Thanks for the suggestions, Robert! I was just investigating such
possibilities, shows I'm on the right track...
/Andreas
On 2017-09-22 12:13, Robert Osfield wrote:
Hi Andreas.
On 22 September 2017 at 09:40, Andreas Ekstrand
<andreas.ekstr...@remograph.com
<mailto:andreas.ekstr...@remograph.com>> wrote:
I'm using osgText to show vertex numbers. Often enough it's only
0,1,2 for triangles but it can be several hundred thousands of them.
It's never been optimal, I know - and I guess this is the time to
do something about it, I will look into an alternative way without
osgText. Any suggestions are welcome!
On the OSG side I steadily shifting osgText to using shaders for
effects and simplifying the CPU side. Not all the way there yet but
that's the direction I'm going with it. Simplifying the CPU side will
mean less custom data manipulation that is different frrom
osg::Geometry that just pushes arrays and primitives to GL. With
these evolution of osgText the overhead for creating new text should
be lower.
However, osgText it will always be a general purpose text
implementation rather than a highly tuned for a specific purpose. In
your case it might be simpler to do some specifically your task. If
you have just 0..9 characters and a limited number of characters you
start thinking about doing far more on the GPU.
For instance you could use a single textured quad for each label,
passing in the characters to render via a uniform array or packed
uniforms and have a shader work out what texture coordinates into the
glyph texture atlas to use to render each character, then in the
fragment shader get the appropriate samples for each character. I
have used this approach on client project to make a very lightweight
system for rendering labels, it was a closed source project so not
something I can share the implementation, but it does at least show it
works.
Another approach you could take is just create your own osg::Geometry
and reuse the osgText::Font/osgText::GlyhTexture. In the end basic
rendering of text is just texture quads, osgText can be used to
provide the texture atlas you need so most of the awkward work is done
for you already.
Robert.
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