Introduction

What is a Lassie Media Library?

An asset library is a compiled SWF movie with all of its internal graphics, animation, and sound configured in a way that is accessible by the Lassie engine so that the symbols in the SWF's library can extracted and used by Lassie. So, think of a library SWF as just a box of assets (images, sounds, etc). Lassie will never show off the box its self, it will just extract its contents and use them to render a game. Since an asset library SWF is never directly displayed, it needs nothing on its timeline save for a list of what library symbols are available to be extracted from it.

Then Versus Now (why are we doing this?)

Flash (AS2) previously restricted access to SWF libraries, making true dynamic library sharing impossible. Because of this, previous Lassie builds forced every media element to load in as an individual SWF movie. Even when multiple objects in a scene used the same SWF file, each object would have to load the media separately. This was especially burdensome for large SWF assets like a game's character movie, which would have to reload each time a new room was viewed, rather than retaining and reusing the loaded character asset.

AS3 has thankfully made library sharing possible. Now graphics, animation and sound can be compiled into a single SWF movie, loaded once, then all those assets can be extracted and used by Lassie as if they were part of Lassie's own library. So, this allows smarter asset management and easier loading. Where a Lassie room in a previous build of the engine might have needed to make 50 separate file requests to pull all the assets required for a single room, Lassie can now load a single library movie for each room and extract all the room's resources from it. Libraries can also be loaded by the game as a whole, making their resources available to all rooms in the game without any redundant loading.

Required Skill Level

Do you know how to use/manage MovieClips within your Flash library? If the answer is "no", then you've got some very basic Flash skills to learn before getting into Lassie. If the answer is "yes", then fear not! You'll be creating, editing, and managing MovieClips just like you always do within Flash; the only difference is that you'll need to tag each clip with a unique identifier, called a "class", then list those identifiers on the first frame of your movie where Lassie can read them. That's it.

Tutorial Vocabulary

There will be several terms used commonly in this tutorial that you should be familiar with before proceeding. Most are pretty basic Flash terms and concepts.

• Document (or "FLA")
  This refers to a Flash-native project file with the extension ".fla".
• Document Library
  Basically, think of this as the Flash Library Panel.
• Library SWF
  This is what we're trying to create. This is a compiled SWF movie that Lassie will load and pull media from. The point of this tutorial is to explain the process involved in configuring a library SWF.
• Symbol
  A "symbol" is anything contained within the document library. The Flash Library Panel shows a list of symbols available for use within the document. Common symbol types are MovieClips, Graphics, and SimpleButtons. Lassie cannot access library symbols until they have been "classified" (keep reading for more details).
• Symbol Name
  Go figure, this is a symbol's name within the document library. It is used exclusively for human-legibility while browsing the Flash Library Panel. It has no technical use or value, so it is important not to confuse a symbol name with a "class name" (keep reading for details).
• Class
  Think of this as an "elevated state" of a library symbol. Once a symbol is given a class, it becomes accessible to Lassie.
• Class Name
  Go figure, this is the name given to a class. However, unlike a symbol name, the class name is of great technical importance. The class name is the identifier that Lassie will use to reference and extract an asset from the library SWF.

For Advance Users

If you have some advanced experience with Flash, you'll probably notice that some of the steps in this tutorial explain the simplest solution, not the most organized, elegant, or best technique. As such, please feel free to build upon this tutorial's basic concepts if you have the background to do so.

And to help advanced users, there are some notes included in this tutorial that specifically target developers with a broader knowledge of Flash and ActionScript-3. Most advanced-user notes are prefaced by a vocabulary test to identify if the information that follows is appropriate for the reader's skill level. If the vocabulary falls outside the range of your AS3 knowledge, don't worry. Move on and don't trouble yourself with excessive technical details.