1. A computer-implemented method for distributing primitives to multiple rasterizers, the method comprising: receiving multiple streams of primitives from multiple source processing cores that are within a first processing cluster included in a plurality of processing clusters; computing a destination mask indicating which processing clusters should receive each one of the primitives; transmitting a first primitive to a local buffer that is within the first processing cluster when the destination mask indicates that the first primitive output by a first source processing core that is included within the first processing cluster should be sent to the first processing cluster; transmitting a second primitive to a second processing cluster included in the plurality of processing clusters through a crossbar fabric instead of the local buffer when the destination mask indicates that the second primitive output by the first source processing core should be sent to the second processing cluster, wherein the second processing cluster does not include the first source processing core; and rasterizing the primitives in parallel to produce rasterized pixels of an image.