Gross, Chapters 22-24

Chapter 22

• P. 525: The Case statement allows you to streamline the handling of several if conditions. Very useful with navigation bars and other standard interface elements.
  
  
• P. 530: Global variables. Note that the global is declared initially in the main movie script. Gross always uses a small "g" to name globals; this is a good practice but not required.
  
  
• P. 533-34: Replacement of the numeric values in the case statement with symbols (preceded by #). This feature makes code considerably more readable. The hash mark (#) introduces symbolic parameters.
  
  
• P. 537: Puppeting sound: which is to say, playing a sound through a Lingo command rather than creating a sprite in a sound channel. This is yet another instance of the Lingo-vs.-score distinction. Remember that you can have sounds both in your score and in Lingo. Puppeted sounds play in channel 1 by default, so it may be necessary to stop the sound already in that channel; or you can puppet the sound in one of the other 8 channels.
  
  
• P. 540: Always shut down a puppeted sound -- puppetSound x, 0 where x represents the sound channel.
  
  
• P. 542: This book was written two years ago. On the current generation of computers, you may see virtually no gain from preloading elements in a movie.

Chapter 23

• P. 546: Key codes differ from ASCII codes; annoying but true. The arrow keys are numbered 123 throgh 126: left, right, down, up.
  
  
• P. 550: Setting the trails property of a sprite causes successive positions to remain on the screen -- useful for drawing lines, as in this project.
  
  
• P. 551: Explanation of the bounding rectangle, a concept we last saw in the Lingo animation demo several weeks back. Note that the dotted-line setting on the tool palette draws invisible outlines, just the thing for bounding rectangles.
  
  
• P. 552: Using constraint of sprite to limit movement.
  
  
• P. 559: The modifications described on this page do not work in Windows, where the ALT key (there is no OPTION) interrupts Director. The same may also be true for Backspace. (It's possible this problem is caused on my particular system by keyboard mappings introduced by other applications.)

Chapter 24

• P. 564: You can use external casts as in effect general libraries of cast members. Unlike (?) libraries in Flash, these can be stored as independent files.
  
  
• P. 565: Gross raises the possibility of storing cast members in external files anywhere on the Internet. Oh GOOD idea...
  
  
• P. 566: But here's a powerful argument for external cast members: you can update Director projectors (though probably not Shockwave movies) by updating the cast member. It is not necessary to recompile the projector.
  
  
• P. 584: Full paths are not required for references to external cast libraries, so long as the library is stored in the same folder as the present movie.
  
  
• P. 588: Gross's example demonstrates how to perform navigation by swapping out cast libraries. This shows how the cast can be used as a powerful tool for modularizing the movie.
  
  
• P. 590: Navigation lists: a list is a structure which in other programming languages would be called an array. In most object-oriented languages, the indices (ordinal numbers) of arrays begin with 0 ("all programmers start with nothing"); not so Lingo, which begins its count at 1. This difference reflects the heritage of Lingo, derived from SmallTalk, a language intended to be easier on non-programmers.
  
  
• P. 591: "Property lists" are in effect arrays of name/value pairs. The list.count feature is equivalent to constructions like array.length in other languages.