Basic laser physics

mods/lzr_laser/blocks.lua

@@ -11,7 +11,8 @@ minetest.register_node("lzr_laser:mirror", {
 		"lzr_laser_mirror_block.png", 
 		"lzr_laser_mirror_hole.png", 
 	},
-	groups = { mirror = 1, dig_immediate = 2 },
+	groups = { mirror = 1, laser_block = 1, dig_immediate = 2 },
+	_lzr_active = "lzr_laser:mirror_on",
 })
 
 minetest.register_node("lzr_laser:mirror_on", {
@@ -25,7 +26,8 @@ minetest.register_node("lzr_laser:mirror_on", {
 		"lzr_laser_mirror_on_block.png", 
 		"lzr_laser_mirror_on_hole.png", 
 	},
-	groups = { mirror = 2, laser = 2, dig_immediate = 2, not_in_creative_inventory = 1 },
+	groups = { mirror = 2, laser_block = 1, dig_immediate = 2, not_in_creative_inventory = 1 },
+	_lzr_inactive = "lzr_laser:mirror",
 })
 
 minetest.register_node("lzr_laser:emitter", {
@@ -39,7 +41,8 @@ minetest.register_node("lzr_laser:emitter", {
 		"lzr_laser_emitter.png", 
 		"lzr_laser_emitter_front.png", 
 	},
-	groups = { emitter = 1, dig_immediate = 2 },
+	groups = { emitter = 1, laser_block = 1, dig_immediate = 2 },
+	_lzr_active = "lzr_laser:emitter_on",
 })
 
 minetest.register_node("lzr_laser:emitter_on", {
@@ -53,7 +56,8 @@ minetest.register_node("lzr_laser:emitter_on", {
 		"lzr_laser_emitter_on.png", 
 		"lzr_laser_emitter_on_front.png", 
 	},
-	groups = { emitter = 2, dig_immediate = 2, not_in_creative_inventory = 1 },
+	groups = { emitter = 2, laser_block = 1, dig_immediate = 2, not_in_creative_inventory = 1 },
+	_lzr_inactive = "lzr_laser:emitter",
 })
 
 minetest.register_node("lzr_laser:detector", {
@@ -67,7 +71,8 @@ minetest.register_node("lzr_laser:detector", {
 		"lzr_laser_detector.png", 
 		"lzr_laser_detector_front.png", 
 	},
-	groups = { detector = 1, dig_immediate = 2 },
+	groups = { detector = 1, laser_block = 1, dig_immediate = 2 },
+	_lzr_active = "lzr_laser:detector_on",
 })
 
 minetest.register_node("lzr_laser:detector_on", {
@@ -81,6 +86,7 @@ minetest.register_node("lzr_laser:detector_on", {
 		"lzr_laser_detector_on.png", 
 		"lzr_laser_detector_on_front.png", 
 	},
-	groups = { detector = 2, dig_immediate = 2, not_in_creative_inventory = 1 },
+	groups = { detector = 2, laser_block = 1, dig_immediate = 2, not_in_creative_inventory = 1 },
+	_lzr_inactive = "lzr_laser:detector",
 })
 

mods/lzr_laser/init.lua

@@ -3,3 +3,4 @@ lzr_laser = {}
 dofile(minetest.get_modpath("lzr_laser").."/util.lua")
 dofile(minetest.get_modpath("lzr_laser").."/laser.lua")
 dofile(minetest.get_modpath("lzr_laser").."/blocks.lua")
+dofile(minetest.get_modpath("lzr_laser").."/physics.lua")

mods/lzr_laser/laser.lua

@@ -65,6 +65,6 @@ for i=1, 64 do
 			type = "fixed",
 			fixed = dirs_to_nodebox(dirs),
 		},
-		groups = { laser = 1, dig_immediate = 3, not_in_creative_inventory = 1 },
+		groups = { laser = i, dig_immediate = 3, not_in_creative_inventory = 1 },
 	})
 end

mods/lzr_laser/physics.lua

@@ -0,0 +1,73 @@
+-- Max. number of steps in the laser travel algorithm
+local MAX_LASER_ITERATIONS = 50
+
+-- Add a laser node to pos with the direction `dir`.
+-- Dir is a direction vector, and only one direction must be set
+function lzr_laser.add_laser(pos, dir)
+	local node = minetest.get_node(pos)
+	-- Laser through air
+	if node.name == "air" then
+		local dirs = lzr_laser.vector_to_dirs(dir)
+		local dirstring = lzr_laser.dirs_to_dirstring(dirs)
+		minetest.set_node(pos, {name="lzr_laser:laser_"..dirstring})
+		return true
+	-- Laser through laser (laser intersection)
+	elseif minetest.get_item_group(node.name, "laser") > 0 then
+		local dirnum = minetest.get_item_group(node.name, "laser")
+		local dirstring_old = lzr_laser.dec2bin(dirnum, 6)
+
+		local dirs_new = lzr_laser.vector_to_dirs(dir)
+		local dirstring_new = lzr_laser.dirs_to_dirstring(dirs_new)
+
+		local place_dirstring = lzr_laser.bitwise_or(dirstring_old, dirstring_new)
+		minetest.set_node(pos, {name="lzr_laser:laser_"..place_dirstring})
+		return true
+	-- Anything else: fail
+	else
+		return false
+	end
+end
+
+function lzr_laser.emit_laser(pos)
+	local node = minetest.get_node(pos)
+	if not minetest.get_item_group(node.name, "emitter") > 0 then
+		minetest.log("error", "[lzr_lazer] lzr_laser.emit_laser was called at invalid pos!")
+		return false
+	end
+	local dir = minetest.facedir_to_dir(node.param2)
+	local i_pos = vector.add(pos, dir)
+end
+
+function lzr_laser.travel_laser(pos, dir)
+	local i_pos = vector.add(pos, dir)
+	local cond = true
+	local i = 0
+	while cond do
+		i = i + 1
+		-- Halt execution for very long loops to prevent freezing the game
+		if i > MAX_LASER_ITERATIONS then
+			minetest.log("error", "[lzr_laser] lzr_laser.travel_laser aborted (too many iterations!)")
+			break
+		end
+		local i_node = minetest.get_node(i_pos)
+		cond = lzr_laser.add_laser(i_pos, dir)
+		i_pos = vector.add(i_pos, dir)
+	end
+end
+
+-- Remove all lasers in area and disable all laser blocks
+function lzr_laser.clear_lasers_in_area(pos1, pos2)
+	local lasers = minetest.find_nodes_in_area(pos1, pos2, {"group:laser"})
+	minetest.bulk_set_node(lasers, {name="air"})
+	local laser_blocks = minetest.find_nodes_in_area(pos1, pos2, {"group:laser_block"})
+	for b=1, #laser_blocks do
+		local block = minetest.get_node(laser_blocks[b])
+		local def = minetest.registered_nodes[block.name]
+		if def then
+			local inactive = def._lzr_inactive
+			if inactive then
+				minetest.set_node(block, {name="inactive", param2=block.param2})
+			end
+		end
+	end
+end

mods/lzr_laser/util.lua

@@ -5,7 +5,7 @@ local LASER_RADIUS = -1/16
 --[[ dirstring: A representation of 6 cardinal directions which are either
 'active' (1) or 'inactive' (0)
 Each direction has the character "1" or "0".
-The characters stand for these directions, in order: -X, +X, -Y, +Y, -Z, +Z
+The characters stand for these directions, in order: -X, -Y, -Z, +X, +Y, +Z
 Example: "101010"
 ]]
 --[[ dirs table: Like dirstring, but in table format. It's a table
@@ -44,6 +44,29 @@ function lzr_laser.dirs_to_dirstring(dirs)
 	return dirstring
 end
 
+function lzr_laser.vector_to_dirs(dir_vector)
+	local dirs = {0,0,0,0,0,0}
+	if dir_vector.x > 0 then
+		dirs[4] = 1
+	end
+	if dir_vector.x < 0 then
+		dirs[1] = 1
+	end
+	if dir_vector.y > 0 then
+		dirs[5] = 1
+	end
+	if dir_vector.y < 0 then
+		dirs[2] = 1
+	end
+	if dir_vector.z > 0 then
+		dirs[6] = 1
+	end
+	if dir_vector.z < 0 then
+		dirs[3] = 1
+	end
+	return dirs
+end
+
 -- Convert number to string in binary form
 -- * num: Number
 -- * minLength: Minimum number of characters the string must have, will
@@ -69,3 +92,18 @@ function lzr_laser.dec2bin(num, minLength)
 	return bin
 end
 
+-- Takes 2 binary numbers (as strings!)
+-- and returns the 'bitwise or' of them (also as string).
+-- Both strings MUST be of equal length.
+function lzr_laser.bitwise_or(bin1, bin2)
+	local len = string.len(bin1)
+	local out = ""
+	for i=1, len do
+		if string.sub(bin1, i, i) == "1" or string.sub(bin2, i, i) == "1" then
+			out = out .. "1"
+		else
+			out = out .. "0"
+		end
+	end
+	return out
+end