Re: [Stellarium-pubdevel] Issue with OpenGL font rendering and font size on Windows

[Barry G. <bar...@ho...>]

Hi

 

I have noted that font corruption quite a few times following the first run of a new build. However when I examine the compile to make sure I have not had any errors I run Stellarium again. The font has always been correct for subsequent runs and I have not been able to reprduce it.

 

There have been some upgrades to the dejavu font from time to time maybe there is an obscure bug in the font itself 


Barry Gerdes
Beaumont Hills Observatory
S 33' 41' 44"    E 150' 56' 32"



> Date: Sun, 30 May 2010 02:36:55 +1000
> From: scr...@mo...
> To: ste...@li...
> Subject: Re: [Stellarium-pubdevel] Issue with OpenGL font rendering and font size on Windows
> 
> (Following is some more info about this problem - you'll quickly 
> realise who I am...)
> 
> Attached are some examples the of the different fonts and font 
> corruption. I can only reproduce the problem with OpenGL1 and DejaVu 
> Sans, although it occurs randomly. The method I'm using to get the 
> corruption is itself almost corrupt...
> - run
> - start panning (e.g. hold down right arrow key)
> - while panning, press 'v' to show labels
> - while still panning, click mouse (until you hit a star)
> As they say - patience is a virtue. Interestingly, if there is a 
> stutter when the labels are being displayed, I don't think there is 
> ever font corruption - very bizarre.
> 
> I cannot reproduce the problem when using Verdana (that's not to 
> guarantee it won't happen, just that I have tried 50+ times without 
> any corruption). As can be seen in the attachment, Verdana is also 
> much easier to read and looks better - the anti-aliasing is far 
> superior to DejaVu Sans when using OpenGL1.
> 
> I've included OpenGL2 screenshots as a comparison - DejaVu Sans works 
> for me and looks good (the OpenGL2 anti-aliasing is much better than 
> with OpenGL1).
> 
> What to do...
> 
> I recommend changing to Verdana for all Windows builds. It appears to 
> be the most likely solution to several OpenGL1 issues and should be 
> used for all OpenGL1 sessions regardless of whether it was forced or 
> not. There is also a chance it may fix some the OpenGL2 font 
> problems, but that needs to be tested (I don't have any problems). As 
> Verdana is a standard font on Windows (and Mac for that matter) and 
> substitutes closely for DejaVu Sans, why not use it as the default on 
> Windows builds, regardless of OpenGL version? I'd also suggest using 
> something a bit smaller than 16 for the labels - say 14? (16 dominates 
> and doesn't blend well with the other labels - the default app font is 
> 13 but the constellation labels are 16.)
> 
> Should you wish to do a check of the OpenGL version in main.cpp, see 
> the attached patch. (You could alternatively use 
> glGetString(GL_VERSION) in StelMainGraphicsView.cpp, but it has to be 
> after initialising the GL window.)
> 
> Peter
 		 	   		  
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