Wolfenstein 3D IS technically possible on stock A500 shocker!

[Hattig]

There is one way around writing multiple writes for a single pixel, but it isn't very good: 2 color graphics. You can use sprites to color things up, and a copper list to provide some "shading" top to bottom but thats about it.

Unfortunately C2P on a 68000 can't go fast enough. 4 color might be close but that is 4 writes per pixel, in addition to the half dozen instructions needed to calculate the pixel in the first place.

I thought the point of fast C2P was to calculate a chunky buffer of graphics data 16 pixels wide (32 on AGA, any height as Wolf3D/Doom engines are column rendered due to the ray casting mechanism), and then do the C2P on this buffer into planer graphics memory? You still do the write per plane, but you do it for 16/32 pixels at a time rather than 1, thus saving writes.

[Hattig]

@Changing a single pixel in a planar mode requires a shitload of instructions, whereas changing a chunky pixel requires 1 instruction.

Damn right - but changing 16 aligned consecutive pixels in planar mode requires the same amount of instructions. C2P from 16 chunky pixels in fast ram to chip RAM does save a lot of bandwidth over the worst case scenario.

It's just that pretty much any programmer would implement this - however C2P involves a lot of ORing and shifting - precisely what Akiko does for free on the CD32. I'm sure someone has done something fast with pre-calculated lookup tables but on a 7MHz 68000 it's still very heavy.

But doable in a smaller window, 2x1 pixels, lower framerate (not for action FPSes, but fine for RPGs), etc. If a 4MHz Z80 can render a semblance of Wolf3D graphics (http://www.youtube.com/watch?v=COH55Uj53TY) then an A500 can as well.

[Hattig]

I definitely agree with you, but I just have to point out that your video example is not entirely real time - it's still far from from an interactive engine in that distances and texture coordinates are precalculated, as is explained in the video description. I'm sure you know this, but just before anyone else goes into a frenzy

True, but we are talking about the rendering aspect at the moment, rather than the calculation aspect. :-) I expect the calculation will kill the Z80 version, and be tough on a 68000 even with lookup tables.

[Hattig]

What's "copper interleave" - the only references I can find on Google are this thread, and another post by you regarding Atari ST emulation on the Amiga?

It can't be relating to ILBM, as that's a file format that merely stores planar graphics on a row-by-row basis.