Hi,

does anyone know how I can achieve drawing triangle on level sets of some 3d function (something like on this image in gnuplot? When I tried doing this after reading some tutorials:

gnuplot> set border 15 front linetype -1 linewidth 1.000
gnuplot> set logscale z 10
gnuplot> set view map
gnuplot> set isosamples 60, 60
gnuplot> unset surface
gnuplot> set contour base
gnuplot> unset clabel
gnuplot> set style data lines
gnuplot> set ticslevel 0
gnuplot> set noztics
gnuplot> set title "Trwa symulacja"
gnuplot> set xlabel "x"
gnuplot> set xrange [ * : * ] noreverse nowriteback
gnuplot> set ylabel "y"
gnuplot> set zlabel ""
gnuplot> set yrange [ * : * ] noreverse nowriteback
gnuplot> set zrange [ * : * ] noreverse nowriteback
gnuplot> splot [-10.5:10.5] [-10.5:10.5] x**2 +y**2 with lines lc rgb "#000000"
notitle,\
>'-' with lines notitle
input data ('e' ends) > 5.39703780733842 0.424994542694183 29.3086374551602
input data ('e' ends) > -4.80045950473308 -8.66307635892326 98.0933034571172
input data ('e' ends) > -3.56740563691939 3.31903046267993 23.7423461905216
input data ('e' ends) > 5.39703780733842 0.424994542694183 29.3086374551602
input data ('e' ends) > e

But I'm still getting warning: "Cannot contour non grid data. Please use "set dgrid3d".".