openu,1,unit
 a=assoc(1,bytarr(dim,dim,/nozero))
 dens=a(0)
 openu,2,"scale-idl"
 b=assoc(2,bytarr(30,256,/nozero))
 sca=b(0)
 d=size(dens) 
 s=size(sca) 

 if ( color eq 0 ) then begin
	 for i=0, dim-1 do begin
		for j=0, dim-1 do begin
			if (dens(i,j) eq 0) then dens(i,j)=1
		endfor	
	 endfor		
	 max  = 255
	 expo =	2
	 r = findgen(max+1)
	 g = findgen(max+1)
	 for i=0, max do begin
	     g(i) = max * ( 1 - r(i)/max ) ^ expo 
	 endfor
	 tvlct, g, g, g
	 black = 255
	 white = 0
	 ccol_1  = black
	 ccol_2  = black
	 ccol_3  = black
 endif else begin
	 for i=0, dim-1 do begin
		for j=0, dim-1 do begin
			if (dens(i,j) eq 0) then dens(i,j)=1
		endfor	
	 endfor		
	 loadct,color
	 max  = 255
	 r = findgen(max+1)
	 g = findgen(max+1)
	 b = findgen(max+1)

	 tvlct, r, g, b, /get
 	 r(0) = 255
	 g(0) = 255
	 b(0) = 255
	 tvlct, r, g, b

	 black = 1
	 white = 0
	 ccol_1 = white
	 ccol_2 = black
	 ccol_3 = black
 endelse

 set_plot,"x"
 window,1,xpos=450,ypos=28,xsize=dim+350,ysize=dim+200,title="PIC - spacetime"
 xoff=150
 yoff=100
 dist=150
 tv,dens,xoff,yoff
 x = xmin + (xmax-xmin)/d(1)*findgen(d(1))
 y = ymin + (ymax-ymin)/d(2)*findgen(d(2))
 zcrit = 256/zmax
 contour, dens, /noerase, xstyle = 4, ystyle = 4, $
	  level = [level1*zcrit,level2*zcrit,level3*zcrit], $
          c_color = [ccol_1,ccol_2,ccol_3],$
          position = [xoff,yoff,xoff+d(1),yoff+d(2)], $
          /device
 plot, x, y, xstyle = 1, xrange = [xmin,xmax], xtitle = xname, $
          ystyle = 1, yrange = [ymin,ymax], ytitle=yname, $
          charsize = 2,$
          color = black, /nodata, /noerase, /device,$
          position = [xoff,yoff,xoff+d(1),yoff+d(2)]

 xoff = xoff+d(1)+dist
 tv,sca,xoff,yoff
 x = 1.0/s(1)*findgen(s(1))
 y = zmax/s(2)*findgen(s(2))
 contour, sca, /noerase, xstyle = 4, ystyle = 1, yrange = [zmin,zmax],$
        ytitle = zname, charsize = 2, $
	levels = [level1, level2, level3], $
        c_color = [ccol_1,ccol_2,ccol_3], color = black, $	
        position = [xoff,yoff,xoff+s(1),yoff+s(2)], $
        /device

 close,1
 close,2

end