So, there's a convention to make the pixel the color of the edge that's on the upper/left side right? What if there are three or more triangles that all share the same point at the center of the pixel? I'm thinking of a bunch of triangles radiating from the center of the pixel.

@jared711, if they have different z values, which ever is closest to the camera view would take the pixel I guess. If they have the same z values, I guess it depends on the rasterizer implementation?