1 hour ago, John Chow Seymour said:
Whether the increased resolution will also take up more of the X16's processing power and time, or whether that is more than made up for by the Vera, is not something I'm able to predict and might depend on the situation.
No, it'll definitely take up more of the X16's processing power and time, in particular because you can't just write directly to VRAM, you have to write through the VERA's I/O interface, so there's some preamble you have to do whenever you want to move the VERA's "cursor" into VRAM.
I would assume that someone wanting to make a raytraced 3D game would start by creating a 320-wide bitmap layer, then setting DC_HSCALE and DC_VSCALE to 64, so they're working at 320x240. That's still 3.3X more pixels than the Gameboy, mind you, but I figure a person could reduce the necessary draw surface further through strategic placement of HUD elements in a tile layer and, if it really comes down to knocking out a few last columns or rows of pixels in order to free up CPU time, you could always reduce the size of the display area with DC_VSTART, DC_VSTOP, DC_HSTART, and DC_HSTOP, and I wouldn't be surprised if a lot of folks just don't notice if you're actually running 300x240, or the like, especially on a VGA display. (Just make sure to leave enough VRAM for a double-buffered display of that bitmap layer... you almost certainly can't do 60Hz so you'll want to draw to a backbuffer and only flip between the two during hblank.)