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Basic questions about the new graphics system


From: John Swensen
Subject: Basic questions about the new graphics system
Date: Thu, 23 Oct 2008 18:57:41 -0400

As I have started to work on the GTK backend for the OpenGL graphics renderer, I have tried to go back to the mailing lists and read as much as I can about the new graphics system and to look at graphics.cc and fltk_backend.cc to try and figure everything out. Unfortunately, there is a *lot* of code there and was wondering if I could ask a favor. Is there a succinct write-up somewhere of exactly how the the new graphics system works? If not, would one of the people who knows the new system well be willing to spend an hour(s) to make such a document?

In particular, I have the following questions (but I'm sure once these are answered there will be 10 more):

1) I see that FTGL gets compiled in, but I don't see any text, titles, legends, etc. when I try to plot such things. Is there something wrong with my latest build from HG? 2) Along the line of (1), is there a list of which properties are actually implemented? I see that essentially all the properties exist, but which ones actually have an effect on the plot rendering? I guess this applies to both the GNUPLOT and OpenGL backends. 3) For the new graphics subsystem, what is the appropriate way for UI callbacks to modify properties? In my implementation of a GTK OpenGL plot window, when I change the window position or size, or click on a certain point in the window, etc. I need to know how to get that information back into the handle tree in the appropriate manner. It is a simple as modifying the property directly, or is there an interface built in for doing this? Do these take effect immediately, or do they wait until the next iteration of the readline idle loop? 4) Are the event functions implemented yet? What is the proper way to trigger them? 5) For the life of me, I can't get rotation to work with the opengl backend. How should this be done in the proper manner?

I think a 1/2 page to 1 page description of how the different parts of the new graphics subsystem (separating out the handle properties from the OpenGL/Gnuplot backends) would be a great help to me and I think to others who are looking at contributing to the new graphics subsystem.

Thanks.

John Swensen


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