1. A computer-implemented method of interpolating attributes used in computer graphics, the method comprising: accessing, using a graphics processing unit (GPU) executing a graphics pipeline, vertex data for a graphics primitive having an area associated therewith, the vertex data comprising homogeneous coordinates for each vertex of the primitive, the homogeneous coordinates comprising a first coordinate x, a second coordinate y, and a third coordinate w; accessing, using said GPU, a first plurality of barycentric coordinates for a first pixel associated with the primitive; using a first plurality of ratios, determining, in said graphics pipeline, a first plurality of normalized perspective-correct barycentric coordinates that are normalized by the area of the primitive, the first plurality of ratios comprising a respective value of the barycentric coordinates divided by a respective value of the third coordinate; using the first plurality of normalized perspective-correct barycentric coordinates, determining, in said graphics pipeline, an interpolated value of an attribute for the first pixel and rendering the first pixel according to the interpolated value.