jQuery 1.4 Animation Techniques - Index of

Canvas Animations
Pop quiz – creating canvas-based games
1. In this example a lot of functionality that related to the player's space ship was put
into an onload event handler. Why?
a. Because we cannot interact with an image until it has loaded completely
b. To make the code work correctly in Internet Explorer
c. Because the code runs faster once the image has finished loading
d. To help make our code more modular
2. Why did we set the textAlign property of the canvas to center when writing the
GAME OVER message?
a. Setting the alignment is a prerequisite for writing text to the canvas
b. Because it is easier than working out the width of the text and then setting its
position on the x axis in order to position the text in the center of the canvas
c. To anti-alias the text
d. Because it is more efficient than using padding
Have a go hero – extending the space invaders clone
Our game is a much simpler version of the original space invaders. The original arcade
game had many other features including aliens that fired back at the player's ship, bases to
hide behind, and one off special aliens that appeared randomly throughout the game and
dropped bonuses when hit.
Certainly one thing that the game needs is a scoring mechanism, otherwise there is simply
no incentive to play. Implement a scoring system that tracks a player's score throughout the
game and saves the highest score to the player's machine. This could be done easily with
jQuery and the cookie plugin, or using LocalStorage.
I'd also urge you, as this is the last example of the book, to implement some of the other
missing features, such as giving the aliens the ability to fire back, and adding bases or shields
that the player can hide beneath when the going gets tough.
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