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
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