[dahart]

This is about taking an analytic sample of the scene with an expression that includes and accounts for the choice of filter, instead of integrating some number of point samples of the scene within a pixel.

In this case, the filtering and the sampling of the scene are both wrapped into the operation of intersection of the square with polygons. The filtering and the sampling are happening during rasterization, not before or after.

Keep in mind a pixel is an image sample, which is different from taking one or many point-samples of the scene in order to compute the pixel color.