OpenGL (Windows) not drawing to screen - windows

Question

I'm trying to start experimenting with OpenGL and Windows GUI stuff. I'm running Windows 7 on my dev box and running Visual Studio 2013. When I run the below code, I don't receive any errors and all the of window information seems correct but nothing is drawn to the screen from OpenGL.
For a first program I was looking to put an overlay on top of Notepad, then draw a line/plus sign somewhere in the screen.
First I create a window:
myWindow = CreateWindowEx(
WS_EX_TRANSPARENT | WS_EX_TOPMOST | WS_EX_LAYERED,
WINDOW_NAME,
WINDOW_NAME,
WS_POPUP | WS_VISIBLE | WS_MAXIMIZE,
g_NotepadCoords.left,
g_NotepadCoords.top,
g_width,
g_height,
NULL, NULL, g_me, NULL);
The globals and coordinates for the window are calculated using FindWindowA and GetClientRect. Both of these function calls succeed and return reasonable values. After CreateWindowEx, I use the following function calls to set properties and check support, etc:
SetLayeredWindowAttributes(myWindow, RGB(0, 0, 0), 255, LWA_ALPHA | LWA_COLORKEY);
if (S_OK != DwmIsCompositionEnabled(&bIsEnabled)){...}
Right now HandleWindowMessage has WM_CREATE, WM_CLOSE, WM_DESTROY and WM_PAINT enabled. SetupOpenGL is called in WM_CREATE, and the drawing happens in WM_PAINT.
WM_CREATE and WM_PAINT:
case WM_CREATE:
{
printf("WM_CREATE\n");
g_Hdc = GetDC(hWnd);
SetupGL();
return 0;
}
break;
case WM_PAINT:
{
GLenum err;
const GLubyte *errString;
RGB colorToDraw = { 0 };
drawPlus(g_.middleX, g_.middleY, 12, 12, 4, &colorToDraw);
err = glGetError();
errString = gluErrorString(err);
printf("ERROR DRAWING? %s\n", errString);
}
break;
As far as I can tell I set up OpenGL correctly; no errors are printed:
void SetupOpenGL()
{
__try{
PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR),
1,
PFD_DRAW_TO_WINDOW | // Format Must Support Window, OPENGL, Composition
PFD_SUPPORT_OPENGL |
PFD_SUPPORT_COMPOSITION |
PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA, // RGBA
32,
0, 0, 0, 0, 0, 0,
8, // alpha
0, 0, 0, 0, 0, 0, 0,
8, // stencil Buffer
0,
PFD_MAIN_PLANE, // Main Drawing Layer
0, 0, 0, 0
};
PixelFormat = ChoosePixelFormat(g_Hdc, &pfd);
if (0 == PixelFormat)
{
printf("ChoosePixelFormat failed %d\n", GetLastError());
__leave;
}
if (!SetPixelFormat(g_Hdc, PixelFormat, &pfd))
{
printf("SetPixelFormat failed %d\n", GetLastError());
__leave;
}
if (!DescribePixelFormat(g_Hdc, PixelFormat, sizeof(PIXELFORMATDESCRIPTOR), &pfd))
{
printf("DescribePixelFormat failed %d\n", GetLastError());
__leave;
}
g_MainHGLRC = wglCreateContext(g_Hdc);
if (!g_MainHGLRC)
{
printf("wglCreateContext failed %d\n", GetLastError());
__leave;
}
if (!wglMakeCurrent(g_Hdc, g_MainHGLRC))
{
printf("wglMakeCurrent failed %d\n", GetLastError());
__leave;
}
glMatrixMode(GL_PROJECTION);
glClearColor(0.f, 0.f, 0.f, 0.f);
}
__finally{}
}
And then drawPlus is super simple:
void drawPlus(float x, float y, float width, float height, float lineWidth, RGB* RGB)
{
printf("drawPlus(%f,%f,%f,%f,%f,[%d,%d,%d])", x, y, width, height, lineWidth, RGB->red, RGB->green, RGB->blue);
glLineWidth(lineWidth);
glBegin(GL_LINES);
glColor4f(RGB->red, RGB->green, RGB->blue, 1);
glVertex2f(x, y + height/2);
glVertex2f(x, y - height/2);
glVertex2f(x + width/2, y);
glVertex2f(x - width/2, y);
glEnd();
}
When I run it, I don't receive any errors, I can see the executable creating another window and I've confirmed that drawPlus is getting called correctly and with good parameters. However, there's nothing actually drawn to the screen so I'm not sure what I'm missing. I just ran a quick check on the coordinates and for the Notepad windows elements I got:
top: 86
bottom: 916
left: 170
right: 609
And then for where to draw the plus I got
x = 219
y = 412
Which both seem reasonable so it's not my windows being mismatched or etc.