'Z Blast SD'-4k game,Cool game but slows down badly.Is it a difficult task to...

[Puresox]

Stop the severe slowdown?


I am a meer player of games and have no knowledge of programming, so do not have any idea on whether this is a ridiculous question!? Just thought it was a good little game despite the slowdown.
[size=78%]http://www.cpc-power.com/pages/download.php?fiche=3155&dsk=4[/size]

[TFM]

64 bit os sometime lead to a slowdown.

[Puresox]

Thanks.Is that- '64 bit on screen'?


What indicates this? For a layman to understand?

[Nich]

Stop the severe slowdown?

I converted this game from the Spectrum to the CPC, and the answer to your question is "yes". I'll try to explain it in simple terms!

The way the Spectrum stores the screen in memory is quite different to the CPC. On a Spectrum, you can set the inks in any 8×8 block of pixels to black, thus making a sprite appear to be invisible - but you don't need to erase the sprite itself from the screen if you want to move it to another part of the screen. On a CPC, if you set an ink to black, it affects the entire screen, so you have to erase the sprite properly every time you move it. This is the main reason that the CPC version of zblast SD is a lot slower than the Spectrum version.

I could have reduced the slowdown slightly by erasing the entire screen playing area every time , but I decided not to do this as I felt the game would be consistently slow!

Thanks for the compliment about the game, by the way.

[TFM]

Just played the game a minute ago! It's really great!

[Puresox]

Thanks for the explanation, Great little game really enjoyable!

[Puresox]

 Just wondered if I could possibly pick your brains again with regard to this slow down with sprites? I came across another good little shoot em up last night, which is 'Solar Coaster'  this has many moving sprites and runs at a fast pace. Any idea on the techniques to enable this ?http://www.cpc-power.com/pages/download_part.php?fiche=2477&dsk=1&part=Solar%20Coaster%20%28UK%29%20%281987%29.dsk

[Nich]

Just wondered if I could possibly pick your brains again with regard to this slow down with sprites? I came across another good little shoot em up last night, which is 'Solar Coaster'  this has many moving sprites and runs at a fast pace. Any idea on the techniques to enable this ?

Firstly, the sprites in Solar Coaster are smaller than those in zblast SD, so it takes less time to draw them.

Secondly, they aren't drawn in transparent mode. This means that any areas of black are drawn on the screen, and if one or more sprites overlap, you will see that the sprites look like they are drawn within a black box. (Actually, it isn't that noticeable in Solar Coaster because the sprites move quite quickly.)

Drawing sprites in transparent mode takes a lot more time than in non-transparent mode. For each byte of sprite data, you also have to obtain the corresponding "mask byte", use the mask byte to remove pixels from the screen that will be overwritten and preserve the pixels you don't want to overwrite, then write the sprite data byte at the same location on the screen. If you are drawing a sprite in non-transparent mode, you just write each sprite data byte to the screen, with no need for a mask byte.

It is fairly technical, so hopefully you will understand my explanation!

[Puresox]

I think I understand the concept. Anyway thanks for taking the time to put an explanation,Appreciated !

[DARKGATE]

Please someone can made a .CDT file of this game, for play on a real CPC464? 
More support for CPC 464 please. 

[Devilmarkus]

Here you go...

(no title screen!)

[DARKGATE]

  Thank you DEVILMARKUS, thank you.
Guys don't forget the your real AMSTRAD, an emulator is good, but the real machine is the TOP, take the your AMSTRAD and Replay. 

[Gryzor]

Whoa! Lovely little game, despite of the slowdown. It smacks of spectrum-ness