From 46bac9d063ca41c740453a39bfddc0b378f40563 Mon Sep 17 00:00:00 2001
From: Wuzzy <Wuzzy2@mail.ru>
Date: Tue, 21 Dec 2021 22:00:51 +0100
Subject: [PATCH] Add support for laser mirroring

---
 mods/lzr_laser/blocks.lua  | 22 ++++++++++++++++++++++
 mods/lzr_laser/physics.lua | 33 +++++++++++++++++++++++++++------
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/mods/lzr_laser/blocks.lua b/mods/lzr_laser/blocks.lua
index 2df2d9e..0fdb4ad 100644
--- a/mods/lzr_laser/blocks.lua
+++ b/mods/lzr_laser/blocks.lua
@@ -43,6 +43,28 @@ lzr_laser.get_mirror_dirs = function(param2)
 	return dir_input, dir_output
 end
 
+-- Mirror a laser that touches a mirror at mirror_pos with a laser coming towards
+-- the mirror with the laser_dir direction (direction vector).
+-- Returns the "output direction" of the laser or false if can't get mirrored.
+lzr_laser.get_mirrored_laser_dir = function(mirror_pos, laser_dir)
+	local mirror = minetest.get_node(mirror_pos)
+	local mirror_group = minetest.get_item_group(mirror.name, "mirror")
+	if mirror_group == 0 then
+		return false
+	end
+	local reverse_laser_dir = vector.multiply(laser_dir, -1)
+	local mirror_dir_in, mirror_dir_out = lzr_laser.get_mirror_dirs(mirror.param2)
+	if not mirror_dir_in then
+		return false
+	end
+	if vector.equals(reverse_laser_dir, mirror_dir_in) then
+		return mirror_dir_out
+	elseif vector.equals(reverse_laser_dir, mirror_dir_out) then
+		return mirror_dir_in
+	end
+	return false
+end
+
 minetest.register_node("lzr_laser:mirror", {
 	description = S("Mirror"),
 	paramtype2 = "facedir",
diff --git a/mods/lzr_laser/physics.lua b/mods/lzr_laser/physics.lua
index d0156a9..77ce563 100644
--- a/mods/lzr_laser/physics.lua
+++ b/mods/lzr_laser/physics.lua
@@ -10,7 +10,8 @@ function lzr_laser.add_laser(pos, dir)
 		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
+		pos = vector.add(pos, dir)
+		return pos, dir
 	-- Laser through laser (laser intersection)
 	elseif minetest.get_item_group(node.name, "laser") > 0 then
 		local dirnum = minetest.get_item_group(node.name, "laser")
@@ -21,7 +22,21 @@ function lzr_laser.add_laser(pos, dir)
 
 		local place_dirstring = lzr_laser.bitwise_or(dirstring_old, dirstring_new)
 		minetest.set_node(pos, {name="lzr_laser:laser_"..place_dirstring})
-		return true
+		pos = vector.add(pos, dir)
+		return pos, dir
+	-- Mirror laser
+	elseif minetest.get_item_group(node.name, "mirror") > 0 then
+		local mirror_dir = lzr_laser.get_mirrored_laser_dir(pos, dir)
+		if mirror_dir then
+			-- Activate mirror node
+			minetest.set_node(pos, {name="lzr_laser:mirror_on", param2 = node.param2})
+			-- Set new pos and dir
+			pos = vector.add(pos, mirror_dir)
+			dir = mirror_dir
+			return pos, dir
+		else
+			return false
+		end
 	-- Anything else: fail
 	else
 		return false
@@ -52,23 +67,29 @@ function lzr_laser.travel_laser(pos, dir)
 			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)
+		i_pos, dir = lzr_laser.add_laser(i_pos, dir)
+		if i_pos == false then
+			cond = false
+		end
 	end
 end
 
 -- Remove all lasers in area and disable all laser blocks
 function lzr_laser.clear_lasers_in_area(pos1, pos2)
+	-- Remove lasers
 	local lasers = minetest.find_nodes_in_area(pos1, pos2, {"group:laser"})
 	minetest.bulk_set_node(lasers, {name="air"})
+
+	-- Disable laser blocks (mirror, etc.)
 	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 block_pos = laser_blocks[b]
+		local block = minetest.get_node(block_pos)
 		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})
+				minetest.set_node(block_pos, {name=inactive, param2=block.param2})
 			end
 		end
 	end