Hi, Robert.
I've managed to render to 3D texture and I wrote a simple demo to show
how to use it. Everyone with Nvidia Geforce 8800 Series can run this
program.
But I found it has very slow performance. In this example, with
256*256*256 3D texture, only 8 fps was show on my 8800GTS 320M. I see
the StatsHandler's value here:
FPS 8.56
Cull 38.24
Draw 70.70
GPU 82.50
It wastes a lot of time do Culling and Drawing. Is there any way to
reduce the cull time and draw time? Thanks!
#include <osg/Node>
#include <osg/Geometry>
#include <osg/Drawable>
#include <osg/ShapeDrawable>
#include <osgGA/TrackballManipulator>
#include <osgViewer/Viewer>
#include <osg/Texture3D>
#include <osgViewer/ViewerEventHandlers>
#include <osgDB/ReadFile>
#include <osgDB/WriteFile>
#include <osgViewer/ViewerEventHandlers>
#include <osgUtil/Optimizer>
#include <osg/MatrixTransform>
using namespace osg;
using namespace osgViewer;
int _tmain(int argc, _TCHAR* argv[])
{
ref_ptr<Group> root= new Group;
ref_ptr<Image> img=new Image;
img->allocateImage(256,256,256, GL_RGBA, GL_UNSIGNED_BYTE);
ref_ptr<Texture3D> txt3D=new Texture3D;
txt3D->setFilter(Texture3D::MIN_FILTER, Texture3D::LINEAR);
txt3D->setFilter(Texture3D::MAG_FILTER, Texture3D::LINEAR);
txt3D->setImage(img.get());
txt3D->setTextureSize(256,256,256);
txt3D->setInternalFormat(GL_RGBA);
const unsigned char TEXTURE_3D=0;
for(int z=0;z<256;z++)
{
ref_ptr<Camera> camera=new Camera;
camera->setClearColor(Vec4(0,0,0,0));
camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
camera->setReferenceFrame(Transform::ABSOLUTE_RF);
camera->setRenderOrder(osg::Camera::PRE_RENDER);
camera->setRenderTargetImplementation(Camera::FRAME_BUFFER_OBJECT);
camera->attach(Camera::COLOR_BUFFER, txt3D.get(), 0, z, false);
camera->setViewport(0,0, 256,256);
ref_ptr<Geode> box=new Geode();
box->addDrawable(new ShapeDrawable(new
Sphere(Vec3(1/256.0*z,0,0), 1)));
camera->addChild(box.get());
root->addChild(camera.get());
}
ref_ptr<Geode> geode=new Geode;
ref_ptr<Geometry> geo=new Geometry;
geode->addDrawable(geo.get());
ref_ptr<Vec3Array> vertex=new Vec3Array;
ref_ptr<Vec3Array> txtcoord=new Vec3Array;
for(int z=0;z<256;z++)
{
vertex->push_back(Vec3(0,0,z/256.0));
vertex->push_back(Vec3(1,0,z/256.0));
vertex->push_back(Vec3(1,1,z/256.0));
vertex->push_back(Vec3(0,1,z/256.0));
txtcoord->push_back(Vec3(0,0,z/256.0));
txtcoord->push_back(Vec3(1,0,z/256.0));
txtcoord->push_back(Vec3(1,1,z/256.0));
txtcoord->push_back(Vec3(0,1,z/256.0));
}
geo->setVertexArray(vertex.get());
geo->setTexCoordArray(TEXTURE_3D, txtcoord.get());
geo->addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::QUADS,0,vertex->size()));
geo->getOrCreateStateSet()->setTextureAttributeAndModes(TEXTURE_3D,
txt3D.get(),osg::StateAttribute::ON);
root->addChild(geode.get());
root->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF |
osg::StateAttribute::OVERRIDE);
osgUtil::Optimizer optimzer;
optimzer.optimize(root.get());
ref_ptr<Viewer> viewer=new Viewer;
osg::ref_ptr<osg::GraphicsContext::Traits> traits = new
osg::GraphicsContext::Traits;
traits->x = 100;
traits->y = 100;
traits->width = 1024;
traits->height = 768;
traits->windowDecoration = true;
traits->doubleBuffer = true;
traits->sharedContext = 0;
ref_ptr<GraphicsContext> gc =
osg::GraphicsContext::createGraphicsContext(traits.get());
viewer->getCamera()->setGraphicsContext(gc.get());
viewer->getCamera()->setViewport(0,0, 1024,768);
viewer->setSceneData(root.get());
viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
viewer->addEventHandler(new osgViewer::StatsHandler);
viewer->run();
}
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