c
c Signed distance for multiple spheres.
c This simple function is only correct for non-overlapping
c domains.
c Use mutiple level set functions to model complex bodies!
c
c Copyright (C) 2003-2007 California Institute of Technology
c Ralf Deiterding, ralf@amroc.net
c
c =====================================================
subroutine ls(maxmx,maxmy,maxmz,mbc,mx,my,mz,x,y,z,
& dx,dy,dz,phi,t)
c =====================================================
implicit double precision (a-h,o-z)
c
include "cuser.i"
c
dimension phi(1-mbc:maxmx+mbc, 1-mbc:maxmy+mbc,
& 1-mbc:maxmz+mbc)
dimension x(1-mbc:maxmx+mbc),y(1-mbc:maxmy+mbc),
& z(1-mbc:maxmz+mbc)
c
do 60 i = 1-mbc, mx+mbc
do 60 j = 1-mbc, my+mbc
do 60 k = 1-mbc, mz+mbc
phi(i,j,k) = dsqrt((x(i)-xm(1,1))**2
& +(y(j)-xm(2,1))**2+(z(k)-xm(3,1))**2)
& - rd(1)
do ns = 2, NSph
phitest = dsqrt((x(i)-xm(1,ns))**2
& +(y(j)-xm(2,ns))**2+(z(k)-xm(3,ns))**2)
& - rd(ns)
if (dabs(phi(i,j,k)).ge.dabs(phitest))
& phi(i,j,k) = phitest
enddo
60 continue
c
return
end
c