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Delaunay三角形的网格剖分程序

<TITLE>COG 2.1: Local refinement</TITLE>

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<H1>Local refinement</H1>

 <P><IMG SRC="reftest.gif">

 <P>Some simple general (not octree-specific) methods to define a
refinement are defined in the class <B>CogenRefine</B>. At first, we
have to define some other cogenerator. In this example, we use
a simple rectangular geometry:

<PRE>
#include "<A HREF="coglib.hxx">cog/coglib.hxx</A>"
int main()
{
  cogenOctree base = new CogenOctree();
  base-&gt;addBox(wzRegion(2), 0.0,1.0,0.0,1.0);
  base-&gt;addBox(wzRegion(3), 0.1,0.2, 0.7,0.9);
  base-&gt;addBox(wzRegion(3), 0.3,0.4, 0.6,0.8);
  base-&gt;addBox(wzRegion(4), 0.7,0.9, 0.1,0.5);
</PRE>

 <P>Then this base should be used to define the cogenerator of
<B>CogenRefine</B> type:

<PRE>
  cogenRefine gen = new CogenRefine(base-&gt;generator());
  gen-&gt;refinementGlobal(0.2,0.2,0.1);
  gen-&gt;faceRefinementGlobal(0.02,1.0);
</PRE>

 <P>The simple global refinement calls <B>refinementGlobal</B> and
<B>faceRefinementGlobal</B> are available too.  But there are other
interesting possibilities.  For example, some homogeneous refinement
in a given region with <B>refinementInRegion,
refinementIsotropicInRegion</B>:

<PRE>
  gen-&gt;refinementIsotropicInRegion(0.04, wzRegion(3));
  gen-&gt;refinementInRegion(0.04,0.2,0,    wzRegion(4));
</PRE>

 <P>Another variant is refinement in the environment of some point.
The first parameter (the first three in the anisotropic case) define
the refinement in that point: binary subdivision is used until the
edges are below this distance.  The next parameter (the next three)
define a distance parameter which defines the size of the domain
around the point which will be refined.  The last three parameters are
the coordinates of the point. 

 <P>Note that in 2D and 1D all parameters have to be given.

<PRE>
  gen-&gt;refinementIsotropicNearPoint(0.02,  0.1,         1,1,0);
  gen-&gt;refinementNearPoint(0.02,0.1,0,     0.2,0,0,  0,0,0);
</PRE>

<PRE>
//  wzgrid grid = (*base)();
  wzgrid grid = (*gen)();
  grid->write("test.sg");
}
</PRE>