OpenGL GL_POLYGON_SMOOTH 2D Antialiasing creating tris out of quads

Question

UPDATE:

I have located it to when I install NVIDIA Control Panel, if I uninstall it it works properly.

When you rotate a quad in OpenGL the edges become jagged.

If I call glEnable(GL_POLYGON_SMOOTH) the edges become smooth, but OpenGL then draws a white diagonal line through all my images as if it's creating trisout of my quads.

This is how it looks:

Is there a way to disable that line, or can I get antialiasing in another easy way? I tried GL_MULTISAMPLE but nothing happened.

In my code I have also:

glShadeModel(GL_SMOOTH);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

glDisable(GL_DEPTH_TEST);

glEnable(GL_BLEND);

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

Answer 1

Ok, I'll write this up as an answer, let me know if it works after trying it out.

GL_TRIANGLE_FAN: If the application specifies a sequence of vertices v, OpenGL renders a triangle using v 0, v 1, and v 2; another triangle using v 0, v 2, and v 3; another triangle using v 0, v 3, and v 4; and so on. If the application specifies n vertices, OpenGL renders n–2 connected triangles.

So to draw a unit quad centered around the origin,

glBegin(GL_TRIANGLE_FAN);

glTexCoord2f(0f, 0f);
glVertex3f(-halfWidth, -halfHeight, 0f);

glTexCoord2f(0f, 1f);
glVertex3f(-halfWidth, halfHeight, 0f);

glTexCoord2f(1f, 1f);
glVertex3f(halfWidth, halfHeight, 0f);

glTexCoord2f(1f, 0f);
glVertex3f(halfWidth, -halfHeight, 0f);

glEnd();

Now you can put the same transformations around this that you used around your quad! Hope that helps!