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<CENTER><B>3D</B></CENTER>
Creating a cutting-edge engine<BR>
<A HREF="Engine01.shtml">01 - Design document</A><BR>
<A HREF="Engine02.shtml">02 - Overall structure</A><BR>
<BR>
<A HREF="Engine03.shtml">03 - Binary Space Partitioning</A><BR>
<A HREF="Engine04.shtml">04 - Constrctive Solid Geometry</A><BR>
<A HREF="Engine05.shtml">05 - Portals</A><BR>
<A HREF="Engine06.shtml">06 - Possible Visible Set</A><BR>
<A HREF="Engine07.shtml">07 - Radiosity lighting</A><BR>
<!--A HREF="Engine08.shtml"-->08 - Mirrors</A><BR>
<BR>
<!--A HREF="Dictionary.shtml"-->Dictionary of 3D terms</A><BR>
<BR>
<CENTER><B>OTHER</B></CENTER>
<!--A HREF="GeneticAlgorithm.shtml"-->A Genetic Algorithm</A><BR>
<A HREF="Line01.shtml">Line drawing</a><BR>
<!--A HREF="Line02.shtml"-->Line clipping</a><BR>
<!--A HREF="Line03.shtml"-->Line antialiasing</a><BR>
<!--A HREF="Line04.shtml"-->Line thickening</a><BR>
<!--A HREF="Line05.shtml"-->Line curving</a><BR>
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<A HREF="ResourcesWeb.shtml">Resources on the web</A><BR>
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<B>Bad</B>: see shamon<BR>
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<FONT FACE="arial"><B>02 - Overall structure</B></FONT>
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The overall structure of your program is absolutely crucial and must be thought out even before you
start up the IDE/text editor/stone table and chisel. As it is said in <A HREF="../tao.html">The Tao
of Programming</A>:
<BLOCKQUOTE>"When I first began to program I would see before me
the whole program in one mass. After three years I no longer saw
this mass. Instead, I saw subroutines. Now I see nothing."</BLOCKQUOTE>
What it means is that once you develop the intuitive understanding you will auto magically take into
consideration the overall structure and work with the flow, thus making your life a lot easier.<BR>
<BR>
If you're a self taught programmer then it's very likely no one ever taught you how to structure your
software code. Well today you're in luck, 'cause I'm going to let the secret out. <I>ALL</I>
programs, to one degree or another, have the same fundamental parts:<BR>
<UL>
<LI><B>The Model</B> is the set of all data that you are manipulating in the program. In the case of
a 3D engine it would include the world model, the sprites, the motion paths, the sound effects, the
world events, etc... Properly designed, (IMHO) the model shouldn't have to contain any
platform-specific code.
<LI><B>The Graphic User Interface (GUI)</B> is all parts of the program that provide an interface with
the user. In the simplest case it's a command prompt. In our case it's probably a full screen,
multimedia extravaganza with fully configurable input devices and a plethora of different rendering
and sound systems. Simply put, it's a user-friendly way of drawing the polys and playing the sounds.
<LI><B>The Controller</B> is the part of the program that provides a connection between the GUI and the
model. It is the entry point into the program and basically runs the whole show.
</UL>
Each of these sections should be as independent of each other as possible. In other words the GUI
should never call the model, the model should never call the GUI and neither should call the controller.
It may turn out that it is unavoidable, but try your damnest not to break this rule because if you do
you develop a <I>cyclic dependency</I> which is BAD.<BR>
<BR>
At the time I wrote this page, my engine structure looked, in part, like this:<BR>
<BR>
<p align="center">
<IMG SRC="0201.jpg" WIDTH="470" HEIGHT="471" ALT="zViewer engine design" BORDER="0"><BR>
</center>
<BR>
Which is nothing compared to my original idea:<BR>
<BR>
<p align="center">
<IMG SRC="0202.jpg" WIDTH="350" HEIGHT="350" ALT="zViewer original engine design" BORDER="0"><BR>
</p>
<BR>
Technically speaking you <I>should</I> develop the controller, then the model, then the GUI. However,
reality says you should test at various stages so you have to develop each <i>in part
simultaneously</i>. It would be very very difficult to develop first one and then the other. Ever
try to debug 500k of code? Two words: nervous breakdown.<BR>
<BR>
But enough of all these preliminaries, let's skip to the last chapter and learn something really
mind blowing!<BR>
<BR>
<a href="#top">Back to the top</a>
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<B>PREV: <A HREF="Engine01.shtml">The Design document</A></B><BR>
<B>NEXT: <A HREF="Engine03.shtml">Binary Space Partitioning</A></B><BR>
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