[osg-users] osgEarth Feature multiple draw

[Glenn Waldron]

Michele,

Yours is the most appropriate approach. There isn't a way to do what you
want with an existing higher-level construct.

I developed a similar capability in a client application; we call it a a
"track history". You are correct that localizing the geometry will
eliminate jitter; however, if the track is long enough, you will need to
break the track into multiple chunks and localize each chunk.

By the way, there is a forum/list specifically for osgEarth-related
questions: http://forum.osgearth.org

Good luck!


Glenn Waldron

On Wed, Apr 20, 2016 at 3:38 AM, Michele Onnis <michele.onnis at gmail.com>
wrote:

> Hi,
>
> I'm using the osgEarth library and I'm trying to draw Time Space Position
> Information datasets with a playback functionality. I want to draw the
> whole trajectory and then draw a subrange of the SAME trajectory, with a
> different style, for playback purposes: the playback subrange is
> "translated" over time to achieve the animation playback.
>
> In the first approach, I used two different node graphs based on
> osgEarth::Feature classes (Feature / Session / FeatureSource /
> FeatureModelGraph). I wanted to share the feature and specify two different
> draws of same feature (total range and partial range), but I could not find
> a way to do this. So, at every frame I add geometry to the playback feature
> and this action drops the framerate.
>
> To solve the problem, I've tried to switch to a "lower level"
> implementation based on osg::Geometry. In this case, I share the vertex
> array between the whole trajectory and the playback trajectory, then I
> specified two DrawArrays with different ranges for the different renders.
> The performance of this solution is perfect, but the geometry shows jitter
> problems related to the single precision of the GPU (geometry is specified
> in world coordinates).
>
> I know that in the second scenario I have to "localize" the geometry in a
> local origin to minimize the jitter, but I ask if there is a way to achieve
> the same results with the "higher level" approach (osgEarth::Feature
> classes), because I'd rather take advantage of all optimizations in this
> classes. So, how can I specify a single Feature and then specify multiple
> renders of the same Feature, with different ranges of the data and
> different styles?
>
> Thank you!
>
> Cheers,
> Michele
>
> ------------------
> Read this topic online here:
> http://forum.openscenegraph.org/viewtopic.php?p=66886#66886
>
>
>
>
>
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