In riApp.cpp, renderStroke(), path->stroke() fills in covBuffer[] with coverage values, then calls pixelPipe->pixelPipe() in a loop to plot each pixel with a coverage filter that is effectively a box.

Why doesn't path->stroke() plot the pixels itself without having this covBuffer[] thing?

Modifying the code to do this shows little difference in the appearance of a diagonal 1-pixel wide line, and saves memory from having to allocate covBuffer[].