Open aybe opened 2 weeks ago
joncampbell123
commented
2 weeks ago I don't think this demo intended for the red and green bars to additive blend. Notice how the bars are made to look like they are rotating around each other, switching whichever one is on top as they go.
The TTF output isn't meant for this kind of demo effect. It's intended to display text, that's it.
aybe
commented
2 weeks ago My bad, you are right...
But I didn't dream, went through all demos in the CD and it was another one!!!🥳:
Funny how memories can be at the same time accurate and not...
Another one, it's supposed to wobble but it isn't:
According to the sources, I pressed a key once to get the effect started, waited, but nothing changed.
Other than that, the other demos in the CD do work quite well!
Thanks!!!
joncampbell123
commented
2 weeks ago The wobble one was probably coded for some SVGA chipsets that allow it (I know ATI chipsets do). Most SVGA chipsets don't support it.
The common technique is to play with the HPEL horizontal panning register per scanline. Most cards latch that at display start, so changes mid frame don't count. ATI chipsets let you change it at any time which means it takes effect next line.
The less common one, used by the 1992 demo "Copper" plays with the placement of the hsync pulse and depends on your analog CRT monitor's phase lock loop to make it wobble.
joncampbell123
commented
2 weeks ago S3 chipsets (which is what DOSBox, DOSBox-X, and most forks emulate by default) don't allow changing HPEL per scanline.
To enable it anyway, add to your dosbox.conf:
[video]
allow hpel effects=trueI tried what you suggested but that didn't change anything:
[dosbox]
machine=svga_s3
[sdl]
output=surface
[video]
allow hpel effects=true
[cpu]
cycles=20000
[render]
scaler=normal2x forced
Describe the bug
Almost 30 years ago, I bought this book: 🤣
TTF output didn't work but switching to surface finally shows something:
But I vividly remember these bars would mix like so:
As it was a programming book, the code was provided:
COPPER.zip
Just in case, the archived CD for the book:
https://www.abandonware-france.org/bibliotheque/livres/le-meilleur-programmation-jeux-3d-27/
Thanks! 😀
Steps to reproduce the behaviour
Switch to 'surface' output, start
COPPER.EXE.Expected behavior
No response
What operating system(s) this bug have occurred on?
Windows 11
What version(s) of DOSBox-X have this bug?
2024.03.01
Used configuration
No response
Output log
No response
Additional information
No response
Have you checked that no similar bug report(s) exist?
Code of Conduct & Contributing Guidelines