Hello,
I would like to use gnuplot to plot my 2d function ch(x,y) [obtained by a pde solver, FreeFem++]. My datafile is structured in this way:


x1 y1 ch(x1,y1)
x2 x2 ch(x2,y2)
x3 y3 ch(x3,y3)
x1 y1 ch(x1,y1)


x4 y4 ch(x4,y4)
...
...
...


...


where I have the value of my function at the 3 vertices of every triangle which constitutes my (triangular, not structured) mesh (see figure here http://i65.tinypic.com/2mydkq9.jpg).
What I would like to get is two separate figures:
1. something like this for the surface, with a colorbar as a legend:
http://i68.tinypic.com/egvkzr.jpg
and
2. something like this for contour lines, with a colorbar as a legend:
http://i67.tinypic.com/msgepg.jpg


How can I get these two figures with gnuplot?
I've tried for example doing the first one :


set palette rgbformulae 33,13,10
set xrange [0: 0.25]
set yrange [0: 0.20]
set view map
splot "mydatafile.txt" w l pal


but the triangles inside are white (not filled with colors) and only the edges of the triangles are coloured.
How about the contour lines?


Thank you in advance,


Keccogrin