Corrupt opengl context

OpenGL
1

Hello everyone,

searching for a bug, I came across some strange behavior of my app. Actually this behavior shows shortly before exiting (in some destructur in a class wrapping occulsion culling). I assume, that the opengl context is already destroyed BUT how do I know for sure.

Basically I am doing the following to check if there is a context:

if(wglGetCurrentContext()) {
…
if(glIsQuery(m_queryID)) {
glDeleteQueries(1, &m_query);
}
…
}

The programs crashes when calling glIsQuery (which is called several times during lifetime of the application, therefor there is no problem with taht extension so something like that).

I tried the following code for debugging purposes and it became even stranger:

if(wglGetCurrentContext()) {
char* version = (char*)glGetString(GL_VERSION);
GLenum error = glGetError();

// version is NULL now and error as well 0
}

So is there anyway, that wglGetCurrentContext returns a non-invalid handle but the context is not really valid anymore?

Did somebody had similar problems?

Thanks and regards,
Manuel

2

Try wglMakeCurrent to determine if RC and DC are still valid.

hth,
Shinta

3

Thanks Shinta. Reasonable idea. I tried this:

1       bool foundContext = false;
2       HGLRC rc = wglGetCurrentContext();
3       HDC   dc = wglGetCurrentDC();
4       if(rc != NULL && dc != NULL) {
5           foundContext = wglMakeCurrent(dc, rc);
6           if(!foundContext) {
7               DWORD error = GetLastError();
8           }
9       }

The result: an app crash (The program ‘…’ has exited with code 0 (0x0).) in line 5 - when trying to call wglMakeCurrent. No memory error nor something else promted by the debugger.

Any idea?

4

This topic was automatically closed 183 days after the last reply. New replies are no longer allowed.