add basic sounds

.gitignore

@@ -0,0 +1,3 @@
+.settings/*
+.project
+.buildpath

init.lua

@@ -18,6 +18,7 @@ local cart = {
 	old_pos = nil,
 	old_velocity = nil,
 	pre_stop_dir = nil,
+	sound_handle = nil,
 	MAX_V = 6, -- Limit of the velocity
 }
 
@@ -234,6 +235,19 @@ function cart:on_step(dtime)
 	if not cart_func.v3:equal(self.velocity, {x=0,y=0,z=0}) then
 		self.pre_stop_dir = cart_func:velocity_to_dir(self.velocity)
 		
+		if self.sound_handle == nil then
+      self.sound_handle = minetest.sound_play("vcarts_cart_sound", {
+        object = self.object,
+        max_hear_distance = 2,
+        loop = true,
+        gain = 0.4,
+      })
+    end
+		
+		elseif self.sound_handle ~= nil then
+		  minetest.sound_stop(self.sound_handle)
+		  self.sound_handle = nil
+		  
 		-- drop cart if its position is incorrect (e.g. floating in air)
 		elseif cart_func:is_rail(pos) == false then
 			self.object:remove()