Interpolation/wrapping artifacts with default texture settings.

If you apply a texture to a quad with default settings, the texture wraps at the edges causing artifacts.

In the attached example, the texture is a black square with one white corner (texture_wrap_source.png). When applied to a quad, lines can be seen opposite the white corner in both x & y.

Using a color example, it is more difficult to see, but a blue & yellow test shows pixels on the opposite edge with a greyish color rather than either yellow or blue, which implies that the edges of the texture are being interpolated across the boundry rather than wrapping.