Results 1 to 4 of 4

Thread: Multi-threading and OpenGL context problem on Win32

  1. #1
    Junior Member Newbie
    Join Date
    Dec 2013

    Multi-threading and OpenGL context problem on Win32

    I'm just trying to write a simple program with some OpenGL rendering that works on Linux and Windows and I test it with nVidia and AMD video cards. It have 2 modes of operation:

    1) Single-thread. Window events polling and OpenGL rendering is in main thread, no other threads are created. Works as it should on both Linux and under Windows with any video card.
    2) Multi-threaded. Window events polling is in main thread, OpenGL context creation and rendering is in secondary thread. Works on Linux with any card and under Windows with Nvidia but not with AMD.

    Multi-threaded mode under Windows with AMD card fails in secondary thread on first call to wglMakeCurrent. My code to create context:

    Code :
    Win32Context::Win32Context(Window &rWindow):
    	m_pWindow(&rWindow) {
    	HWND hWindow = (HWND)m_pWindow->getNative();
    	m_hDC = GetDC(hWindow);
    	m_hContext = NULL;
    	// context is created without errors here:
    	create(GLContext::GL_COMPATIBILITY, NULL);
    	if (!WGL::_loaded) {
    		// To load a WGL extensions we need a context set as current.
    		// Fails on this call (with memory access error in atiDrvPresentBuffer):
    		wglMakeCurrent(m_hDC, m_hContext);
    		int nResult = WGL::LoadFunctions(m_hDC); // load WGL extensions...
    		assert(nResult == WGL::_LOAD_SUCCEEDED);
    		wglMakeCurrent(NULL, NULL);
    bool Win32Context::create(GLContext::Profile nProfile, const Win32Context *pShareContext) {
    	if (m_hContext != NULL) {
    		m_hContext = NULL;
    	if (nProfile == GLContext::GL_COMPATIBILITY) {
    	    m_hContext = wglCreateContext(m_hDC);
    	    m_nProfile = GLContext::GL_COMPATIBILITY;
    	    if (m_hContext && pShareContext) {
    	    	wglShareLists(pShareContext->m_hContext, m_hContext);
    	else {
    		if (!WGL::_ARB_create_context_profile) {
    			return false;
    		int nGLVerMaj, nGLVerMin;
    		switch (nProfile) {
    		case GLContext::GL_CORE_3_3:
    			nGLVerMaj = 3; nGLVerMin = 3;
    			return false;
    		int vContextAttrib[] = {
    #if defined(_DEBUG) || defined(_GL_DEBUG)
    												| WGL_CONTEXT_DEBUG_BIT_ARB
    		vContextAttrib[1] = nGLVerMaj;
    		vContextAttrib[3] = nGLVerMin;
    		m_hContext = wglCreateContextAttribsARB(m_hDC,
    				pShareContext ? pShareContext->m_hContext : NULL,
    		m_nProfile = nProfile;
        return m_hContext != NULL;

    So, does anyone has same problem? Is it just a bug in driver or I doing something wrong?

    Sorry for my bad English. Leon.

  2. #2
    Senior Member OpenGL Pro
    Join Date
    Jan 2012
    Make sure you have the latest AMD driver - their drivers are not as stable as nVidia. Also try using
    Code :
    int vContextAttrib[] = {0};

    that is not options - when creating the device context

  3. #3
    Junior Member Newbie
    Join Date
    Dec 2013
    tonyo_au, thanks for reply.

    I already fixed this, seems like GL context must be created in same thread that created a window, and then I can use this context in other threads. Also, rendering threads must have a large stack, the OpenGL driver eats stack a lot.

    Sorry for my bad English. Leon.

  4. #4
    Senior Member OpenGL Pro Aleksandar's Avatar
    Join Date
    Jul 2009
    Besides, don't use wglShareLists(). GL3+ should use shared groups.

Similar Threads

  1. Multi-threading in OpenGL ES from Cocos2D iOS App
    By patrick99e99 in forum OpenGL: Basic Coding
    Replies: 13
    Last Post: 10-05-2016, 09:23 PM
  2. Shared context and multi-threading
    By slimshader in forum OpenGL: Advanced Coding
    Replies: 4
    Last Post: 11-08-2012, 01:44 PM
  3. multi threading in openGL
    By jayaprakash in forum OpenGL: Windows
    Replies: 1
    Last Post: 01-29-2009, 07:19 AM
  4. render context with multi threading
    By Sektor_3700 in forum OpenGL: Basic Coding
    Replies: 6
    Last Post: 10-24-2005, 03:31 PM
  5. OpenGL multi threading under Windows and C
    By hanner in forum OpenGL: Advanced Coding
    Replies: 6
    Last Post: 07-01-2003, 06:09 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Proudly hosted by Digital Ocean