Conservative rasterization using gradients

A method of performing conservative rasterization in conservative rasterization hardware, the method comprising:

• calculating, in each of a plurality of first hardware sub-units, for a different edge of a primitive, an outer coverage result for the edge and an inner coverage result for the edge for each pixel in a microtile of a rendering space, wherein the rendering space is sub-divided into a plurality of tiles, each tile is sub-divided into a plurality of microtiles, each microtile comprising an identical arrangement of pixels;
• and
• wherein calculating for an edge of a primitive, an outer coverage result for the edge and an inner coverage result for the edge for each pixel in a microtile comprises:
• in a first hardware element, calculating a first output using a sum-of-products of the edge and coordinates of a microtile within a tile in the rendering space,
• in each of a plurality of second hardware elements, calculating a second output using the sum-of-products and coordinates of different pixels defined relative to an origin of the microtile,
• in each of two third hardware elements, calculating a third output using the sum-of-products and coordinates of a different pixel corner position defined relative to an origin of a pixel;
• and
• combining, for each output result, a different combination of the first output, one of the plurality of second outputs and a third output.

A non-transitory computer readable storage medium having stored thereon computer executable code that when executed causes at least one processor to perform conservative rasterization in conservative rasterization hardware, the method comprising:

• calculating, in each of a plurality of first hardware sub-units, for a different edge of a primitive, an outer coverage result for the edge and an inner coverage result for the edge for each pixel in a microtile of a rendering space, wherein the rendering space is sub-divided into a plurality of tiles, each tile is sub-divided into a plurality of microtiles, each microtile comprising an identical arrangement of pixels;
• and
• wherein calculating for an edge of a primitive, an outer coverage result for the edge and an inner coverage result for the edge for each pixel in a microtile comprises:
• in a first hardware element, calculating a first output using a sum-of-products of the edge and coordinates of a microtile within a tile in the rendering space,
• in each of a plurality of second hardware elements, calculating a second output using the sum-of-products and coordinates of different pixels defined relative to an origin of the microtile,
• in each of two third hardware elements, calculating a third output using the sum-of-products and coordinates of a different pixel corner position defined relative to an origin of a pixel;
• and
• combining, for each output result, a different combination of the first output, one of the plurality of second outputs and a third output.