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functions.lua

@@ -0,0 +1,103 @@
+function boost_cart:get_sign(z)
+	if z == 0 then
+		return 0
+	else
+		return z / math.abs(z)
+	end
+end
+
+function boost_cart:velocity_to_dir(v)
+	if math.abs(v.x) > math.abs(v.z) then
+		return {x=boost_cart:get_sign(v.x), y=boost_cart:get_sign(v.y), z=0}
+	else
+		return {x=0, y=boost_cart:get_sign(v.y), z=boost_cart:get_sign(v.z)}
+	end
+end
+
+function boost_cart:is_rail(pos)
+	local node = minetest.get_node(pos).name
+	return minetest.get_item_group(node, "rail") ~= 0
+end
+
+function boost_cart:get_rail_direction(pos_, dir_)
+	local pos = vector.round(pos_)
+	local dir = vector.new(dir_)
+	local cur = nil
+	
+	-- Front
+	dir.y = 0
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	-- Down
+	dir.y = -1
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	-- Up
+	dir.y = 1
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	-- Left, right
+	dir.y = 0
+	
+	-- Check left and right
+	local view, opposite, val
+	
+	if dir.x == 0 and dir.z ~= 0 then
+		view = "z"
+		other = "x"
+		if dir.z < 0 then
+			val = {1, -1}
+		else
+			val = {-1, 1}
+		end
+	elseif dir.z == 0 and dir.x ~= 0 then
+		view = "x"
+		other = "z"
+		if dir.x > 0 then
+			val = {1, -1}
+		else
+			val = {-1, 1}
+		end
+	else
+		return {x=0, y=0, z=0}
+	end
+	
+	dir[view] = 0
+	dir[other] = val[1]
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	-- Down
+	dir.y = -1
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	dir.y = 0
+	
+	dir[other] = val[2]
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	-- Down
+	dir.y = -1
+	cur = vector.add(pos, dir)
+	if boost_cart:is_rail(cur) then
+		return dir
+	end
+	
+	return {x=0, y=0, z=0}
+end