amiga.org
     
iconAll times are GMT -6. The time now is 05:26 PM. | Welcome to Forum, please register to access all of our features.

Amiga.org Amiga computer related discussion Amiga Hardware Issues and discussion Why screen size varies across games?

Amiga Hardware Issues and discussion This forum is dedicated to the discussion and resolution of issues related to Classic and Next Generation Amiga hardware. Got a problem with a piece of hardware? Click to speak.

Reply
 
Thread Tools Display Modes
Old 06-24-2010, 02:18 PM   #1
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Why screen size varies across games?

Can anyone enlighten me why some Amiga games are displayed in full screen, some games take up about 3/4 of the screen and some games some other weird portion of the screen? Is it to accelerate games when they use less of the screen? I've also noticed that AGA games are more likely to run full screen than not. Why? Is there a way to force games to use full screen?
pkupcik is offline   Reply With Quote
Old 06-24-2010, 02:28 PM   #2
Karlos
Sockologist
Points: 50,618, Level: 100 Points: 50,618, Level: 100 Points: 50,618, Level: 100
Activity: 5% Activity: 5% Activity: 5%
 
Karlos's Avatar
 
Join Date: Nov 2002
Location: Barishabaad, Sardistan
Posts: 16,667
Blog Entries: 18
Default Re: Why screen size varies across games?

Quote:
Originally Posted by pkupcik View Post
Can anyone enlighten me why some Amiga games are displayed in full screen, some games take up about 3/4 of the screen and some games some other weird portion of the screen? Is it to accelerate games when they use less of the screen? I've also noticed that AGA games are more likely to run full screen than not. Why? Is there a way to force games to use full screen?
Assuming you have a PAL amiga, the games that appear to be vertically short are those that were designed for NTSC, which has a somewhat lower vertical resolution than PAL.
__________________
OCA
This isn't SCSI... This is SATA!!!
I have CDO. It's like OCD except all the letters are in ascending order. The way they should be.
Core2 Quad Q9450 2.66GHz / X48T / 4GB DDR3 / nVidia GTX275 / Linux x64, AROS, Win64
A1XE 800MHz / 512MB / Radeon 9200 / OS4.1
A1200T BPPC 240MHz / 256MB / Permedia 2 / OS 3.1 - OS3.9, OS4
A1200T Apollo 1240 28MHz / 32MB / Mediator1200 / Voodoo 3000 / OS3.9
A1200D Apollo 1240 25MHz (ejector seat ROM edition) / 32MB
Karlos is offline   Reply With Quote
Old 06-24-2010, 02:33 PM   #3
Speelgoedmannetje
Guru Meditator
Points: 28,025, Level: 98 Points: 28,025, Level: 98 Points: 28,025, Level: 98
Activity: 5% Activity: 5% Activity: 5%
 
Speelgoedmannetje's Avatar
 
Join Date: Oct 2002
Location: Groningen, the Netherlands
Posts: 9,618
Send a message via MSN to Speelgoedmannetje Send a message via Skype™ to Speelgoedmannetje
Default Re: Why screen size varies across games?

I guess you're European?
The Amiga PAL resolution is 320x256, while the American resolution is 320x200.
Also, AtariST and PC games were back in those days at the 320x200 resolution. It saves a hell of a lot of coding keeping a game at just one resolution when having to port it to multiple systems.
But some games, like Lionheart, I think is kept at a lower resolution to maintain speed.
__________________
And the canary said: 'chirp'
Speelgoedmannetje is offline   Reply With Quote
Old 06-24-2010, 02:55 PM   #4
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Re: Why screen size varies across games?

I have PAL A1200 and tried using it with composite output on PAL TV or RGB PAL to VGA NTSC converter on computer monitor - both with the same result. Most of the games are too short, e.g. Lotus, Lemings, Street Fighter, Chuckie Egg, Test Drive, etc. Some seem to be just a little bit short, say 1/5 of a screen which would probably explain the PAL vs NTSC optimization, but some are way short, like 1/3 of the screen, eg. Lotus 2. Most of the AGA games I have seem to be either full screen or just 1/5 too short.
pkupcik is offline   Reply With Quote
Old 06-24-2010, 02:57 PM   #5
KThunder
Defender of the Faith
Points: 11,394, Level: 70 Points: 11,394, Level: 70 Points: 11,394, Level: 70
Activity: 1% Activity: 1% Activity: 1%
 
KThunder's Avatar
 
Join Date: Aug 2002
Location: USA
Posts: 1,504
Default Re: Why screen size varies across games?

Amiga applications can also be coded to use overscan. This increases the resolution slightly and allows them to display full screen.

standard 320x200 uses a border around the displayed area. The overscan settings put that higher at something like 356x220 putting the area all the way to the edges to the screen.

There are different settings for some apps like dpaint with normal, overscan and maximum overscan. Games can do this too.
__________________
Oh yeah?!?
Well your stupid bit is set,
and its read only!
(my best geek putdown)
KThunder is offline   Reply With Quote
Old 06-24-2010, 03:29 PM   #6
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Re: Why screen size varies across games?

I looked at Lotus 2 again and it looks like the screen is only about 1/5 short which would be the missing pixels from 256 PAL resolution compared to 200 in NTSC. And because the game has extra black border around the whole screen, the bottom gap looks extra tall (when you add both gaps together) - I guess I was visually tricked thinking the gap is larger than that.
pkupcik is offline   Reply With Quote
Old 06-24-2010, 03:42 PM   #7
KThunder
Defender of the Faith
Points: 11,394, Level: 70 Points: 11,394, Level: 70 Points: 11,394, Level: 70
Activity: 1% Activity: 1% Activity: 1%
 
KThunder's Avatar
 
Join Date: Aug 2002
Location: USA
Posts: 1,504
Default Re: Why screen size varies across games?

so you are using a pal amiga, what are the games? are they pal or ntsc? I think overscan is more likely a reason for the varying size of screens. Overscan uses more memory so many games dont use it.

I have only ever had ntsc amigas and games and the screens on many were different.
__________________
Oh yeah?!?
Well your stupid bit is set,
and its read only!
(my best geek putdown)
KThunder is offline   Reply With Quote
Old 06-24-2010, 04:47 PM   #8
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Re: Why screen size varies across games?

Quote:
Originally Posted by KThunder View Post
so you are using a pal amiga, what are the games? are they pal or ntsc? I think overscan is more likely a reason for the varying size of screens. Overscan uses more memory so many games dont use it.

I have only ever had ntsc amigas and games and the screens on many were different.
Yes I'm using PAL A1200 and I'm in USA, but I do also own PAL/NTSC TV. The games I tried I believe are PAL, e.g. Lotus 2, 3, Lemmings, Indiana Jones, etc.

I just did another test though with Lotus 2. I booted Amiga in NTSC mode by holding the mouse buttons on reboot and when I played Lotus 2 the screen was nicely stretched all the way to the bottom. I guess I will need to try playing games in NTSC mode to have the picture stretched across the full screen. Does anyone know how to force NTSC boot by default?
pkupcik is offline   Reply With Quote
Old 06-24-2010, 05:04 PM   #9
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Re: Why screen size varies across games?

Now I've read somewhere that there's a way to configure WHDLoad to force either PAL or NTSC for each game. Does anyone know how to do that? That would be great if I could pre-configure that on game by game basis.
pkupcik is offline   Reply With Quote
Old 06-24-2010, 05:32 PM   #10
pkupcik
Beginner
Points: 383, Level: 7 Points: 383, Level: 7 Points: 383, Level: 7
Activity: 6% Activity: 6% Activity: 6%
 
Join Date: May 2010
Posts: 42
Default Re: Why screen size varies across games?

OK, I figured it out, I can use TOOLTYPE to configure each game to use PAL or NTSC, that way I configure each game individually depending on whether it looks and works better in PAL vs. NTSC.
pkupcik is offline   Reply With Quote
Old 06-26-2010, 06:08 PM   #11
platon42
Cult Member
Points: 9,459, Level: 65 Points: 9,459, Level: 65 Points: 9,459, Level: 65
Activity: 8% Activity: 8% Activity: 8%
 
platon42's Avatar
 
Join Date: Jul 2002
Posts: 573
Default Re: Why screen size varies across games?

Two issues not mentioned yet: if you start the display at the normal left border AND want to use the horizontal hardware scrolling feature, you will lose the 8th sprite (for each 16 pixels further left you will lose two more sprites each due to overlap with screen dma). Thats why e.g. Turrican has a slightly smaller screen to the left.

Also screen DMA (and copperlists) will take away cycles for blitter and generic chipram access, so turning off the display at an earlier vertical position will leave more cycles for blitting (with complex source combinations) and cpu chipmem access (usually starts happening with 5 bitplanes at ocs/ecs.
__________________
--
Regards, Chris Hodges )-> http://www.platon42.de <-(
hackerkey://v4sw7CJS$hw6/7ln6pr7+8AOP$ck0ma8u2LMw1/4Xm5l3i5TJCOTextPad/e7t2BDMNb7GHLen5a34s5IMr1g3/5ACM
platon42 is offline   Reply With Quote
Old 06-26-2010, 07:58 PM   #12
Daedalus
Cult Member
Points: 9,252, Level: 64 Points: 9,252, Level: 64 Points: 9,252, Level: 64
Activity: 22% Activity: 22% Activity: 22%
 
Daedalus's Avatar
 
Join Date: Feb 2002
Location: Dublin, Ireland
Posts: 880
Send a message via ICQ to Daedalus Send a message via MSN to Daedalus
Default Re: Why screen size varies across games?

@platon42

Yes, this is the reason for having the black borders on the left and right of the screen in Super Skidmarks - if you want all those sprites on screen at once, you need to reduce the screen width to prevent the overlap.
__________________
Engineers do it with precision
--
http://www.robthenerd.com
Daedalus is offline   Reply With Quote
Reply

Bookmarks

Tags
games , size , varies , screen

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump