Re: [Plib-users] Couple of fntRenderer questions

[Steve B. <sjb...@ai...>]

Jason Steele wrote:

> I hope I'm not missing something obvious here...

Yep - you are.

> but is there a way to do rotated text (vertical in particular) with fntRenderer/fntTexFont
> in 1.5.1?

Yes....how about:  glRotatef   :-)

Try (for example) adding the following two lines to the end of 'setOpenGLState' in the
PLIB example program 'examples/src/fnt/fnt_test.cxx' and the text will spin quite happily.

In general, the text is drawn relative to the origin in the Z==0 plane - but all of the
usual OpenGL modelview transformations will work so you can apply text to 3D objects
and do all sorts of other amusing tricks.

>  (I'm using fnt.h, but not PUI)

Good - PUI doesn't really support rotated things - but
raw FNT does.
 
> Also, other than the GL_TEXTURE_2D, is there any other effect on the
> OpenGL state that has to be undone after a begin()/puts()/end()
> sequence?   Is there a cleaner way to restore the state other than
> an explicit glDisable(GL_TEXTURE_2D) after I do my font rendering?

State management in OpenGL is a pain.  You can use glPushAttrib/glPopAttrib
to save and restore state - but it's quite slow.

Similarly, saving and restoring state can be quite inefficient if it's
done 'strictly by the book'...glGet{anything} is extremely slow - so
you really have to remember what state you have in your own code and
restore it after.

There really isn't a single 'good' way to do this  :-(
 
> Finally, is there a way to query the inter-line space from either the
> font or the renderer?  getBBox() doesn't quite do what I need.  I see
> in the source there's a hardcoded 1.333*point size increment of the
> cursor's y position for a '\n' (that's the quantity I'm after)
> Is there a way to get this without hardcoding the 1.333 in my
> code?  If not, can I put in a request for this value to be exposed
> through the interface? (allowing modification of it as well would be
> a bonus

There isn't a way to do that right now...there was no way to read out
the amount of 'inter-line-gap' from the TXF file - so I had to choose a
'reasonable' value.  My father was a professional printer - and he said
that a third of the total height of the line is a reasonable rule of thumb.

The best bet is not to let FNT handle the '\n' but to do it yourself and
use glTranslate to position the text.
 
----------------------------- Steve Baker -------------------------------
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