set view equal xyz
  set ticslevel 0
  set colors classic

  set xlabel 'x'
  set ylabel 'y'
  set zlabel 'z'

  file = 'grid2.txt'
  splot \
    NaN w p lt 7 pt 5 title 'ambient', \
    NaN w p lt 1 pt 5 title 'blast', \
    file u ($2<1 ?$3:NaN):4:5 w d lt 7 notitle, \
    file u ($2==1?$3:NaN):4:5 w p lt 1 pt 5 notitle

  pause -1 'Press Enter to continue: '