how to serial.read multiple vars at once [solved]

ok now i got something like this:

//arduino
if(Serial.available()){

    switch (Serial.available()){

    case 'r':
      col[0] = Serial.read();

      break;
      
    case 'b':
      col[1] = Serial.read();

      break;

    }
  }
//processing
  Arduino.write('b');

  Arduino.write(mouseX + 3);

  Arduino.write('r');

  Arduino.write(mouseY + 3);

with the result that I get the blue LED to flicker, but the red one isn't on at all.
hmm in my mind this code makes sense >.<
if receive "b"
receive next value as blue
if receive "r"
receive next value as red

something like:

R(val)B(val)R(val)B(val)R(val)B(val)

regards