No, there's no deltas in that sense. I just mean that I've got two
routines — DrawBlock and DrawBlank — each of which draws a whole tile
at (hl) and then returns. Betraying my dense level of thought, they
both look essentially like this:
ld (hl), b
inc l
ld (hl), c
inc l
... etc etc ...
A quick mental calculation suggests I could go full screen again if I
switched to subverting the stack pointer. I wrote both by hand for
expediency, so it's no surprise they're suboptimal. I had a go with
drawing on the half-byte too for a proper pixel scroll but the
read/modify/writes killed performance (or, rather, my attempt at them
did). I guess either 16x16 tiles (for half as many shared borders) or
a vertical scroll would be potential solutions; a vertical scroll
would also fix my clipping without any trauma, I guess — I can easily
spare gutter space on either side.
I think it'd be nice to go full screen and properly clipped one way or
the other just to prove the point; I'm not sure I have your sort of
willpower for finishing a whole game beyond that. Though if it was a
simple run and jump, I guess there wouldn't be that much to it?
On 15 May 2012, at 01:10, Balor Price <[email protected]> wrote:
> Nice!
>
> When you say the tiles are 'precompiled', have you used a sprite builder
> to print the deltas? If so, I'm confused about the left-hand clipping
> if there's no real scrolling involved. Surely you're not printing all
> those tiles each frame?
>
> Howard
>
>
> On 15/05/2012 00:32, Thomas Harte wrote:
>> It's exceedingly rough and a pretty simple effect that I'm sure has
>> been exploited a hundred times before but I thought I'd throw it up as
>> is as my part in maintaining the fantastic momentum we've had lately.
>>
>> http://www.clocksignal.com/dropbox/scroller.dsk
>>
>> It's explicitly not a mere demo effect; adding some sprites and making
>> a full game is a definite possibility, though you'd probably want to
>> drop to 25fps — there's loads of memory free even on a 256kb machine
>> and it's a full, genuine Mode 4 display. The map itself is just an
>> array of bytes in memory, so there's no real magic there and no huge
>> footprint. The workflow is based on a cross-platform map editor called
>> Tiled so that's easy to manage.
>>
>> Beyond my painful lack of artistic ability there's no reason why it
>> need use only one tile. Ditto for proper clipping at the edges (which,
>> because the tiles are precompiled, would cost more RAM but not really
>> any more processing).
>>
>> It was full screen until the last minute, when I discovered that some
>> sections of the horrid little map I've hastily scribbled were a little
>> too slow. As you'd expect on a Sam, the trick is painting only where
>> you need to so level design affects speed in a less obvious manner
>> than being directly tied to screen area.
>>
>
