Re: Text properties and FTGL

[John Swensen]

On Oct 29, 2008, at 11:40 AM, John W. Eaton wrote:

> On 29-Oct-2008, John Swensen wrote:
>
> | I think that small subset should also have \dot, \ddot, \hat,  
> \tilde,
> | and maybe a couple others, since these get used quite frequently.
>
> And someone else will of course want \int and \sum and \begin{array}
> and ...  So I think it would be best to simply make it possible to use
> all of TeX, interpreted by TeX itself rather than some kluge.
>
> | Would you be averse to having the two options available at compile
> | time?  That way, for those with systems where LaTeX and libpoppler  
> are
> | available (whether gtk or QT), we could compile in the support for  
> the
> | full interpreter?
>
> That adds maintenance overhead.  I'd say just require TeX for TeX
> markup, and if that is not available, then skip the transformation of
> the TeX parts.
>
> jwe

So I have done a few tests, probably in a very naive way, about  
rendering LaTeX strings to OpenGL.  I think it is going to be  
prohibitively slow.  Using the following code, even a simple equation  
took about 0.6 seconds.  Maybe there is a faster way of doing this.  I  
searched around and couldn't find a way to link against a library for  
rendering LaTeX code.  The pdfcrop step could definitely be made  
faster, since it is a perl script that in turn calls ghostscript.

I also did the conversion to a bitmap with libpoppler (a version with  
no dependency on glib and QT) and drew it with OpenGL and it upped the  
time to about 1.0 seconds.

struct timeval start, stop;
    gettimeofday(&start,NULL);

    // Build up a simple LaTeX file
    std::string baseFilename = "tmplatex";
    std::string logFilename = baseFilename+".log";
    std::string latexFilename = baseFilename+".tex";
    std::string latexFileString = "\\documentclass{article}\n\ 
\usepackage{amsmath}\n\\usepackage{amssymb}\n\\usepackage{amsfonts}\n\ 
\thispagestyle{empty}\n\\begin{document}\n\\begin{equation*}\n" + lbl  
+ "\\end{equation*}\\end{document}\n";
    // TODO: write this to a tmp file
    FILE* fd = fopen(latexFilename.c_str(),"w+");
    fprintf(fd,latexFileString.c_str());
    fclose(fd);

    // Run pdflatex on the file
    std::string pdflatexCmd = "pdflatex -interaction nonstopmode " +  
latexFilename + " > " + logFilename;
    system(pdflatexCmd.c_str());


    // Run pdfcrop on the result
    std::string pdfcropCmd = "pdfcrop --clip --hires " + baseFilename  
+ ".pdf >> " + logFilename;
    system(pdfcropCmd.c_str());

    gettimeofday(&stop,NULL);
    double elapsed = (stop.tv_sec - start.tv_sec) +  
1E-6*(stop.tv_usec - start.tv_usec);
    std::cout << "Elapsed: " << elapsed << std::endl;