Hi,
I have seen some discussion on this topic, but I have a specific OGRE based
benchmark that will hopefully allow me to narrow down ways to make my code more
efficient.
First, the benchmark uses Billboards while I am simply going for Quads,
although Billboards would be ideal.
In doing a bit of research, I came across the OGRE API and found this:
> Billboards have their geometry generated every frame depending on where the
> camera is. It is most beneficial for all billboards in a set to be
> identically sized since Ogre can take advantage of this and save some
> calculations - useful when you have sets of hundreds of billboards as is
> possible with special effects. You can deviate from this if you wish but be
> aware the extra overhead this brings and try to avoid it if you can.
Does this apply to OSG as well? I am not sure if I am reading the following
right in thinking the answer is "no" (from the beginners guide)
> Unfortunately, it is not clever enough to add the same drawable object to
> osg::Billboard with different positions, which could cause the node to work
> improperly.
In any case, OSG with Quads is performing slower than I had expected, although
I am rendering millions of Quads.
A snippet of what I am doing (the threshold logic is from the 3dc plugin):
Code:
geode=osg::ref_ptr<osg::Geode>(new osg::Geode());
osg::ref_ptr<osg::Geometry> geometry (new osg::Geometry());
osg::ref_ptr<osg::Vec3Array> vertices (new osg::Vec3Array(4));
osg::ref_ptr<osg::Vec4Array> colors (new osg::Vec4Array());
osg::ref_ptr<osg::Vec3Array> normals (new osg::Vec3Array());
for (int i=0; i<total_num_quads; i++) {
if (vertices->size()>=num_vertices_thresh)
{
geometry->setUseVertexBufferObjects(true);
geometry->setVertexArray(vertices.get());
geometry->setNormalArray(normals.get());
geometry->setColorArray(colors.get());
geometry->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);
geometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
geometry->addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertices->size()));
geode->addDrawable(geometry.get());
// allocate a new geometry
geometry = new osg::Geometry();
vertices = new osg::Vec3Array();
normals = new osg::Vec3Array();
colors = new osg::Vec4Array();
vertices->reserve(num_vertices_thresh);
normals->reserve(num_vertices_thresh);
colors->reserve(num_vertices_thresh);
}
}
// Create Quads
vertices->push_back (osg::Vec3 (point.x-0.5,point.y,point.z-0.5));
vertices->push_back (osg::Vec3 (point.x-0.5,point.y,point.z+0.5));
vertices->push_back (osg::Vec3 (point.x+0.5,point.y,point.z-0.5));
vertices->push_back (osg::Vec3 (point.x+0.5,point.y,point.z+0.5));
normals->push_back(osg::Vec3 (point.normal_x, point.normal_y,
point.normal_z));
normals->push_back(osg::Vec3 (point.normal_x, point.normal_y,
point.normal_z));
normals->push_back(osg::Vec3 (point.normal_x, point.normal_y,
point.normal_z));
normals->push_back(osg::Vec3 (point.normal_x, point.normal_y,
point.normal_z));
uint32_t red,green,blue,alpha;
red=point.r;
green=point.g;
blue=point.b;
alpha=point.a;
colors->push_back (osg::Vec4f ((float)red/255.0f, (float)green/255.0f,
(float)blue/255.0f,(float)alpha/255.0f));
colors->push_back (osg::Vec4f ((float)red/255.0f, (float)green/255.0f,
(float)blue/255.0f,(float)alpha/255.0f));
colors->push_back (osg::Vec4f ((float)red/255.0f, (float)green/255.0f,
(float)blue/255.0f,(float)alpha/255.0f));
colors->push_back (osg::Vec4f ((float)red/255.0f, (float)green/255.0f,
(float)blue/255.0f,(float)alpha/255.0f));
geometry->setUseVertexBufferObjects(true);
geometry->setVertexArray (vertices.get());
geometry->setNormalArray (normals.get());
geometry->setColorArray (colors.get());
geometry->setNormalBinding(osg::Geometry::BIND_PER_VERTEX);
geometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
geometry->addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertices->size()));
geode->addDrawable (geometry.get());
osg::StateSet* state = geometry->getOrCreateStateSet();
state->setMode( GL_LIGHTING,osg::StateAttribute::OFF);
...
Thank you!
Cheers,
Phil[/code][/url]
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=52959#52959
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