MVP working!

Nice little bit of SMC and now it can flip between the viewport and buffer versions! Key P flips, but that's flipping every other frame, so I added O for viewport, K for buffer.

And yeah: 25FPS with one frame for user input & SMC, another frame for the actual stack render. All proved by the top border's timing not getting messed up.

So for an actual game / demo... would be down to 12.5 FPS I suspect to actually do game engine stuff! Then again, most games won't be flipping viewports & buffers and changing where to render to!

However - having coded this I properly understand stack rendering now, so it should be easy to use in a game / demo in any way I want. Including, for example, doing smooth vertical scrolling for example!

Some moving!

So we now have 2 forms of this:

• portal on to a full screen
• basic buffer more useful for normal games

Starts in portal mode, z/x reveals 16 col part of it.

P switches to buffer mode, and cat moves left/right.

But P doesn't switch back yet.

But... but... hey multiple variants of stack blitting with SMC!

Basic Viewport Render

Got the basic render done.

All 192 rows of pixels and 24 rows of attrs blitted every frame using stack tricks.

Exact timing allows me to chase the beam for 248 scanlines worth of t-states per frame.

And using the timing for that to stripe the top border. Which also usefully tells me if I ever use too many t-states per frame!

But to move the viewport... it costs too much to LUT during the render loop. So looks like SMC...

Also... all the unrolling is making this 13K already! Not practical for a game or demo... but hopefully learning how to do this should make a basic buffer to screen game render much easier.