Martin Großer wrote:
Hello all,
maybe the subject isn't very significant, but I would like explane my
idea. I would like visualize a vector field. I have a gird and every
grid cell have a velocity value in x and in y. Also I have the array _x
and _y. Now I create a geometry and a vertex array:
osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array;
[...]
vertices->push_back( osg::Vec3(0,0,0.0) );
vertices->push_back( osg::Vec3(_x[i], _y[j], 0.0) );
Now I change the values of _x and _y during the runtime, but the
geometry isn't changing. I would like pass a pointer to the osg::Vec3
and use the function "dirtyDisplayList".
vertices->push_back( osg::Vec3(&_x[i], &_y[j], 0.0) );
[...]
geom->dirtyDisplayList();
Hi, Martin,
If I understand you correctly, you've got a couple of issues.
First, make sure you tell OSG that the geometry's data will be changing:
geom->setDataVariance(osg::Object::DYNAMIC);
Second, you can avoid having to call dirtyDisplayList() every frame by
simply disabling display lists:
geom->setUseDisplayList(false);
Finally, do you call clear() on the vertex array before adding the new
vertex values? If not, you're just adding values to the end of the
array which will never be drawn. Try this instead:
osg::Vec3Array::iterator itr;
itr = vertices.begin();
int i = 0;
while (itr != vertices.end())
{
itr->set(&_x[i], &_y[i], 0.0);
itr++;
i++;
}
I'm assuming the number of vectors is fixed, of course. If that can
change, you'll have to alter the code a bit.
Hope this helps...
--"J"
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