Let's now think about making a game with U3d where for example we have a car and 4 wheels.
If you want the wheels to turn and always be positioned ( especially when the car is moving ) I could hypothesize these 2 methods :
  • a script is created in the step to position the wheels based on the new position of the car;
  • creates a 3D file with animated wheels;

Both methods are not 100% good : in fact if the wheels, in addition to turning on themselves, also turn based on the curve that the car is about to make, or if you want to change the wheels during the game with another model, this would not be feasible or at least impractical to do.

With the matrix system you "glue" the 3D files of the wheels to the 3D file of the car. This method is simple and requires little code.
In addition you will be able to take advantage of functions relating to the single 3D object such as rotated, scaled, translated and animations.

Below I give you 2 examples with which you can understand better, download Test Matrices :

Edit : the author of the original car file is called Mirza.