```

PHOTON USE
P
PHI

X1

msg(  PLANT BFC grid and sphere
rot y ang 100;rot z ang 30
surf MARK Z 0.99
gr z m;gr ou y m
gr y m z 1 2
ENDUSE
>>>>>>>>>>>>>>>>>>>>>> Comment begins >>>>>>>>>>>>>>>>>>>>

DISPLAY
This input  demonstrates  that  the   "drilling-milling"
technique  available  in PLANT can be used also with BFC
grids.  The combination of BFC  with  blocking-off  some
cells  to fit extra geometrical features,  may bring the
number of practical advantatges.

In this  case  the   sphere   and   cylinder   will   be
"drilled-out" in the beam of asteroidal cross section.
ENDDIS

PLANT information :
* Data input groups used: 6, 19
* Ground groups planted : 1, 19-2, 19-6
* Headings used  : MXYZ??, SC06??
* Functions used : SPHERE, XYCIRC
* Commands used  : REGION

<<<<<<<<<<<<<<<<<<<<<<< Comment ends <<<<<<<<<<<<<<<<<<<<<
TEXT( Drilling star-shaped space

GROUP 6. Body-fitted coordinates or grid distortion
nx=28;ny=20;nz=40
bfc=t
CSG1=PHI;CSG2=XYZ;lsweep=1;IDISPA=1
SOLVE(MARK)
FIINIT(MARK)=0.
NAMSAT=MOSG

PLANTBEGIN
real(twopi,littler)
littler=1.0;twopi=2.0*3.14157
RG(1)=TWOPI
** Calculate BFC star-shaped grid
XC=:LITTLER:*FLOAT(J-1)/FLOAT(NY)*\$
COS(RG(1)*FLOAT(I-1)/FLOAT(NX))**3
YC=:LITTLER:*FLOAT(J-1)/FLOAT(NY)*\$
SIN(RG(1)*FLOAT(I-1)/FLOAT(NX))**3
ZC=5*FLOAT(K-1)/FLOAT(NZ)
** Drill the sphere
MARK=SPHERE(1.,0.,0.,4.0,0.6)
** Drill the cylinder
MARK=XYCIRC(1.,0.,0.,0.3)
REGION(,,,,9,20)
>>>>>>>>>>>>>>>>>>>>>> Comment begins >>>>>>>>>>>>>>>>>>>>
The use  of  SPHERE,  XYCIRC   and   other   geometrical
functions is similar to cartesian cases.  The difference
is  that  arguments  must  be  specified  in  terms   of
reference cartesian coordinate system.  The latter is of
routine use for all BFC problems.
<<<<<<<<<<<<<<<<<<<<<<< Comment ends <<<<<<<<<<<<<<<<<<<<<
PLANTEND

dmpstk=t
DISTIL=T
EX(MARK)=2.800E-01
LIBREF=601
STOP
```