Game Development Reference
In-Depth Information
Summary
In the chapter we got started with 2D rendering using the long-awaited canvas API.
We looked at the various drawing functions available to us through the canvas ren-
dering context, which includes drawing simple lines and shapes, drawing images from
an external image source, pixel manipulation, and image extraction, which allows us
to save the image from the canvas back to the user's file system.
We also looked at the new threading system available to us through the web worker
interface. This allows us to free up the user interface thread, while we perform long
lasting tasks that would otherwise lock up the interface, and cause the browser to
display a non-responsive page alert. Unfortunately, there are a few limitations to web
workers, since there is no shared memory between workers, and no DOM associated
with, or allowed in a worker thread. Still, much can be done with this magnificent new
feature of HTML5.
The other HTML5 specific API that we covered in the chapter was the offline applica-
tion cache. Through this mechanism, we can save specific assets from a web server,
storing it as a fast, highly available cache, powered by the user's browser. The spe-
cific assets that are saved by the browser are specified by a manifest file, while it is
a simple text-based file, and must be served by the server with the
text/cache-
manifest
MIME type.
Finally, we looked at two new additions to the JavaScript language that make game
development more efficient and exciting. The first of these two features is
re-
questAnimationFrame
, which allows us to render all of our content in a single,
synchronized call, managed by the browser itself. This is often the best way possible
to render all of our graphics, since the browser can highly optimize the rendering pro-
cess. The second feature is the typed array data type, which allows for much efficient
data storage and access. This is especially attractive to game development because
of the extra boost in performance we can get, just by using this new data type, even
though it looks and behaves almost 100% the same as regular arrays. Thus, writing
new code using typed arrays should include no learning curve whatsoever, as porting
existing code that uses arrays is a real treat.
In the next chapter we continue working on the Snake game, making it more robust
and feature rich. We'll learn about four more HTML5 APIs, namely sessionStorage,
localStorage, IndexedDB, and web messaging.
