Some Minor Difficulties with TH2D::Draw()

From: ryan roth (rothr@db.erau.edu)
Date: Thu Nov 19 1998 - 16:39:12 MET


Hello everyone:

I have been developing a GUI application, similiar to the guitest 
program, which allows a user to pull information from an Objectivity 
database, fill a Histogram or Graph object, and then draw it to a canvas.

As I was adding some 2D histogram functionality, I ran into some odd
occurences I was hoping someone on this list could assist me with.

First, I discovered that, if I use the DrawCopy() function of a TH2D, the
plot style always defaults to a scatter plot, no matter what options I
give it.  Draw() works normally, but I would like to use DrawCopy(), as it
would allow the user to rotate Lego and Surface plots.

Second, for some reason I cannot determine, whenever the 'SURF4' option 
is used, the surface always appears as pure white, with no shading 
whatsoever.  To answer the obvious question, yes, I did change the color 
beforehand.  I have been able to get the appropriate shading in a macro, 
but not in this application.

Third, is it possible, in a standard 2D scatter plot, to increase the 
size of the points plotted?  My application, at this time, typically 
involves a number of 'events' on the order of 50-100, rather than thousands.
With the scatter plot points at their default size, the resultant plot is 
very hard to view.

Other question I had regards 1D histograms -- is there some particular 
reason why they cannot seem to be drawn with a smooth curve or line AND 
markers?  Whenever I try (in both macros and in my application) the 
resulting picture only includes markers.

It is possible that some of my difficulties arise from the fact that I am 
not running off of cint -- my application functions as a stand-alone 
program, which simply includes the ROOT libraries and starts using them 
(much like guitest does).  It occured to me that opperating in this 
manner may leave some important variables or objects (which cint might 
automatically define) undeterminate, thus causing some of the library 
functions to operate improperly.  Are there any objects, other than a 
TROOT and a TApplication, which should be declared in a program such as 
this?  I should point out that my main() function is virtually identical 
to the one used in guitest.

Thank you all for you assistance.

Ryan Roth,  New List Member
PHENIX, BNL
rothr@db.erau.edu



This archive was generated by hypermail 2b29 : Tue Jan 04 2000 - 00:34:40 MET