = {"types"}}
+    ChatCmdBuilder = {fields = {"types"}},
+    vector = { fields = {"sqdist"}},
 }
 
 read_globals = {

mods/capitalism/land/api.lua

@@ -136,6 +136,26 @@ function land.get_by_area_id(id)
 end
 
 
+--- Get zone for a plot
+--
+-- Gets the base zone for a particular area
+function land.get_zone(area)
+	assert(type(area) == "table")
+
+	local zone = area
+	while zone do
+		local next = areas.areas[zone.parent]
+		if next and next.land_type ~= area.land_type then
+			return zone
+		end
+
+		zone = next
+	end
+
+	return nil
+end
+
+
 --- Transfers a plot between two owners, after checking relevant permissions.
 --
 -- @int id
@@ -259,6 +279,33 @@ function land.set_price(area, pname, price)
 end
 
 
+--- Calculates a recommended value for the lot, based on the position and more.
+--
+-- @tparam table area
+-- @treturn number value
+function land.calc_value(area)
+	assert(type(area) == "table")
+
+	-- Calculate a weighted metric based on volume of area
+	local pos1, pos2 = vector.sort(area.pos1, area.pos2)
+	local size = vector.subtract(pos2, pos1)
+	local value = 200 * (size.x * size.z * 0.33 * size.y)
+
+	-- Find distance to zone center
+	local zone = land.get_zone(area)
+	if zone then
+		local zone_center = zone.spawn_point or zone.pos1
+		local area_center = vector.divide(vector.add(area.pos1, area.pos2), 2)
+		local dist = vector.sqdist(zone_center, area_center)
+
+		value = value + (zone.land_value or 1000000) * 1 / (dist*0.1 + 2)
+	end
+
+	area.land_value = value
+	return value
+end
+
+
 --- Whether a user can buy a plot
 --
 -- @tparam table area

mods/capitalism/land/tests/api_spec.lua

@@ -7,6 +7,9 @@ _G.audit = function()
 	return { post = function() end }
 end
 
+_G.vector = {}
+
+require("libs/lib_utils/vector")
 require("capitalism/land/api")
 
 _G.company = {}
@@ -153,4 +156,21 @@ describe("land", function()
 		assert.is_true(suc)
 		assert.equals(area.land_sale, 100)
 	end)
+
+	it("calc_value", function()
+		local function v(x, y, z)
+			return { x=x, y=y, z=z }
+		end
+
+		areas.areas = {
+			{ owner="c:government", id=1, name="Root", pos1=v(0,0,0), pos2=v(100,100,100), parent=nil },
+			{ owner="c:government", id=2, name="City", pos1=v(0,0,0), pos2=v(100,100,100), parent=1 },
+			{ owner="c:government", id=3, name="Commercial", land_type="commercial", pos1=v(10,10,10), pos2=v(50,50,50),
+						parent=2, land_value=1000000 },
+			{ owner="c:test", id=4, name="Mall", land_type="commercial",  pos1=v(10,10,10), pos2=v(30,30,30), parent=3 },
+			{ owner="c:test", id=5, name="Shop", land_type="commercial",  pos1=v(10,10,10), pos2=v(20,13,20), parent=4 },
+		}
+
+		assert.equals(land.calc_value(areas.areas[5]), 200*(10*10*3*0.33) + 1000000 * 1 / (52.25*0.1 + 2))
+	end)
 end)

mods/libs/lib_utils/init.lua

@@ -57,3 +57,10 @@ function lib_utils.make_saveload(tab, storage, itemarraykey, registername, class
 		tab.dirty = false
 	end
 end
+
+function vector.sqdist(a, b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return x*x + y*y + z*z
+end

mods/libs/lib_utils/vector.lua

@@ -0,0 +1,149 @@
+vector = {}
+
+function vector.new(a, b, c)
+	if type(a) == "table" then
+		assert(a.x and a.y and a.z, "Invalid vector passed to vector.new()")
+		return {x=a.x, y=a.y, z=a.z}
+	elseif a then
+		assert(b and c, "Invalid arguments for vector.new()")
+		return {x=a, y=b, z=c}
+	end
+	return {x=0, y=0, z=0}
+end
+
+function vector.equals(a, b)
+	return a.x == b.x and
+	       a.y == b.y and
+	       a.z == b.z
+end
+
+function vector.length(v)
+	return math.hypot(v.x, math.hypot(v.y, v.z))
+end
+
+function vector.normalize(v)
+	local len = vector.length(v)
+	if len == 0 then
+		return {x=0, y=0, z=0}
+	else
+		return vector.divide(v, len)
+	end
+end
+
+function vector.floor(v)
+	return {
+		x = math.floor(v.x),
+		y = math.floor(v.y),
+		z = math.floor(v.z)
+	}
+end
+
+function vector.round(v)
+	return {
+		x = math.floor(v.x + 0.5),
+		y = math.floor(v.y + 0.5),
+		z = math.floor(v.z + 0.5)
+	}
+end
+
+function vector.apply(v, func)
+	return {
+		x = func(v.x),
+		y = func(v.y),
+		z = func(v.z)
+	}
+end
+
+function vector.distance(a, b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return math.hypot(x, math.hypot(y, z))
+end
+
+function vector.direction(pos1, pos2)
+	return vector.normalize({
+		x = pos2.x - pos1.x,
+		y = pos2.y - pos1.y,
+		z = pos2.z - pos1.z
+	})
+end
+
+function vector.angle(a, b)
+	local dotp = vector.dot(a, b)
+	local cp = vector.cross(a, b)
+	local crossplen = vector.length(cp)
+	return math.atan2(crossplen, dotp)
+end
+
+function vector.dot(a, b)
+	return a.x * b.x + a.y * b.y + a.z * b.z
+end
+
+function vector.cross(a, b)
+	return {
+		x = a.y * b.z - a.z * b.y,
+		y = a.z * b.x - a.x * b.z,
+		z = a.x * b.y - a.y * b.x
+	}
+end
+
+function vector.add(a, b)
+	if type(b) == "table" then
+		return {x = a.x + b.x,
+			y = a.y + b.y,
+			z = a.z + b.z}
+	else
+		return {x = a.x + b,
+			y = a.y + b,
+			z = a.z + b}
+	end
+end
+
+function vector.subtract(a, b)
+	if type(b) == "table" then
+		return {x = a.x - b.x,
+			y = a.y - b.y,
+			z = a.z - b.z}
+	else
+		return {x = a.x - b,
+			y = a.y - b,
+			z = a.z - b}
+	end
+end
+
+function vector.multiply(a, b)
+	if type(b) == "table" then
+		return {x = a.x * b.x,
+			y = a.y * b.y,
+			z = a.z * b.z}
+	else
+		return {x = a.x * b,
+			y = a.y * b,
+			z = a.z * b}
+	end
+end
+
+function vector.divide(a, b)
+	if type(b) == "table" then
+		return {x = a.x / b.x,
+			y = a.y / b.y,
+			z = a.z / b.z}
+	else
+		return {x = a.x / b,
+			y = a.y / b,
+			z = a.z / b}
+	end
+end
+
+function vector.sort(a, b)
+	return {x = math.min(a.x, b.x), y = math.min(a.y, b.y), z = math.min(a.z, b.z)},
+		{x = math.max(a.x, b.x), y = math.max(a.y, b.y), z = math.max(a.z, b.z)}
+end
+
+function vector.sqdist(a, b)
+	local x = a.x - b.x
+	local y = a.y - b.y
+	local z = a.z - b.z
+	return x*x + y*y + z*z
+end