Hello Keyan,
On 11/07/2011 08:08 AM, Keyan wrote:
> in my application, I would like to visualize the trajectory of an object. For
> this purpose, I store the coordinates at given intervals. The trajectory may
> be of limited length, e.g. the last 100 steps, or unlimited.
>
> I also want to choose the color for the trajectory segments, having a higher
> transparency for points further back in the past.
>
> What is the best way to visualize such a trajectory. I only found the
> drawLines function and the OSG::Lines objects.
create a OSG::Geometry that contains one or more GL_LINE_STRIPs:
OSG::GeometryRefPtr geo = OSG::Geometry::create();
OSG::GeoUInt8PropertyRefPtr types = OSG::GeoUInt8Property::create();
types->push_back(GL_LINE_STRIP);
OSG::GeoPnt3fPropertyRefPtr pos = OSG::GeoPnt3fProperty::create();
pos->push_back(OSG::Pnt3f(0.f, 0.f, 0.f));
// etc. for history of object positions
OSG::Color4fPropertyRefPtr color = OSG::GeoColor4fProperty::create();
// add colors
OSG::GeoUInt32PropertyRefPtr lengths = OSG::GeoUInt32Property::create();
lengths->push_back( /* lenght of first strip */);
lengths->push_back( /* lenght of second strip, if any */);
// etc.
geo->setTypes (types);
geo->setLengths(lengths);
geo->setProperty(pos, OSG::Geometry::PositionsIndex);
geo->setProperty(color, OSG::Geometry::ColorsIndex);
// disable display list generation for this geometry
geo->setDlistCache(false);
If the geometry changes frequently generating display lists is going to
hurt performance, so depending on how often you modify the trajectories
you probably want to turn it off.
For the limited length lines where the positions basically form a
ring-buffer of the 100 last positions, you may want to use an index so
that you only have to overwrite the oldest position and color and adjust
the index - instead of rewriting all colors/positions.
Cheers,
Carsten
------------------------------------------------------------------------------
RSA(R) Conference 2012
Save $700 by Nov 18
Register now
http://p.sf.net/sfu/rsa-sfdev2dev1
_______________________________________________
Opensg-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/opensg-users
