0 Replies Latest reply on Sep 24, 2015 2:04 PM by CH77

    Intel HD 4600 - OpenGL issue when setting MSAA

    CH77

      Hello,

       

       

      we have an ActiveX control, coded in VS6 C++.

      It uses OpenGL to draw lines in simple ways, nothing with textures etc.

       

       

      It behaves as expected for years now on many different graphics adapters.

      Also on Intel HD 4000 and lower.

       

       

      But from HD 4600 on, we get a crash in ig75icd32.dll.

       

       

      We found out that the crash only occurs when a mousemove or mousewheel event happens while the control gets recreated (RecreateControlWindow();).

       

       

      We further found out that if we avoid the messages in the code, the crash does not happen.

      Easy so far.

       

       

      But we must let the messages come in after the control is recreated.

      Also easy, but when we *think* the control is available again, it isn't.

      After RecreateControlWindow();, the control seems to be not available, and an incoming message leads to the crash.

       

       

      So we are looking for a method to really know when the OpenGL context is fully created.

      Then we can permit the messages again with no crash.

       

       

      We still wonder why this problem only occurs on the newer HD Graphics, not on the older ones.

      A driver bug?

       

       

      Ideas?

      Hints?

       

       

      Thank you.