CODEWITHSUNDEEP
c++openglinteropsegmentation-faultopencl
Yuuta
Yuuta

Reputation: 414

glXGetCurrentDisplay() Segmentation Fault (Linux)

I'm working with OpenCL/OpenGL interop and have been able to get it successfully working on OSX:

props[0] = CL_CONTEXT_PROPERTY_USE_CGL_SHAREGROUP_APPLE;
props[1] = (cl_context_properties) CGLGetShareGroup( CGLGetCurrentContext() );

However, when using the X correspondent: 

props[0] = CL_GL_CONTEXT_KHR;
props[1] = (cl_context_properties) glXGetCurrentContext();
props[2] = CL_GLX_DISPLAY_KHR;
props[3] = (cl_context_properties) glXGetCurrentDisplay();
props[4] = CL_CONTEXT_PLATFORM;
props[5] = (cl_context_properties) pID;

OpenGL init code:

glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

screenWidth  = glutGet(GLUT_SCREEN_WIDTH);
screenHeight = glutGet(GLUT_SCREEN_HEIGHT);

glutInitWindowPosition( (screenWidth - width)/2 , (screenHeight - height)/2 );
glutInitWindowSize(width, height);
glutCreateWindow(appName.c_str());

glClearColor (0.0, 0.0, 0.0, 0.0);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);

glEnable(GL_COLOR_MATERIAL);

glShadeModel(GL_SMOOTH);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

glEnable (GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glutDisplayFunc(render_s);
glutIdleFunc(render_s);
glutReshapeFunc(resize_s);
glutKeyboardFunc(keyPress_s);
glutKeyboardUpFunc(keyRelease_s);
glutMouseFunc(mousePress_s);
glutMotionFunc(mouseDrag_s);
glutPassiveMotionFunc(mouseMove_s);

The init code is called before getting the context.

glXGetCurrentContext() didn't segfault, but glXGetCurrentDisplay() did.

Excluding the interop, why would glXGetCurrentDisplay() seg fault even after calling glutInit()

P.S. Is there a way to explicitly choose the platform/device under OpenGL?

Upvotes: 1

Views: 865

Answers (2)

McLeary
McLeary

Reputation: 1271

I just face the same problem. What I found is that you need to initialize the glx extensions. I'm using glew for this one so I need to call glewInit() after the context was created in order to glXGetCurrentDisplay() to work properly.

Check your headers. If you are including GL/glxew.h you need to initialize the function pointers in some way. If you include GL/glx.hit should work fine.

Upvotes: 1

datenwolf
datenwolf

Reputation: 162164

fault even after calling glutInit()

glutInit doesn't create an OpenGL context, so glXGetCurrentDisplay will fail. You need to call glutCreateWindow to actually create a context.

Upvotes: 5

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