Why is the Amiga display not centered?

[NovaCoder]

Obviously for games and demos (Elude!) that use WB screen modes are fine because you can just use the overscan prefs to center your screen modes (PAL).

It's only hardware banging applications that are all over the place.

[roy bates]

i dont mind the ones that are a few pixals out,but some are shifted way out.

[Amiga1992]

Originally Posted by NovaCoder

It's only hardware banging applications that are all over the place.

That means, most every game and demo out there :P

[NovaCoder]

All of my ports are 'WB friendly' at least O:-)

[andreas]

Sure thing, because these are not from the old days as the ones we are referring to here.

There was one possible theory I had for these "centering flaws" some time ago. It might be total hogwash, but don't cry out until you've heard it: the usage of stretched images. Back in floppy disk days, disk space was ridiculously short, so game programmers often used the trick as follows: they made pictures in 160x100 and blew them up to double size. I can even prove that since I've raw-loaded some images just as they were originally put on disk. Original size: 160x100! Might have been the last thing to resort to when sound data size was reduced to minimum required amounts and yet there was only a few (kilo)bytes left on the disk. This - obviously - forced dev team members to become inventive...
It's fairly possible that stretching these pics on 2x size in real-time may occasionally have created some of these display issues this thread is about. (Still, it's only a theory.)

[TCD]

Originally Posted by andreas

I can even prove that since I've raw-loaded some images just as they were originally put on disk. Original size: 160x100!

Can you at least point out one example?

[Amiga1992]

I'm not sure if it has to do with the centering, but that's a very interesting thing indeed. Perhaps you can make a thread with this new topic, as I'd like to see which games have done this, in which pictures!

[prowler]

Yes, nice find, Andreas!

Let's have a new thread on this subject, please!

[StingRay]

Originally Posted by andreas

so game programmers often used the trick as follows: they made pictures in 160x100 and blew them up to double size.

Often is quite a relative term. While some coders might have done this I'm quite sure the majority just used normal compression algorithms instead of using such cheap tricks which looked quite horrible, specially when things like (bilinear) filtering would have taken much too long on a plain 68000 A500.

Hence I'd really like to see some examples as well!

Originally Posted by andreas

It's fairly possible that stretching these pics on 2x size in real-time may occasionally have created some of these display issues this thread is about.

This just doesn't make sense at all. The scaling of these pictures back to their original resolution will not affect the display in any way!

[andreas]

Often is quite a relative term. While some coders might have done this I'm quite sure the majority just used normal compression

Heh. I should have added that I mainly rummaged around on disks I didn't need to rip to files first, i. e. ADOS ones, which mostly only contained easily convertible .IFFs.

specially when things like (bilinear) filtering would have taken much too long on a plain 68000 A500.

Oh my. I was mainly referring to these kinds of images used in pre-1990 games (my most active days). You can't associate this way of thinking to HAM, EHB or other kinds of "higher-quality" images (e. g. Starbyte's Tie-Break title screen, intl. version). The ones I speak of would just use a "household" number of bitplanes and be satisfied with a simple pixel resize.

Nevertheless, may I repeat again: it was just a theory. Whilst it could as well have made sense because this is old hardware notorious for having its "little imperfections" here and there (same as with e. g. vintage analog synthesizers).
Alright, although finding an example may take some time, I WILL surely find one, since on my side, rummaging on disks usually goes in line with adventure games I am stuck in; adventure games using static pictures, that is. My "discovery" was that once I had started searching for an in-game screen ( = picture) giving me a hint on how to continue in the game, I was like... yikes! When I pulled that off the disk, it turned out ridiculously small...oversized postage stamp size, so to speak!
Not until I doubled the size, it looked the same as in the game.

[TCD]

Er... have you actually read this thread and seen which games were used as examples for that behaviour? I'd say your theory has indeed nothing to do with what Akira is talking about.

[andreas]

Originally Posted by TheCyberDruid

Er... have you actually read this thread

Oh yes, I have. And unlike others, I have at least stayed on topic and not brought up some emulation theories, mind you.

and seen which games were used as examples for that behaviour? I'd say your theory has indeed nothing to do with what Akira is talking about.

So? You may. I'm not intending to go into an argument because of that. Plus, I did warn about it possibly proving wrong in the long run. So just ignore it.
In short:
I know about vintage synthesizers, which are "old hardware" by definition.
And I know about vintage computers, which too are "old hardware" by today's standards.
And old hardware has been known not to be 100% perfect and predictable, so prone to inaccuracies.
And scaling an image which originally is HALF size to FULL size may (or may not) be affected by these inaccuracies. Because the scaling is done with this hardware, and the scaling routine can be bypassed if the pic is already in desired size.

[TCD]

All the examples are clearly not 160x100 images scaled up. I'd happily continue this argument if your point wasn't so ridiculous I'll still wait until your 'warning' becomes a reality, even if it's just in your head

[andreas]

Originally Posted by TheCyberDruid

I'd happily continue this argument if your point wasn't so ridiculous

You ALWAYS love to continue an argument up to the point of no-go, I am well aware of that. And that's the reason why I'm definitely not going to do that with you. Since all you want is letting the other appear as a complete idiot and you as the "lucky winner". (I can already sense that at an early stage, mind you.)

That, to say it with your wording, IS "ridiculous".

[TCD]

You really thought this one through, didn't you? I say that your argument is pointless in this thread as none of the giving examples matches your argumentation. Yet you don't fail to state: "It's fairly possible that stretching these pics on 2x size in real-time may occasionally have created some of these display issues this thread is about." Since you already stated that it'll take quite some time to dig up your un-related examples, I shall happily resign from this for now.

By the way, I just love to see you struggle for getting your arguments through even if you don't have a clue what you're talking about

[andreas]

I give up.
Never go into an argument with a person that has to have an "opinion" to 50 topics per day on one single forum. That must hollow one's head out so much that it becomes a dangerous case in no time. These people think they know it all. About any possible topic. These people must ALWAYS have the last word with everything. With the permanent intention to "win" over people whose arguments they don't like or whose personality they don't like or both.-- It feels a bit like "discussing" with these AI simulators that were all the rage in the mid-1980's (e. g. "Eliza". C64). "Eliza" did have an answer on all questions; whether they were taken from a knowledge base it didn't matter; at least there was an answer that sounded well-knowledgeable in almost any subject. And people were happy - wow!

even if you don't have a clue what you're talking about

Let's hope you do at least. Should we start a poll?

[VincentGR]

I have this problem :



On a Sony Trinitron 21" and on a on Grundig 15"

On LCDs no problem at all.

[Retro-Nerd]

The Sony Trinitron has a "Picture Rotation" option in Detail Set Up. Should do the trick.

[VincentGR]

Originally Posted by Retro-Nerd

The Sony Trinitron has a "Picture Rotation" option in Detail Set Up. Should do the trick.

Thanks!

The panel is damaged and I can't set anything, I have to press many times something to do the right job. It does whatever it likes and the ir is damaged too.

[Mrs Beanbag]

On Amiga if you want to do horizontal hardware scrolling you have two options: set DDFSTRT (data fetch start) 16 pixels further to the left and lose a hardware sprite, or set DIWSTRT (display window start) 16 pixels further right and lose the left 16 pixels of the imagine. A lot of game designers obviously wanted that 8th hardware sprite so bad. It results in a playing screen 304 pixels wide and off-centre towards the right hand edge.