mainspheretest.html

Delaunay三角形的网格剖分程序

<TITLE>COG 2.1: Spherical coordinates</TITLE>

<H1>COG 2.1: spherical coordinates</H1>

 <P>See <A HREF="mainpolartest.html">the polar coordinate example</A>
for general instructions about curved coordinates.

 <P>The first coordinate is the radius <B>r</B>, then the angle
<B>theta</B> (between -wzPi/2 and wzPi/2), the last is the angle
<B>phi</B> (between -wzPi and wzPi).

 <P>The example below creates a spherical grid with various
subregions which are box-like in these coordinates.  

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

<PRE>
#include "<A HREF="coglib.hxx">cog/coglib.hxx</A>"
int main()
{
  cogenOctree base = new CogenOctree();
  wzIndex i2 = base-&gt;addBox(wzRegion(2), 0.2,0.3,-wzPi/2,-1.0,-wzPi,wzPi);
  wzIndex i3 = base-&gt;addBox(wzRegion(3), 
	0.3,0.4, 0.0,wzPi/2, -1.9, -1.0);
  wzIndex i4 = base-&gt;addBox(wzRegion(6), 
	0.0,0.4, -0.5,0.5, 0.0,1.0);
  base-&gt;setFaceOfBox(wzFace(2),i2);
  base-&gt;setFaceOfBox(wzFace(3),i3);
  base-&gt;setFaceOfBox(wzFace(6),i4);
  base-&gt;refinementGlobal(0.1,0.4, 0.4);
  base-&gt;addPlaneX(0.1);
  base-&gt;addPlaneX(0.25);
  base-&gt;addPlaneX(0.35);
  base-&gt;addPlaneY(wzPi/2);
  base-&gt;addPlaneY(-wzPi/2);
  base-&gt;addPlaneZ(wzPi);
  base-&gt;addPlaneZ(-wzPi);

  wz3dmap sphere = new wz3Dspherical;
  cogenChart gen = new CogenChart(base-&gt;generator(),sphere);

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

<H2>Known Problems</H2>

 <P>"edge problems" sometimes occur if, as in this example, the
critical regions of the coordinates (the axis (r == 0), the origin)
are part of the boundary.  They may be ignored.

 <P>Defining regions outside the domain of definition causes errors.
Be careful if the boundaries are correct: non-negative for X, -wzPi/2
to wzPi/2 for Y, -wzPi to wzPi for Z

 <P>Defining different regions for (phi==wzPi) and (phi==-wzPi) causes
errors.  Be careful that the region numbers coinside there.