add input.get_mouse_delta()

doc/en/scripting/builtins/libinput.md

@@ -48,6 +48,12 @@ input.get_mouse_pos() --> {int, int}
 
 Returns cursor screen position.
 
+```lua
+input.get_mouse_delta() --> {int, int}
+```
+
+Returns cursor movement delta.
+
 ```lua
 input.get_bindings() --> strings array
 ```

doc/ru/scripting/builtins/libinput.md

@@ -48,6 +48,12 @@ input.get_mouse_pos() --> {int, int}
 
 Возвращает позицию курсора на экране.
 
+```lua
+input.get_mouse_delta() --> {int, int}
+```
+
+Возращает дельту позиции курсора.
+
 ```lua
 input.get_bindings() --> массив строк
 ```

src/logic/scripting/lua/libs/libinput.cpp

@@ -82,6 +82,12 @@ static int l_get_mouse_pos(lua::State* L) {
     return lua::pushvec2(L, engine->getInput().getCursor().pos);
 }
 
+static int l_get_mouse_delta(lua::State* L) {
+    if (engine->isHeadless())
+        return 0;
+    return lua::pushvec2(L, engine->getInput().getCursor().delta);
+}
+
 static int l_get_bindings(lua::State* L) {
     if (engine->isHeadless())
         return 0;
@@ -171,6 +177,7 @@ const luaL_Reg inputlib[] = {
     {"mousecode", lua::wrap<l_mousecode>},
     {"add_callback", lua::wrap<l_add_callback>},
     {"get_mouse_pos", lua::wrap<l_get_mouse_pos>},
+    {"get_mouse_delta", lua::wrap<l_get_mouse_delta>},
     {"get_bindings", lua::wrap<l_get_bindings>},
     {"get_binding_text", lua::wrap<l_get_binding_text>},
     {"is_active", lua::wrap<l_is_active>},