177 lines
5.2 KiB
HTML
177 lines
5.2 KiB
HTML
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<HTML>
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<HEAD>
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<BODY LEFTMARGIN=0 TOPMARGIN=0 BGCOLOR="#FFFFFF">
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<FONT FACE="ARIAL" COLOR="BLACK">
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<IMG SRC="hcreate.GIF" ALT="Internet Development Technologies">
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<BLOCKQUOTE>
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<TITLE>Creating ActiveVRML animations </TITLE>
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</HEAD>
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<BODY>
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<CENTER>
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<H3>Creating ActiveVRML animations <P></H3>
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</CENTER>
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<P>
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This page describes how you can quickly write and
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run your own ActiveVRML scripts. We recommend you get started by looking at the examples we provide.
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<P>
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The primary tool we currently use for directly writing ActiveVRML
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content is a program called the "repl", standing for
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"Read-Evaluate-Print-Loop", similar to the REPL's in
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other interpreted languages. The repl allows ActiveVRML expressions
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to be evaluated, and allows an environment to be built up.
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<P>
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As such, it's very useful for exploratory, incremental programming
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- determining the types of expressions, using partial results
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in subsequent expressions, etc.
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<P>
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The user may type declarations such as
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<P>
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myGeo = geo1 union geo2;;
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<P>
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directly. Note that two semicolons are required after each piece
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of input to the repl.
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<P>
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Also, the repl supports a number of useful "directives"
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preceded with #:
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<UL>
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<LI>#setdir <pathname>;; -- set the current working directory. Example: #setdir "c:\mydir";;
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<LI>#use <filename>;; -- load a file into the environment being built up in the repl. Identifiers in the filename will
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then be available. Example: #use "foo.avr"
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<LI>#add <str>,<id>;; -- add the id to the list of
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behaviors being sampled and displayed. Example: #add "cool", model;;
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<LI>#eval <expression>;; -- directly evaluate an ActiveVRML expression. Example: #eval 1 + 2;;
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<LI>#delete <str>;; -- remove the id from the list. Example: #delete "cool"
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<LI>Ctrl-C -- to exit the repl.
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</UL>
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<P>
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<H2>Using the Repl</H2>
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<P>
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<B>Down loading sample AVR files:</B>
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<P>
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Copy to your local drive the entire \Samples directory from
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\\ACTGFX\ACTIVE
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<P>
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Place your local samples directory anywhere you want.
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<P>
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This directory will copy several AVR files (*.avr) and some resources
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needed. AVR files contain the actual code that gets interpreted
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by the engine via the Repl.
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<P>
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Loading an AVR file into the Repl can be done from a DOS box by typing : repl <filename.avr> The repl is located in "\Program Files\Plus!\Microsoft Internet\A-vrml". <P>
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The Repl window looks like a DOS command window with a > prompt. At the
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beginning of every session you'll get a typical "Welcome
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to ActiveVRML " message on your window.
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<P>
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ActiveVRML is an interpreted language so there is no need to compile
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your scripts. You can also directly type AVR code at the prompt
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and work with the repl interactively.
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<P>
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Load the model by typing:
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#add "cool", model;;
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<P>
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IMPORTANT: Always type 2 semicolons after every # command
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<P>
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This command tells the repl to sample the variable 'model' and
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assigns a tag called "cool".
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<P>
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The general syntax for #add is:
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<P>
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#add <any quoted string>,< identifier>;;
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<P>
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where the identifier is a variable defined in the avr file
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<P>
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<B>To Terminate sampling:</B>
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<OL>
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<LI>At the > prompt type:
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</OL>
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<P>
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#delete <quoted string>;;
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<P>
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Make sure the string matches the one you used for the #add
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<P>
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<B>To exit the Repl:</B>
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<P>
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At the > prompt hit Ctrl+C
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<H2>Sample Repl session</H2>
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<P>
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The following is a sample repl session that displays a somewhat
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interesting image animation. The user types the bold lines.
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The others are response lines.
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<P>
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<TT>Welcome to ActiveVRML version 1.0.</TT>
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<P>
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<TT><B>> redIm = solidColorImage(red);;</B></TT>
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<P>
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<TT>redIm : () (image)</TT>
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<P>
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<TT><B>> w = 0.004 + 0.004 * abs(sin(time));;</B></TT>
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<P>
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<TT>w : () (number)</TT>
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<P>
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<TT><B>> w2 = w * 2;;</B></TT>
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<P>
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<TT>w2 : () (number)</TT>
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<P>
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<TT><B>> blueIm = crop(point2Xy(-w,-w),</B></TT>
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<P>
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<TT><B> point2Xy(w,w),</B></TT>
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<P>
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<TT><B> solidColorImage(blue));;</B></TT>
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<P>
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<TT>blueIm : () (image)</TT>
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<P>
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<TT><B>> model = tile(point2Xy(-w2,-w2),</B></TT>
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<P>
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<TT><B> point2Xy(w2,w2),</B></TT>
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<P>
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<TT><B> blueIm)</B></TT>
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<P>
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<TT><B> over redIm;;</B></TT>
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<P>
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<TT>model : () (image)</TT>
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<P>
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<TT><B>> #add "mine", model;;</B></TT>
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<P>
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(At this point, a window comes up and starts displaying the image
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behavior)
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<P>
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Note here that after every expression evaluation, the system prints
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out the type of the expression. Also, #add only supports certain
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types. Currently, #add supports only image, image*sound, and
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image*sound*sound types. To view a geometry, you must use "renderedImage"
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to render it into an image, and then #add the image.
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<H2>Documentation</H2>
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<P>
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We have a
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<A HREF=earth.htm> tutorial </A> and a
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<A HREF=avrml.htm> full spec reference </A>
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in our Website that you can consult for more details on how to write content.
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<H2>Reporting Problems and Support</H2>
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<P>
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Please send all your bug reports to EnriqueP or ToddFe. Please
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include your system configuration along with detailed steps to
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reproduce the problem.
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<H2>Feature Requests and Suggestions</H2>
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<P>
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We welcome any feedback that you may have. Please send email to
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ColinC and cc. EnriqueP.
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</BLOCKQUOTE>
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</BODY>
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</HTML>
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