Archives Discussions

sajis997 · ‎05-09-2013

Hi forum,

For OpenCL - OpenGL interoperability, i believe you need to create the GL context first before initializing the OpenCL context. And i am doing the same , but i failed the create the OpenCL context. I think i am missing something in the process and i need your help here.

this OpenCL context creation is encapsulated into a class structure as an attempt to extend the scene graph system with OpenCL support. Here it goes:

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

osgOpenCLContext::osgOpenCLContext(): m_clContext(NULL),

m_clPlatform(NULL),

m_clDevice(NULL),

m_clCommandQueue(NULL)

{

}

osgOpenCLContext::~osgOpenCLContext()

{

if(m_clCommandQueue) clReleaseCommandQueue(m_clCommandQueue);

if(m_clContext) clReleaseContext(m_clContext);

}

bool osgOpenCLContext::setupOsgOpenCLAndViewer(osgViewer::ViewerBase &viewer,

int ctxID /*= -1 */)

{

// You must use single threaded version since osgCompute currently

// does only support single threaded applications.

viewer.setThreadingModel( osgViewer::ViewerBase::SingleThreaded );

// Does create a single OpenGL context

// which is not released at the end of a frame to secure

// CUDA launches everywhere

viewer.setReleaseContextAtEndOfFrameHint(false);

// Create the current OpenGL context and make it current

if( !viewer.isRealized() )

viewer.realize();

osgViewer::ViewerBase::Contexts ctxs;

viewer.getContexts( ctxs, true );

if( ctxs.empty() )

{

osg::notify(osg::FATAL)<< __FUNCTION__ << ": no valid OpenGL context is found."<<std::endl;

return false;

}

osg::GraphicsContext* ctx = NULL;

#ifdef WIN32

osgViewer::GraphicsHandleWin32 *windowsContext = NULL;

#else

osgViewer::GraphicsHandleX11 *linuxContext = NULL;

#endif

if( ctxID != -1 )

{ // Find context with ctxID and make it current.

for( unsigned int c=0; c<ctxs.size(); ++c )

{

if( ctxs->getState()->getContextID() == ctxID )

{

ctx = ctxs;

}

else

{

ctx = ctxs.front();

}

if( NULL == ctx )

{

osg::notify(osg::FATAL)<< __FUNCTION__ << ": cannot find valid OpenGL context."<<std::endl;

return false;

}

//platform dependent casting

#ifdef WIN32

windowsContext = dynamic_cast<osgViewer::GraphicsHandleWin32*>(ctx);

if(NULL == windowsContext)

{

osg::notify(osg::FATAL) << "Win32 Graphics Context Casting is unsuccessful" << std::endl;

return false;

}

else

osg::notify(osg::INFO) << "Win32 Graphics Context Casting is successful" << std::endl;

#else

linuxContext = dynamic_cast<osgViewer::GraphicsHandleX11*>(ctx);

if(NULL == linuxContext)

{

osg::notify(osg::FATAL) << "X11 Graphics Context Casting is unsuccessful" << std::endl;

return false;

}

else

osg::notify(osg::INFO) << "X11 Graphics Context Casting is successful" << std::endl;

#endif

cl_uint numPlatforms;

cl_platform_id *platformIDs;

cl_int errNum;

//first query the total number of platforms

errNum = clGetPlatformIDs(0,NULL,&numPlatforms);

if(errNum != CL_SUCCESS || numPlatforms <= 0)

{

osg::notify(osg::FATAL) << "Failed to find any OpenCL platform" << std::endl;

return false;

}

//next, allocate memory for the installed platforms, and query

//to get the list

platformIDs = (cl_platform_id *)alloca(sizeof(cl_platform_id) * numPlatforms);

errNum = clGetPlatformIDs(numPlatforms,platformIDs,NULL);

if(errNum != CL_SUCCESS)

{

osg::notify(osg::FATAL) << "Failed to find any OpenCL platform" << std::endl;

return false;

}

//now choose the very first platform

m_clPlatform = platformIDs[0];

char cBuffer[1024];

//get the platform information from the selected platform

errNum = clGetPlatformInfo(m_clPlatform,CL_PLATFORM_NAME,sizeof(cBuffer),cBuffer,NULL);

if(errNum == CL_SUCCESS)

{

osg::notify(osg::INFO) << "OpenCL platform name: " << cBuffer << std::endl;

}

//by now the graphics context is found

//and the platform id is also found

cl_context_properties contextProperties[] =

{

#ifdef WIN32

CL_GL_CONTEXT_KHR, (cl_context_properties) windowsContext->getWGLContext(),

CL_WGL_HDC_KHR, (cl_context_properties) windowsContext->getHDC(),

#else

CL_GL_CONTEXT_KHR, (cl_context_properties) linuxContext->getContext(),

CL_GLX_DISPLAY_KHR, (intptr_t) linuxContext->getDisplay(),

#endif

CL_CONTEXT_PLATFORM, (cl_context_properties) m_clPlatform,

0

};

//create context with the GPU device only

m_clContext = clCreateContextFromType(contextProperties,CL_DEVICE_TYPE_GPU,NULL,NULL,&errNum);

if(errNum != CL_SUCCESS)

{

std::cout << "Could not create GPU context." << std::endl;

osg::notify(osg::FATAL) << "Could not create GPU context." << std::endl;

return false;

}

else

osg::notify(osg::INFO) << "Context Creation for the GPU is Successful" << std::endl;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

The OpenGL context is created inside the main function as follows:

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

int main(int argc, char *argv[])

{

osg::setNotifyLevel( osg::INFO );

//////////////////

// SETUP VIEWER //

//////////////////

osgViewer::Viewer viewer;

viewer.addEventHandler(new osgViewer::StatsHandler);

//viewer.addEventHandler(new osgCuda::StatsHandler);

viewer.addEventHandler(new osgViewer::HelpHandler);

viewer.setUpViewInWindow( 50, 50, 640, 480);

viewer.getCamera()->setClearColor( osg::Vec4(0.15, 0.15, 0.15, 1.0) );

//declare an opencl context

osgOpenCL::osgOpenCLContext clContext;

clContext.setupOsgOpenCLAndViewer(viewer);

return viewer.run();

}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

I also print the diagnostics as follows:

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

sajjad@sajjad-G74Sx:~/Downloads/OpenSceneGraph/osgCompute/osgCompute$ ./bin/osgOpenCLTexDemo