1. A method for compressing graphics data comprising a plurality of z-planes and samples, the method comprising: selecting z-planes from the plurality of z-planes, wherein the selected z-planes are predictor planes; determining a residual for each sample not covered by one of the predictor z-planes, wherein a sample is covered by one of the predictor z-planes when the predictor plane correctly defines a z-value for the sample, and wherein a residual comprises a value that is a difference between a predicted z-value provided by one of the predictor z-planes and an actual z-value for the sample; and storing the predictor planes and the residuals in a z-buffer.