This animation puts you directly in front of the action, so you may better see the three chambers, as well as how the intake ports open and close with the movement of the rotor.

Here you can clearly see how the port shape is affected by various attributes of the engine. First, notice how the opening timing of the port is determined by the "outside" edge of the port, but the closing timing is determined by the "roof" of the port. Next, notice how the traclk of the rotor oil seals (those large rings on the rotor) determine the "inside" placement and shape of the intake port.