Rainbow on text mode

[pfeuh]

Hello,

 

Perhaps a newbie question... Is it possible to get a rainbow on a text on default video mode? It seems that I get only a luminosity variation...

 

RAINBOW.XEXrainbow.ccompile.sh

Edited July 26, 2020 by pfeuh

[Rybags]

The 320 pixel modes including default text Gr. 0 don't allow independent colour from the background (unless you have VBXE or Sophia but that's sort of irrelevant).

 

There's a trick using PM graphics to overlay the pixels at least partially to allow more colour but generally not used a lot and with limitations given that you can only cover 1/4 of the screen without extra trickery.

[Graham Dearsley]

Yep GR.0 only gives you shades of the background colour for your text. You could use  DLI's to change the background colour on every line but obviously that changes the background colour ?.

 

If you can put up with double width characters then GR.1 gets you 4 colour text and then you CAN use DLI's to change just the text colour on every line.

[pfeuh]

Thanks, guys. I'm trying the GR.1... But 20 columns... That's poor! By the way, you don't need to use a DLI, a rainbow can be done without it thanks to WSYNC & (RTCLOK + 2), as in my example program above.  

[Graham Dearsley]

Yep again, so you can ?

 

[Irgendwer]

19 hours ago, pfeuh said:

Thanks, guys. I'm trying the GR.1... But 20 columns... That's poor! By the way, you don't need to use a DLI, a rainbow can be done without it thanks to WSYNC & (RTCLOK + 2), as in my example program above.  

 

You may like to inspect this too:

 

https://atariage.com/forums/topic/261463-c-or-assembler-for-game-development/?do=findComment&comment=3690336

 

 

[pfeuh]

Yeah, awesome! I notice the use of the structure GTIA_WRITE which is really easy to read and understand, I didn't realized until I read your C code that all Atari chips were implemented as structures in cc65. Yesterday, I've done a rainbow as a part of assembler in cc65. I missed just one thing, it is ANTIC.vcount. The way I used to synchronize was counting the number of WSYNC I did... I suppose that using ANTIC.vcount will simplify the task. Thanks again.

[atarixle]

On 7/26/2020 at 4:53 PM, pfeuh said:

Thanks, guys. I'm trying the GR.1... But 20 columns... That's poor! By the way, you don't need to use a DLI, a rainbow can be done without it thanks to WSYNC & (RTCLOK + 2), as in my example program above.  

Use Graphics 12 or 13 (that's the character equivalent to Graphics 7 and 15). It got up to 5(!) colors, and practically is used with custom font sets. Many polish games use it for shadowed text, and with the right tricky design, it sometimes isn't even notable at the first glance that it has just half the resolution.

Edited July 27, 2020 by atarixle

[Graham Dearsley]

I think that just 1 colour is enough for the rainbow routine but it has to be independent of the background colour if you don't want that to be a rainbow as well ?. 

[pfeuh]

2 hours ago, atarixle said:

Use Graphics 12 or 13 .../..... with the right tricky design, it sometimes isn't even notable at the first glance that it has just half the resolution.

I would like to make a film credits in French with a rainbow on the text, it means with an extended characters set, easy to read... Which is not possible with a 4x8 character set.

 

With a rainbow in background, reading the text is hard, and with a rainbow on the text, the effect is ugly as there is no color change, only luminosity. I've done a workaround, I do a rainbow over and under the scrolled text.

 

The program is "A", must be loaded without basic. I tested only 50hz and only on Atari800 emulator. Choose the option "G" ( = "Go!") and press START, later OPTION to go back to the menu, No need to load text or font, a default set is already loaded with the program.

 

Still having some problems with scrolling at slow speed. Later, I will have to fight with 4ko boundaries for big credits.

 

DISK.XFDatariCreditsRoller.zip

 

 

 

 

 

 

 

[thorfdbg]

What you can do is to set the background color of Antic 2, i.e. $d018 to the rainbow color AND $F0, and the foreground color to the rainbow color itself. This will give you the full rainbow on the text, but a (dull and dark) rainbow on the background.

[pfeuh]

Thank you, I'm going to try that.

 

It works, but it's not pretty.

 

TEXT_RAINBOW.XFD

Edited July 28, 2020 by pfeuh
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