[Opensg-users] Text patches

[Allen B. <al...@vr...>]

Last night Dirk commited the first in a series of changes I have 
proposed to him in the TXFFace interface.  The change he commited adds 
an offset parameter to the geo building interfaces.  I found that I 
commonly wanted to offset the text layout a little bit to position it 
relative to other graphics I had already drawn.  This parameter makes 
that very simple and easy to do.  It also leads into the next proposed 
changed I have....

I found that I really wanted the ability to add text to a geometry node 
multiple times.  As an example, this would allow me to position some 
layed out text in the upper left of a virtual UI and then to position 
some additional text in the lower right without having to create a new 
geometry core and nodes and groups, etc.  I just wanted more text with 
the same font.

While adding support for this, I also began thinking that it would be 
nice if I could specify the color of the text to be added.  Since the 
code just uses a modulating texture environment it is possible to 
support this pretty easily using vertex colors on the glyph quads.

Anyway, I extended/refined the TextTXFFace interface with the following 
methods:  (note: the params are pretty self explanitory so I left those 
comments out of this mail.)

    /** Fills a geometry with a new text. */
    void fillGeo(GeometryPtr &geoPtr, const TextLayoutResult 
&layoutResult, Real32 scale = 1.f,
                 Vec2f offset = Vec2f(0,0), Color3f color = Color3f(1,1,1));

    /** Adds geometry for new text to an existing text geometry. */
    void addToGeom(GeometryPtr &geoPtr, const TextLayoutResult 
&layoutResult, Real32 scale = 1.f,
                 Vec2f offset = Vec2f(0,0), Color3f color = 
Color3f(1,1,1));

    /** Creates a new text geometry.  */
    GeometryPtr makeGeo(const TextLayoutResult &layoutResult, Real32 
scale = 1.f,
                        Vec2f offset = Vec2f(0,0), Color3f color = 
Color3f(1,1,1));

    /** Creates a new node with a text geometry.  */
    NodePtr makeNode(const TextLayoutResult &layoutResult, Real32 scale 
= 1.f,
                     Vec2f offset = Vec2f(0,0), Color3f color = 
Color3f(1,1,1));

The key changes were to:

- Refactor the geometry data format used to not use any indexing.  Dirk 
tells me that multi-indexing can perform poorly and it just makes it 
easier to implement...
- Added a method (addToGeom) that allows text to be added to an existing 
text geometry node
- Added color data to the geometry to allow for colored text

I updated the text param test program to use these additons.  You can 
see a screen shot of the application below.  Please note that all the 
text shown is contained in one single geometry core.

http://www.vrsource.org/~allenb/OpenSG_TextStuff.png

So, what do people think of this proposed change.  If it sounds good, I 
can pass the patch on to Dirk later today to commit.

-Allen