In a graphics processing device, a plurality of processors write fragment shading results for order-dependent data to a buffer, according to the order in which the data is received. Fragment shading results for order-neutral data is written to the buffer one batch at a time. The order-dependent data comprises spatially overlapping data. Order-neutral data may not overlap. A scheduler controls the order of reception of one batch of data at a time by the processors. The order for receiving the order-dependent data may be determined. The plurality of processors may process the data in parallel. A writing order for writing results to a buffer from the processing in parallel, may be enforced. A portion of the processors may be instructed to wait before writing results to the buffer in a specified order. Processors signal when writing results to the buffer is complete.