Hello Patrick,

On 11/01/2011 06:03 PM, Patrick Hartling wrote:
> I have been evaluating the use of FTGL (most likely the SVN trunk
> version) with OpenSG 2, and I was wondering if anyone has
> recommendations for the integration process. I looked at what OpenSG 1.8
> has for FTGL support, and it seems fairly straightforward. Is that
> approach still fairly reasonable for OpenSG 2?

if you mean, "will it still work this way" then yes, perhaps with some 
small adjustments.

> While reviewing the 1.8 code, I noticed that there was some hope many
> years ago that OpenSG 2 would include revamped support for text display.

Someone please correct me if I get the history wrong here, but I think 
the revamped text support mentioned in the Contrib/FTGLText readme is 
actually what is in OpenSG today.

> Did that work get done, or is there still interest in refining that area
> of OpenSG? We need something that I believe requires more flexibility
> than is currently offered by the OpenSG text features. I am no expert
> with text display, but I may be able to contribute something to OpenSG
> when my work is complete.
>
> To summarize, my goals for the work that I need to do are as follows:
>
>     * Support all rendering techniques implemented by FTGL while
>       allowing custom rendering through user-supplied subclasses of
>       FTGlyph. Custom glyph rendering is the main thing that we need
>       beyond what seems possible with OpenSG's current text support.

what does custom glyph rendering mean in this context? Do you want to be 
able to render glyphs that are not part of a font? Apologies if this is 
a term with a specific meaning in "FTGL speech", I don't know that lib 
very well.

>     * Full Unicode support using UTF-8 as the input encoding—unless
>       ICU4C or something equivalent were added as a dependency. I do not
>       want to get into the mess of wchar_t and std::wstring as that has
>       not worked out well for me in the past. This will most likely
>       require multi-font support to allow for fallbacks when a needed
>       glyph is not supplied by the primary font in use.

AFAIK you can just feed a UTF-8 string to the OpenSG font functions and 
as long as there are appropriate glyphs in the font it will work. I 
don't think there is any fallback atm, but that would be an interesting 
addition.

>     * Provide good performance and scalability. In our use cases, we
>       could very easily have hundreds or thousands of text billboards,
>       and we need to make efficient use of texture memory. While I have
>       no plans to limit things to texture-mapped text, that will be our
>       focus. Nevertheless, FTGL already implements multiple techniques,
>       and I see no need to apply limitations in that regard.

with the current text code you should need only have on TextTXTFace 
object per font (meaning one texture) and can have arbitrary amounts of 
text generated from it. So, I'm not sure what causes you to be concerned 
about memory usage with the existing text implementation, can you give 
more details?
I'm not sure if anyone strongly cares for anything other than texture 
mapped text these days.
A really nice addition would be to support something like 
<http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf>
 
which from the images in the paper would improve the looks of magnified 
text quite a bit.

> Basically, we want to be able make use of what FreeType, FTGL, and
> OpenSG offer without being impeded by abstraction layers. That does not
> necessarily mean that the API will be harder to use than what OpenSG
> provides now, but my conclusion is that we need something new to do what
> we want.

Hmm, I'm not sure I've fully understood where you are expecting large 
obstacles in making OpenSG's text support do what you want. As far as 
FTGL is concerned I'm somewhat indifferent about it, a downside is that 
is manages its own OpenGL state so is somewhat doing it's own thing 
besides OpenSG. Then again I don't know it well and it may have features 
that easily compensate for this?

        Cheers,
                Carsten

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