Re: [Fenfire-dev] PEG: move glmosaictext to libvob

[Tuomas Lukka]

On Tue, Sep 23, 2003 at 09:46:33PM +0300, Matti Katila wrote:
> > - This is kind of a problem - GLMosaicText is something others
> >   could have used directly while this makes GLMosaicText
> >   dependent on Libvob. Is this a problem?
> > 
> >     RESOLVED: No. The design pressures from Libvob side
> >     did already affect GLMosaicText, moving it away from
> >     the simplest possible solutions. The code will survive,
> >     just not be maintained.
> 
> There are text libraries for opengl and the only user for glMosaicText has 
> been fenfire so this is not a real issue, though.

Quite so.

> > Changes
> > =======
> 
> The interfaces you were proposing seemed to be quite useless without 
> knowing current implementation details. So jvk might be the only person 
> who understands what's going on.

Well, that's the point of PEGging and having you ask questions: to 
ensure others also understand this stuff.

> I added some questions below.

Thank you

> > 
> >     /** The quad coordinates.
> >      * These are stored in a single array so we can, in the future,
> >      * bind and download this to the GPU and just index it,
> >      * along with a vector of offsets (the cumulative sum of
> >      * the advances).
> >      * Stored as groups of 8: x0, y0, x1, y1, tx0, ty0, tx1, ty1.
> >      */
> >     vector<float> coordinates;
> 
> If t[x.y][0,1] are texture coordinates, what are [x,y][0,1] coordinates?

They are the coordinates where the quad should be rendered, i.e. a has a smaller
quad than A. Coordinates of the letter.

Good catch, will fix in PEG.

> > 
> >     /** The advances. Only horizontal text supported here so far.
> >      */
> >     vector<float> advances;
> 
> What?? advances = the advances?

The amount by which the x coordinate should be increased after rendering
a letter.

Good catch, will fix in PEG.

> >     CallGLCode setupCode;
> >     CallGLCode teardownCode;
> > 
> >     void setUp();
> > 
> >     template<class I> void render(I begin, I end);
> > 
> >     void tearDown();
> > 
> >     }
> > 
> > and in Java (operations mapping to the operations of the preceding class)::
> > 
> >     public class QuadFont {
> 
> Missing class documentation?

Will be about the same as for the above - it's just a Java wrapper
for it.

> >     // XXX When needed, add the get() methods.
> > 
> >     /** Store explicitly the GL.Texture objects
> >      * to avoid GC.
> >      */
> >     private GL.Texture[] textures;
> > 
> >     /** Set up the textures to use.
> >      * @param layers The number of textures to be active at a time
> >      * @param texUnits The names of the texunits to bind textures to.
> >      *                      length = layers.
> >      * @param textures The textures. length = layers * number of font pages.
> >      */
> >     public "native" void setTextures(int layers, String[] texUnits,
> >                                 GL.Texture []textures);
> 
> why need to give num of layers if it can be calculated from the size of 
> texUnits array?

Good point. Fixed in the next PEG version. This also changed
to separate texUnits to texture *binding* units and coordinate units.

        Tuomas