Hi guys, really new to processing and have a question. I have this sort of pac-man head reversing itself as soon as it reaches the width of the screen but I would also like it to rotate 180 degrees for the  mouth to face the correct direction. I've tried the push and popMatrix() but it seems to not rotate it correctly?

1. boolean isOpening = true;
   boolean isLooping = true;
   boolean insideFrame = true;
   float mouthAngle = 0;
   float mouthChange = 0.025;
   int c = 255;
   int x = width/2;
   int y = 250;
   
   void setup() {
   size (500, 500);
   }
   
   
   
   
   void mouseClicked() {
   if (isLooping) {
   noLoop();
   isLooping = false;
   }
   else {
   loop();
   isLooping = true;
   }
   }
   
   
   void draw() {
   background(255); //to clean screen
   fill (c);
   
   if (isOpening) {
   c -= 2;
   }
   else {
   c += 2;
   }
   
   if (isOpening) {
   mouthAngle += mouthChange;
   }
   else {
   mouthAngle -= mouthChange;
   }
   
   if (mouthAngle >= 3.142/4 || mouthAngle <= 0) {
   isOpening = !isOpening;
   }
   //opening & closing limits
   
   //check if shape is within frame, if not then turn back
   if (insideFrame) {
   x = x+1;
   }
   else {
   x = x-1;
   }
   
   pushMatrix();
   if (!insideFrame) {
   
   
   translate (x, y);
   rotate (PI);
   }
   
   
   if (x <= 0 || x >= 500) {
   insideFrame = !insideFrame;
   }
   
   arc(x, y, 100, 100, mouthAngle, TWO_PI-mouthAngle, PIE);
   popMatrix();
   }