Perhaps it could be done that way, but the fastest and most straight-forward way of doing it is just plain old multipass rendering. "Motion blur" (or as I like to call it: motion crap) is really just blending the current frame with the previous frame. It's not really blur at all, particulary if the movement inbetween frames is large. True motion blur is notoriously difficult to implement, particulary in the way it is accomplished in the human eye.Titanio said:
Depth of field was done by rendering the same scene from several slightly skewed angles in the old 3dfx T-buffer and then blending the resulting frames (in this case, 4 frames were used). This had the effect that where the difference between the frames were small, the image became sharp. Where the difference was large, it became blurred. I assume that is the way modern games do it as well. Not really sure how this would be done in a shader...
One may want to take note that there's nothing in particular that helps to hide jaggies by these rendering techniques. Obviously jaggies may be less pronounced where several frames overlay and fuzz up the image, but they don't fix the fundamental issue that causes jaggies to appear... On the other hand, there should be nothing on a technical level that prevents xenos from doing these effects WITH AA enabled either. There may be performance issues (particulary with DoF), but that's another issue.
I'm a little wary however of the assumption that xenos eDRAM automatically should have "enough" bandwidth to do 4xAA with no performance hit. DRAM is not 100% efficient, depending on how accesses are done to it, it can either run very fast, or it can run like shit. Random access speed is typically terrible, while linear bursts can run very quickly. Unless there are some kind of SRAM write buffers to hide first-access latencies, refresh cycles and page break penalties and such, chances are on-die bandwidth could be significantly less than theoretical maximum, leading to much higher performance hit than 5% when doing 4xAA...
Also, as eDRAM appears to be single-ported (or else MS and ATi would have stated higher bandwidth figures), it means xenos will be locked out when doing framebuffer read/writes to main memory. This will happen after every completed frame/tile, or several times per frame/tile when doing render to texture ops and/or blur, DoF etc... Hopefully that won't stall the rendering pipeline (as it likely won't have to access eDRAM on every cycle when pixel shading and such), but it could be another slight performance issue early on in the console's life. 3rd generation x360 titles probably won't be hindered much at all by stuff like this I'm sure.
