mainwzsegmenttest.html

Delaunay三角形的网格剖分程序

<TITLE>WZ 1.1: Segments</TITLE>
<h1>Segments</h1>

<PRE>
#include "<A HREF="wzsegment.hxx">wzsegment.hxx</A>"
#include &lt;fstream.h&gt;
</PRE>

 <P>There are four different types of segments: regions
(<B>wzRegion</B>), faces (<B>wzFace</B>), edges (<B>wzEdge</B>) and
vertices (<B>wzVertex</B>).  Essentially these are simply numbers.

 <P>The simplest way is to use them only as indices initialized with
positive numbers.  Note that region 0 is forbidden.  The default
region 1 has usually the meaning "outside", and therefore in the most
common standard applications with only one body we have slightly
unusual numbers for the regions: the body itself ("inside") has region
number 2 instead of 1.  (You are free to make other choices, but 0
remains forbidden and a region outside is usually necessary in the
geometry description.)

<PRE>
void test()
{
  wzSegment outside  = wzRegion(1);
  wzSegment inside   = wzRegion(2);
  wzSegment boundary = wzFace(1);
  now(boundary.isFace());
  now(outside.isRegion());
  now(outside.index()==1);
}
</PRE>

<H2>Names, Materials, Colors</H2>

 <P>Now, it is possible to assign names, materials, and colors to the
segments.  This requires a segment description.  That means, if we
want to use the
 <A HREF="maingridviewtest.html">colors</A> or
 <A HREF="mainmaterialtest.html">materials</A>, it is <b>required</b>
to declare at least one instance of the class
<b>wzSegmentDescription</b> which assigns colors and material numbers
to regions.  There is a class wzDefaultSegmentDescription which may
be used.

 <P>But for your own application we recommend to use your own segment
description in the following way:

 <ol>
 <li> define a derived class of wzSegmentDescription (wzSegmentTest)
 <li> include all materials, boundary conditions and material functions
into this class.
 <li> create one instance (test_segments)
 </ol>

<h2>Test Example for Segment Description</h2>

We need an instance of the class <B>wzSegmentDescription</B>. This
instance has to be initialized before the call of
 <A HREF="maingridviewtest.html">graphics</A>.   Another example of
application of the segment description is its use to write out
 <A HREF="mainmaterialtest.html">material numbers</A> instead of
region numbers.

 <P>For this purpose we define here a derived class
<B>wzSegmentTest</B> so that the constructor initializes the colors.
Then we declare one instance <B>test</B> as a static variable.

<PRE>
#include "<A HREF="wzsegment.hxx">wzsegment.hxx</A>"

class test_segment_description: public wzSegmentDescription
{
public:
	test_segment_description();
};
</PRE>

 <P>Now, the names, materials and colors have to be defined.
Colors and materials may be defined separately.

<PRE>
test_segment_description::test_segment_description()
:wzSegmentDescription()
{
  int i; wzRegion r,r1,r2,r3; wzFace f,f1,f2; wzEdge e; wzVertex v;
  r  = wzRegion("air","#099011311");
  r1 = wzRegion("ground","#210");
  r2 = wzRegion("water");
  r3 = wzRegion("layer1",r1);
  f  = wzFace("Dirichlet b.c.","#099011311");
  f1 = wzFace("natural b.c.");
  f2 = wzFace("Neumann b.c.");
  e = wzEdge("default edge");
  v = wzVertex("default vertex");
  wzRegion( 2).color()="#00a";
  wzRegion( 3).color()="#320";
  wzFace  ( 2).color()="#201000";
  wzFace  ( 3).color()="#000300611";
  wzEdge  ( 1).color()="#099011311";
  wzVertex( 1).color()="#099011311";
}
</PRE>

 <P>Now, before the output one instance of <B>wzSegmentTest</B> has to
be defined. This calls the constructor. Only after this, the colors,
names and materials are appropriately initialized.

<PRE>
test_segment_description test_segments;
</PRE>

<A NAME="End"> <hr></A>

<PRE>
int main()
{
  test_segments.print();
  test();
  fine();
}
</PRE>

 <P>You can test this code with:
 <BR>
 <BR><B>&gt;cog main wzsegment</B>
 <BR>
 <BR>The output should be:
 <BR>Region air                  (#099011311)
 <BR>Region ground               (#000000a00)
 <BR>Region water                (#300200000)
 <BR>Region layer1               (#200100000)
 <BR>Face   Dirichlet b.c.       (#099011311)
 <BR>Face   natural b.c.         (#200100000)
 <BR>Face   Neumann b.c.         (#000300611)
 <BR>Edge   default edge         (#099011311)
 <BR>Vertex default vertex       (#099011311)
 <BR>success