Recent posts

#1

A

Games / Re: CPC Formula 1 [WIP]

Last post by andycadley - Today at 21:07

Sorry - I think I may have muddled up everything by not explaining well. I meant that you can fit more sprites in mode 1.
For instance - if I were to draw a sprite that is 16*16, I would be able to fit more on the mode 1 sheet.

Well there are half as many pixels across in Mode 0, so you can fit less 16*16 Mode 0 sprites compared to 16*16 Mode 1 sprites. But 16 Mode 0 pixels cover the same physical area as 32 Mode 1 pixels so it's not really a like for like comparison.

Ultimately there is absolutely no advantage to using Mode 1 over Mode 0 in terms of the number of sprites you'll get in a game. The only reasons to choose it are because you need the higher resolution for aesthetic or functional reasons (f.e. you have a lot of text) or because you have art designed for another system with square pixels (typically the Speccy but not necessarily) and don't want to spend time/effort/money reworking it.

#2

Programming / Re: triple buffering

Last post by McArti0 - Today at 21:00

In Jet planes you always have a lot of lag. So it must be Jet simulator games. 

#3

Amstrad CPC hardware / Re: Zilog Z84C0020PEG in my CP...

Last post by McArti0 - Today at 20:34

Hardcore Hardware Patch Z84C - OUT(C),0

Someone tell me if the CMOS output can be shorted with impunity.

#4

L

Technical support - Hardware related / Re: 464 plus to 6128 plus disk...

Last post by lordoftime - Today at 20:32

i have now also fitted the external drive connector and was wondering if i need to do anything to make it the default A drive? i followed the guide with the wire from a pin of the internal drive but it just makes the disc access unreliable.

#5

Programming / Re: triple buffering

Last post by roudoudou - Today at 20:30

in a demo, lag has no meaning

in a game...

that's why emulator authors try to reduce lag...

...sometimes

#6

D

Programming / Re: triple buffering

Last post by djaybee - Today at 19:44

Fast gameplay 50fps with huge explosions . You need to copy 10kB to screen.

Oh, interesting, I hadn't considered that explicitly. Essentially, if most frames take well less than 20ms but some take more than that, having a triple buffer allows to "borrow" time from a short frame into a long latter one.

I think I once did something like that in a demo for the Atari ST: my code took near-constant time, but the music player I used didn't, and I made it so that the average would fit in my 20ms budget (40064 NOPs on the ST). Overall, the delay never added up to more than the size of the bottom + top borders, so my frame boundary never crossed into the visible part of the display.

#7

S

Games / Re: CPC Formula 1 [WIP]

Last post by sigh - Today at 18:35

Was thinking that with the mode 1 graphics, you would have more graphics space for sprites?

It doesn't really work like that, Mode 1 has twice the horizontal resolution and half the colours, so the end result is graphics take the same amount of memory to fill the same physical space

You could save memory by reducing the colour depth of stored graphics and converting them on the fly but that loses speed (and it doesn't really matter what the target Mode is at that point).

Then I have been completely wrong all this time!

I thought a mode 0 sprite sheet that is 160x200 was 8kb and a mode 1 sprite sheet that is 320x200 was also 8kb?

160*200*16 = ~16K
320*200*4 = ~16K

You have to drop in colour depth or resolution to actually save memory.

Sorry - I think I may have muddled up everything by not explaining well. I meant that you can fit more sprites in mode 1.
For instance - if I were to draw a sprite that is 16*16, I would be able to fit more on the mode 1 sheet.

#8

A

Games / Re: CPC Formula 1 [WIP]

Last post by andycadley - Today at 18:27

Was thinking that with the mode 1 graphics, you would have more graphics space for sprites?

It doesn't really work like that, Mode 1 has twice the horizontal resolution and half the colours, so the end result is graphics take the same amount of memory to fill the same physical space

You could save memory by reducing the colour depth of stored graphics and converting them on the fly but that loses speed (and it doesn't really matter what the target Mode is at that point).

Then I have been completely wrong all this time!

I thought a mode 0 sprite sheet that is 160x200 was 8kb and a mode 1 sprite sheet that is 320x200 was also 8kb?

160*200*16 = ~16K
320*200*4 = ~16K

You have to drop in colour depth or resolution to actually save memory.

#9

Amstrad CPC hardware / Re: Zilog Z84C0020PEG in my CP...

Last post by VincentGR - Today at 17:54

Thank you.

#10

Amstrad CPC hardware / Re: Zilog Z84C0020PEG in my CP...

Last post by McArti0 - Today at 17:38

Can you also test Relentless? (sound)

GamePlay work. Sound noise (Intro and Game).