Initial commit

README.md

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+# Xiangqi - Chinese chess for Minetest
+
+## Usage
+
+The board currently does not have a crafting recipe. You currently need
+to get it from the inventory in creative mode.
+
+Right-click a figure to select it (or, if it is already selected,
+deselect it). The selected figure is marked green, and the possible
+target positions are marked, with (in particular) targetable figures
+from the opposing side marked blue. Left-click on the target to move
+the selected figure to the target position.
+
+The figures face the side that should make a move.
+
+Wikipedia has a page on the rules (and pieces) of Xiangqi.
+
+## Limitations/To-do
+
+* The game does not check whether the move results in the king/general
+(帥/將) being captured.
+* The game does not check for check(mate)s.
+* The player is not notified when the game ends.
+* The moves are not recorded.
+* The figures may appear weird in certain circumstances.
+
+## Licenses
+
+* The source code is licensed under GNU AGPLv3.
+* Textures (see below for exceptions) are licensed under CC0.
+* `xiangqi_figures.png` is licensed under SIL OFL.

init.lua

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+local S = minetest.get_translator "xiangqi"
+
+local yoff = -15/32
+local vstep = 16/177
+local figheight = 1/2+yoff
+
+local function objects_in_cube(pos, r)
+	return minetest.get_objects_in_area(vector.offset(pos, -r, -r, -r), vector.offset(pos, r, r, r))
+end
+
+local v2d = {}
+local v2d_mt = {
+	__add = function(a, b)
+		return v2d.new(a.x+b.x, a.y+b.y)
+	end,
+	__sub = function(a, b)
+		return v2d.new(a.x-b.x, a.y-b.y)
+	end,
+	__unm = function(v)
+		return v2d.new(-v.x, -v.y)
+	end,
+	__eq = function(a, b)
+		return a.x == b.x and a.y == b.y
+	end,
+	__index = v2d,
+}
+
+function v2d.new(x, y)
+	return setmetatable({x = x, y = y}, v2d_mt)
+end
+
+function v2d:copy()
+	return v2d.new(self.x, self.y)
+end
+
+function v2d:transpose()
+	return v2d.new(self.y, self.x)
+end
+
+function v2d:to3d(base)
+	local row, col = self.y, self.x
+	local v = vector.new((col-4)*vstep, yoff+figheight/2, (row-4.5)*vstep)
+	if base then
+		return base + v
+	else
+		return v
+	end
+end
+
+function v2d:in_bound()
+	return self.x >= 0 and self.x <= 8 and self.y >= 0 and self.y <= 9
+end
+
+function v2d:assert_bound()
+	if self:in_bound() then
+		return self
+	end
+	return nil
+end
+
+function v2d.raynext(step, pos)
+	return (step+pos):assert_bound()
+end
+
+function v2d.forray(pos, step)
+	return v2d.raynext, step, pos
+end
+
+local game = {}
+local game_mt = {__index = game}
+
+function game.new(pos)
+	return setmetatable({
+		basepos = pos,
+	}, game_mt)
+end
+
+local function spawn_piece(...)
+	local p0, row, col = ...
+	local obj = minetest.add_entity(v2d.new(col, row):to3d(p0), "xiangqi:figure", minetest.serialize{...})
+	return obj
+end
+
+local function spawn_target_marker(p0, row, col)
+	return minetest.add_entity(v2d.new(col, row):to3d(p0), "xiangqi:target_marker", minetest.serialize{p0, row, col})
+end
+
+function game:setup()
+	self:set_done(false)
+	local pos = self.basepos
+	for ptype, rmod in pairs{
+		[false] = function(x) return x end,
+		[true] = function(x) return 9-x end,
+	} do
+		for _, cmod in pairs {
+			function(x) return x end,
+			function(x) return 8-x end,
+		} do
+			for _, t in pairs {
+				{0, 0, "chariot"},
+				{0, 1, "horse"},
+				{0, 2, "elephant"},
+				{0, 3, "advisor"},
+				{2, 1, "cannon"},
+				{3, 0, "pawn"},
+				{3, 2, "pawn"},
+			} do
+				spawn_piece(pos, rmod(t[1]), cmod(t[2]), t[3], ptype)
+			end
+		end
+		for r, fig in pairs {
+			[0] = "king",
+			[3] = "pawn",
+		} do
+			spawn_piece(pos, rmod(r), 4, fig, ptype)
+		end
+	end
+end
+
+function game:teardown()
+	for _, obj in pairs(objects_in_cube(self.basepos, 0.5)) do
+		local ename = obj:get_entity_name()
+		if ename == "xiangqi:figure" or ename == "xiangqi:target_marker" then
+			obj:remove()
+		end
+	end
+end
+
+function game:node_meta()
+	local meta = minetest.get_meta(self.basepos)
+	self.node_meta = function() return meta end
+	return meta
+end
+
+function game:get_done()
+	return minetest.is_yes(self:node_meta():get_int("gameend"))
+end
+
+function game:set_done(st)
+	self:node_meta():set_int("gameend", st and 1 or 0)
+end
+
+function game:get_side()
+	return minetest.is_yes(self:node_meta():get_int("pturn"))
+end
+
+function game:set_side(s)
+	self:node_meta():set_int("pturn", s and 1 or 0)
+end
+
+function game:flip_side()
+	return self:set_side(not self:get_side())
+end
+
+function game:get_selection()
+	local meta = self:node_meta()
+	local row, col = meta:get_int("selrow"), meta:get_int("selcol")
+	return v2d.new(col-1, row-1):assert_bound()
+end
+
+function game:set_selection(pos)
+	local meta = self:node_meta()
+	local row, col = 0, 0
+	if pos then
+		row, col = pos.y+1, pos.x+1
+	end
+	meta:set_int("selrow", row)
+	meta:set_int("selcol", col)
+end
+
+function game:get_figure(pos)
+	if not pos then
+		return nil
+	end
+	for _, obj in pairs(minetest.get_objects_inside_radius(pos:to3d(self.basepos), vstep/2)) do
+		if obj:get_entity_name() == "xiangqi:figure" then
+			return obj:get_luaentity()
+		end
+	end
+	return nil
+end
+
+function game:get_selected_figure()
+	return self:get_figure(self:get_selection())
+end
+
+function game:update_board()
+	for _, obj in pairs(objects_in_cube(self.basepos, 0.5)) do
+		local ename = obj:get_entity_name()
+		if ename == "xiangqi:figure" then
+			local ent = obj:get_luaentity()
+			ent._reachable = false
+			ent:_update_appearance()
+		elseif ename == "xiangqi:target_marker" then
+			obj:remove()
+		end
+	end
+	local selfig = self:get_selected_figure()
+	if selfig then
+		for _, pos in pairs(selfig:_list_reachable()) do
+			local fig = self:get_figure(pos)
+			if fig then
+				if fig._pside ~= selfig._pside then
+					fig._reachable = true
+					fig:_update_appearance()
+				end
+			else
+				spawn_target_marker(self.basepos, pos.y, pos.x)
+			end
+		end
+	end
+end
+
+function game:move(fig, tpos)
+	if not fig then
+		return false
+	end
+	local tfig = self:get_figure(tpos)
+	if tfig then
+		if tfig._ptype == "king" then
+			self:set_done(true)
+		end
+		tfig.object:remove()
+	end
+	fig._row, fig._col, fig._pos = tpos.y, tpos.x, tpos
+	fig.object:set_pos(tpos:to3d(self.basepos))
+	return true
+end
+
+function game:gamemove(tpos)
+	local selfig = self:get_selected_figure()
+	self:set_selection()
+	self:update_board()
+	minetest.after(0, function()
+		if self:move(selfig, tpos) then
+			self:flip_side()
+			self:update_board()
+		end
+	end)
+end
+
+local figstex = "xiangqi_figure_side.png"
+
+minetest.register_entity("xiangqi:target_marker", {
+	visual = "cube",
+	visual_size = {x = vstep, y = figheight},
+	selectionbox = {-vstep/2, -figheight/2, -vstep/2, vstep/2, figheight/2, vstep/2},
+	textures = {figstex, figstex, figstex, figstex, figstex, figstex},
+	on_activate = function(self, staticdata)
+		self._p0, self._row, self._col = unpack(minetest.deserialize(staticdata or {}))
+		self._game = game.new(self._p0)
+		self._pos = v2d.new(self._col, self._row)
+		self.object:set_armor_groups{immortal = 100}
+	end,
+	on_punch = function(self)
+		self._game:gamemove(self._pos)
+	end,
+})
+
+minetest.register_entity("xiangqi:figure", {
+	initial_properties = {
+		visual = "cube",
+		visual_size = {x = vstep, y = figheight},
+		selectionbox = {-vstep/2, -figheight/2, -vstep/2, vstep/2, figheight/2, vstep/2}
+	},
+	on_activate = function(self, staticdata)
+		self._p0, self._row, self._col, self._ptype, self._pside = unpack(minetest.deserialize(staticdata or {}))
+		self.object:set_armor_groups{immortal = 100}
+		self._game = game.new(self._p0)
+		self._pos = v2d.new(self._col, self._row)
+		self:_update_appearance()
+	end,
+	get_staticdata = function(self)
+		return minetest.serialize{self._p0, self._row, self._col, self._ptype, self._pside}
+	end,
+	on_rightclick = function(self, clicker)
+		if self._game:get_side() ~= self._pside then
+			if clicker:is_player() then
+				minetest.chat_send_player(clicker:get_player_name(), S("It is not yet your turn."))
+			end
+			return
+		end
+		if self:_is_selected() then
+			self._game:set_selection()
+		elseif self._game:get_done() then
+			if clicker:is_player() then
+				minetest.chat_send_player(clicker:get_player_name(), S("The game has ended"))
+			end
+		else
+			self._game:set_selection(self._pos)
+		end
+		self._game:update_board()
+	end,
+	on_punch = function(self)
+		if self._reachable then
+			self._game:gamemove(self._pos)
+		end
+	end,
+	_list_reachable = function(self)
+		local game = self._game
+		local t = {}
+		local fourdirs = {v2d.new(0, 1), v2d.new(0, -1), v2d.new(1, 0), v2d.new(-1, 0)}
+		local diagdirs = {v2d.new(1, 1), v2d.new(1, -1), v2d.new(-1, 1), v2d.new(-1, -1)}
+		if self._ptype == "king" then
+			local midrow = self._pside and 8 or 1
+			for _, step in pairs(fourdirs) do
+				local pos = self._pos+step
+				if math.abs(pos.x-4) <= 1 and math.abs(pos.y-midrow) <= 1 then
+					table.insert(t, pos)
+				end
+				for pos in self._pos:forray(step) do
+					local fig = game:get_figure(pos)
+					if fig then
+						if fig._ptype == "king" then
+							table.insert(t, pos)
+						end
+						break
+					end
+				end
+			end
+		elseif self._ptype == "advisor" then
+			local midrow = self._pside and 8 or 1
+			for _, step in pairs(diagdirs) do
+				local pos = self._pos+step
+				if math.abs(pos.x-4) <= 1 and math.abs(pos.y-midrow) <= 1 then
+					table.insert(t, pos)
+				end
+			end
+		elseif self._ptype == "elephant" then
+			for _, step in pairs(diagdirs) do
+				local p1 = self._pos+step
+				if (not game:get_figure(p1)) then
+					local tar = p1+step
+					if (tar.y > 4.5) == self._pside then
+						table.insert(t, tar:assert_bound())
+					end
+				end
+			end
+		elseif self._ptype == "horse" then
+			for _, s1 in pairs(fourdirs) do
+				local p1 = self._pos+s1
+				if not game:get_figure(p1) then
+					local p2 = p1+s1
+					local n = s1:transpose()
+					for _, s2 in pairs{n, -n} do
+						table.insert(t, (p2+s2):assert_bound())
+					end
+				end
+			end
+		elseif self._ptype == "chariot" then
+			for _, step in pairs(fourdirs) do
+				for pos in self._pos:forray(step) do
+					table.insert(t, pos)
+					if game:get_figure(pos) then
+						break
+					end
+				end
+			end
+		elseif self._ptype == "cannon" then
+			for _, step in pairs(fourdirs) do
+				local o = 0
+				for pos in self._pos:forray(step) do
+					if game:get_figure(pos) then
+						o = o+1
+						if o == 2 then
+							table.insert(t, pos)
+							break
+						end
+					end
+					if o == 0 then
+						table.insert(t, pos)
+					end
+				end
+			end
+		elseif self._ptype == "pawn" then
+			table.insert(t, (self._pos+v2d.new(0, self._pside and -1 or 1)):assert_bound())
+			if (self._pos.y <= 4.5) == self._pside then
+				for _, d in pairs{v2d.new(1, 0), v2d.new(-1, 0)} do
+					table.insert(t, (self._pos+d):assert_bound())
+				end
+			end
+		end
+		return t
+	end,
+	_is_selected = function(self)
+		return self._game:get_selection() == self._pos
+	end,
+	_update_appearance = function(self)
+		local tex = {
+			king = 0,
+			advisor = 1,
+			elephant = 2,
+			horse = 3,
+			chariot = 4,
+			cannon = 5,
+			pawn = 6,
+		}
+		local tex = tex[self._ptype]
+		if tex then
+			tex = ("xiangqi_figures.png^[sheet:7x2:%d,%d"):format(tex, self._pside and 1 or 0)
+		else
+			tex = figstex
+		end
+		if self:_is_selected() then
+			tex = tex .. "^(xiangqi_figure_frame.png^[multiply:green)"
+		elseif self._reachable then
+			tex = tex .. "^(xiangqi_figure_frame.png^[multiply:blue)"
+		end
+		self.object:set_properties {
+			textures = {tex, figstex, figstex, figstex, figstex, figstex},
+		}
+		if self._game:get_side() then
+			self.object:set_yaw(math.pi)
+		else
+			self.object:set_yaw(0)
+		end
+	end,
+})
+
+local blankbg = "xiangqi_blank.png"
+minetest.register_node("xiangqi:board", {
+	description = "Xiangqi board",
+	drawtype = "nodebox",
+	node_box = {
+		type = "fixed",
+		fixed = {-1/2, -1/2, -1/2, 1/2, yoff, 1/2}
+	},
+	tiles = {"xiangqi_board.png", blankbg, blankbg, blankbg, blankbg, blankbg},
+	inventory_image = "xiangqi_board.png",
+	groups = {cracky=1},
+	on_construct = function(pos)
+		game.new(pos):setup()
+	end,
+	on_destruct = function(pos)
+		game.new(pos):teardown()
+	end
+})

mod.conf

@@ -0,0 +1,3 @@
+name=xiangqi
+title=Xiangqi
+description=Xiangqi (Chinese chess)