[osg-users] Updating VBO's during runtime

[Daniel Emminizer, Code 5773]

Hi Brad,

Check to make sure your Geometry has setDataVariance(osg::Object::DYNAMIC).  That solved the problem for most of our similar cases.

- Dan


From: osg-users [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Brad Colbert
Sent: Friday, June 01, 2018 10:20 AM
To: osg-users at lists.openscenegraph.org
Subject: [osg-users] Updating VBO's during runtime

I'm updating my vertices at runtime.  I've found a few posts that discuss this:

(a couple are:)
http://forum.openscenegraph.org/viewtopic.php?t=14826
http://forum.openscenegraph.org/viewtopic.php?t=15782

Let me first mention that I've compiled OSG with GL3 support, so no display lists.  That said, I'm still calling:

  pointsGeom->setUseDisplayList(false);
  pointsGeom->setUseVertexBufferObjects(true);

Here is a snippet of my call to update the vertices (v_ = vertices, c_ = colors, n_ = normals, da_ = DrawArrays, g_ = Geometry):

    for (int i = 0; i < numVertices; i++) {
      // Verticies
      v_.at(i)[0] = 500.f * (0.0f + (3.0f * float(rand() % 1000) / 1000.f) - 1.5f);
      v_.at(i)[1] = 500.f * (0.0f + (4.0f * float(rand() % 1000) / 1000.f) - 2.f);
      v_.at(i)[2] = 500.f * (1.5f + (0.1f * float(rand() % 1000) / 1000.f) - 0.05f);

      // Colors
      c_.at(i)[0] = 1.f;
      c_.at(i)[1] = 1.f;
      c_.at(i)[2] = 1.f;
      c_.at(i)[3] = 1.f;

      // Normals
      n_.at(i)[0] = 0.f;
      n_.at(i)[1] = 1.f;
      n_.at(i)[2] = 0.f;
    }

    v_.dirty();
    c_.dirty();
    n_.dirty();

    da_.setCount(numVertices);
    da_.dirty();

    // *** The dirty() calls above are supposed to tell OSG to update the VBO's.  For
    // some reason this isn't happening.  We are going to force it here.  Not sure of the
    // performance implications but hopefully this is temporary.
    g_.setVertexArray(&v_);
    g_.setColorArray(&c_);
    g_.setNormalArray(&n_);

    g_.dirtyBound();

The update just doesn't happen unless I call the setVertexArray, setColorArray, setNormalArray methods which doesn't match what the previous posts about this topic.

Is this because of GL3 or something else?

Thanks,
Brad
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