// Problem: Calling Screenshot(2, 2) generates 4 pics, 3 of which contain my image but 1 which doesn't
// (and combined they still don't contain all of it) Not sure what's off...
// Following isntructions here:
// http://www.opengl.org/resources/code/samples/sig99/advanced99/notes/node30.html
void TestGLCanvas::Screenshot(int width_mult, int height_mult)
{
    int win_width, win_height;
    GetClientSize(&win_width, &win_height);

    glMatrixMode(GL_PROJECTION);
    
    for(int y = 0; y < height_mult; ++y) {
	for(int x = 0; x < width_mult; ++x) {
	    wxLogDebug(wxString() << width_mult << _T(" ") << height_mult << _T(" ") << x << _T(" ") << y);
	    float sceneWidth = win_width * width_mult;
	    float sceneHeight = win_height * height_mult;

	    float xTileWidth = sceneWidth / width_mult;
	    float yTileWidth = sceneHeight / height_mult;

	    float xOffset = (-2 * x * xTileWidth / sceneWidth) + (1 - 1 / width_mult);
	    float yOffset = (-2 * y * yTileWidth / sceneHeight) + (1 - 1 / height_mult);

	    Render(width_mult, height_mult, xOffset, yOffset);

	    Screenshot(wxString(_T("shot")) << y << x << _T(".jpg"));
	}
    }
}