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