Dear all,

On the caves’ survey I draw, I am often adding the altitude of points that are characteristic in the cave by using the point « altitude ». I find that really great and I want to keep it.

However, I received several remarks from my co-cavers/surveyors that this is not quite readable, and that they would prefer if I can also add the depth since the entrance at those points. I can do it manually with the point label, but for a complex system, that will be a pain to maintain each time we add a new survey or a connection with an other cave previously unconnected.

I thus tried to add a new user defined point (u:prof) based on the present altitude definition. However I am really not a mpost guru and I am facing two problems. Here is the code I wrote :

###### New point depth ######

code metapost

def p_u_prof (expr pos, R, S, A) =

T:=identity aligned A scaled 1.5S rotated R shifted pos;

# calcul of the depth of the point: altitude of the point - altitude max of the cave

# (it will be better with the altitude of the main entrance

# defined by the option -entrance of the survey block)

depth := \thaltitude - \cavemaxz;

# Print the label

begingroup

interim defaultscale:=1;

label (btex {-- } depth {m --} etex, (0, 0)) transformed T withcolor(0.5,0.,0.);

# 1) Why is profondeur value NOT printed ? Where is the error ?

endgroup;

enddef;

initsymbol("p_u_prof")

endcode

##############################

The problem is that this point will print the text "-- depth m --", but not the value of the depth. I suspect that :

the depth calcul may not be accurate?
the way I call the variable depth is not accurate?

Does anyone has a clue for that problem?

My second problem/question deals with the way to calculate the depth. Here I try to calculate it by using the maximum altitude of the cave (\cavemaxz). But it should be better if I use the altitude of the main entrance if it exists. But I did not find if there is such a varaible already defined. Does anyone knows how to do that ?

Cheers,

Xavier