9.2.2. The Ungame’s Game Loop

The ungame creates a Game instance and reimplements paintUnderSprites() and paintOverSprites(). The ungame doesn’t have any sprites, but the game engine invokes paintUnderSprites() and paintOverSprites() anyway, as shown in Example 9.11.

Example 9.11. Painting over and under sprites

Click here to view code image

var game = new Game('ungame', 'gameCanvas'),
    ...

game.paintOverSprites = function () {
   paintNearCloud(game.context, 120, 20);
   paintNearCloud(game.context, game.context.canvas.width+120, 20);
};

game.paintUnderSprites = function () {

   // Background erased by game engine's clearScreen()

   if (!gameOver && livesLeft === 0) {
      over();
   }
   else {
      paintSun(game.context);
      paintFarCloud(game.context, 20, 20);
      paintFarCloud(game.context, game.context.canvas.width+20, 20);

      if (!gameOver) {
         updateScore();
      }

      updateLivesDisplay();
   }
};
...

game.start();