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fbergama / pigfx

PiGFX is a bare metal kernel for the Raspberry Pi that implements a basic ANSI terminal emulator with the additional support of some primitive graphics functions.
MIT License
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color pallets? / typo in terminal_codes.txt #44

Closed lindoran closed 3 years ago

lindoran commented 4 years ago

Is it remotely possible to create swap-able pallets? Looking at porting old code from mode 13h, and I noticed the 256 color Xterm pallet is close but the order is different due to the way that it is organized; so old code which uses a decimal color value (like the PiGFX interface) will output different colors. This facilitates the need for at the very least a conversion table (256 bytes of information). But even then the colors are off slightly. For example mode 13h (VGA / MCGA) color 1 is a blue hue RBG 0,0,170. The closest equivalent in XTerm is 19, which is 0,0,175. I guess what I'm asking is could a set of control codes be implemented to replace a color something along the lines of esc[68;5;{color to replace};{red value};{green value};{blue value}m. This would be reset to defaults by esc [m.

Alternatively a few select-able default pallets would be nice, like 13h (VGA/MCGA), CGA, EGA and TANDY perhaps? I can help with researching what the default values are, i have collected some links with good information as to what the RBG values are for each.

also I was looking over /doc/terminal_codes.txt there is a typo the clear sprite code which reads esc[#;x, but should read esc[#x. Its probably a big ask, I was just wondering

chregu82 commented 3 years ago

I think this would be a very nice feature to be able to swap the color palette. I would probably define different palettes like Xterm, VGA, maybe others too. Xterm would be the default. I also could imagine to define a custom palette in a file on the compact flash. Palettes could be switched with a control code. Could you provide the links you wrote about?

lindoran commented 3 years ago

absolutely -- here is a link with the RBG values to decimal color number for VGA (mode 13h): https://www.freebasic.net/forum/viewtopic.php?t=17474 about mid way down there is a full broken out chart in ascii for the 256 color palette in order with RGB values.-- I wish there was a better example of this, perhaps I will have to make one ... I really looked for a long time. This is the best I could find. This is the less than helpful wikipedia article but it does have good other related information https://en.wikipedia.org/wiki/Mode_13h. This is yet another page on the VGA mode 13h palette: https://www.fountainware.com/EXPL/vga_color_palettes.htm

Here is ega, with the RGB values in hex http://www.shikadi.net/moddingwiki/EGA_Palette. To change from RGB take the hex value, each 2 digit pair is the color value in decimal. so 1 - blue #0000AA is 0,0,170. I think this pallet is very close to the first 16 of mode 13h (vga or MCGA).

here is a link to the C64 color pallet and the color values by decimal color numbers (a chart near the bottom) - https://www.c64-wiki.com/wiki/Color

This is for CGA: https://en.wikipedia.org/wiki/Color_Graphics_Adapter -- the values are listed in HEX for the character mode colors, but they are also the same colors for the composite mode for CGA .... There's also a good breakdown of the various 4 color pallets for graphics mode. this might be useful to have as well.

this is for the Tandy Graphics Adapter found on the tandy 1000 / PCjr: https://en.wikipedia.org/wiki/Tandy_Graphics_Adapter

it's kind of a rabbit hole lol; I hope this helps :)

On Wed, Sep 30, 2020 at 2:37 AM Christian Lehner notifications@github.com wrote:

I think this would be a very nice feature to be able to swap the color palette. I would probably define different palettes like Xterm, VGA, maybe others too. Xterm would be the default. I also could imagine to define a custom palette in a file on the compact flash. Palettes could be switched with a control code. Could you provide the links you wrote about?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/fbergama/pigfx/issues/44#issuecomment-701218223, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQIK5ZELBCQ3BUM43QTXOVDSILN4HANCNFSM4R5IGK3A .

-- if only there was an endless river of information, connecting the world's computer systems; simply cataloging and indexing useful information.... sigh oh well.

chregu82 commented 3 years ago

Please take a look at the develop branch. I implemented the ability to change the palette to VGA or C64. CGA and EGA colors seem to be part of the standard VGA color table. I am unable to test this at the moment, as I don't have a Pi with me. So maybe it doesn't work at all. Feel free to test it. At the moment it's not yet possible to load a custom color palette.

lindoran commented 3 years ago

I'm at work for 10 hours I'll look whebt I get home thanks!

On Wed, Sep 30, 2020, 7:39 AM Christian Lehner notifications@github.com wrote:

Please take a look at the develop branch. I implemented the ability to change the palette to VGA or C64. CGA and EGA colors seem to be part of the standard VGA color table. I am unable to test this at the moment, as I don't have a Pi with me. So maybe it doesn't work at all. Feel free to test it. At the moment it's not yet possible to load a custom color palette.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/fbergama/pigfx/issues/44#issuecomment-701363326, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQIK5ZBVSISMPSFBM3C7DC3SIMRGPANCNFSM4R5IGK3A .

lindoran commented 3 years ago

the VGA pallet works as does the C64 Palette testing was done on the Pi-0 1.3 I ran a fractal from source and compared to output from the authors web page. all appears to be working and well. I wish I could test on a larger pi but I don't have one with functioning TX pins at the moment.
(C64) PXL_20201001_044039696 (VGA / mode 13h) PXL_20201001_040556559

lindoran commented 3 years ago

as stated, I didn't try custom but everything else seams to work so thanks :)

chregu82 commented 3 years ago

Custom palette is done now too.

lindoran commented 3 years ago

I'll check it out in a bit :)

On Sat, Oct 3, 2020, 2:02 PM Christian Lehner notifications@github.com wrote:

Custom palette is done now too.

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lindoran commented 3 years ago

Custom is working on the pi-zero, manually programed in a mock 4 color CGA mode it's working perfectly, :) thanks for this! really pushes this project into a new light, very few terminal's like this. 👍