chips44 / hagl_pico_vgaboard Goto Github PK

Would permit to demonstrate how to integrate hagl_pico_vgaboard in a real another project.

cf. https://en.wikipedia.org/wiki/Commodore_64#Graphics

Like 640x360 (1280x720) or 800x450 (1600x900).

2 times F80800???

cf. https://en.wikipedia.org/wiki/Color_Graphics_Adapter#Color_palette

Already done at source level.

cf. https://en.wikipedia.org/wiki/Grayscale#Converting_color_to_grayscale:

luminance = 0.2126 * r + 0.7152 * g + 0.0722 * b

Here we have r, g and b from 0 to 31 and no FPU...

Could use binary 2048 bytes (for 8x8 256 glyphs fonts) from https://github.com/viler-int10h/vga-text-mode-fonts/ without further ado.

cf. https://www.designpieces.com/palette/game-boy-original-color-palette-hex-and-rgb/.

All these modes share the same 48K (49152 bytes) of memory for framebuffer:

• 1024x384x2 (1bpp)
• 512x384x4 (2bpp)
• 512x192x16 (4bpp)
• 256x192x256 (8bpp)

"Weird" modes:

• 512x768x2 (1bpp)
• 256x384x16 (4bpp)

cf. https://reuse.software/.

cf. https://www.raspberrypi.com/documentation/pico-sdk/high_level.html#pico_unique_id

There is now a better way to implement srand() than the srand_rosc() implemented in the example.

cf. https://www.cpcwiki.eu/index.php/CPC_Palette

27 colors in an 3x3x3 RGB cube

Default palettes to be found:

• Mode 0 160x200 16 colors
• Mode 1 320x200 4 colors
• Mode 2 640x200 2 colors : blue background with yellow foreground

cf. https://lospec.com/palette-list/console16

Should be reordered to have black at index 0 and white at index 15?

Short:

• A go to next demo
• B go to next palette
• C change letterbox borders randomly

Medium:

• A go to first demo
• B go to first palette
• C change letterbox borders to black

NB: no use of Repeat feature for now!

cf. https://github.com/tuupola/embedded-fonts, especially https://github.com/tuupola/embedded-fonts/blob/master/misc/viznut/include/unscii-8-fantasy.h

cf. https://www.raspberrypi.org/forums/viewtopic.php?f=145&t=305712&start=50#p1864822

This would need a simple way to display text, but even a simple 8x8 font with ASCII or CP437 support would be fine.

https://lospec.com/palette-list/dawnbringer-16

cf. https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit

cf. https://fontstruct.com/fontstructions/show/1334143/tic-computer-6x6-font.

it's published as binary in https://github.com/nesbox/TIC-80/blob/main/src/core/font.inl.

see https://fontstruct.com/fontstructions/show/1651619/5x5-font-monospaced, too.

It's the resolution of my LG L204WT monitor...

cf. http://tinyvga.com/vga-timing/1680x1050@60Hz

Perhaps 840x525 should be sufficient by dividing horizontal timings and 147.14 MHz pixel clock by 2?

See scanvideo/demo1/demo1.c in pico-playground example.

cf. https://github.com/X16Community/x16-emulator/blob/r46/src/video.c#L195

NB: 256 colors 12 bits RGB palette, with C64 palette at 0-15

And initialize it on core1!

Shouldn't be too hard...

https://fontstruct.com/fontstructions/show/1334143/tic-computer-6x6-font is public domain alike (CC0).

https://fontstruct.com/fontstructions/show/1651619/5x5-font-monospaced has other choices for some lowercase letters, but license is "This FontStruction is licensed under a FontStruct Non-Commercial License".

• https://lospec.com/palette-list/chromatic16
• https://lospec.com/palette-list/na16
• https://lospec.com/palette-list/pico-8
• https://lospec.com/palette-list/cartooners

cf. https://forums.raspberrypi.com/viewtopic.php?t=347638#p2082565

I'm seeing an excellent work towards video scanline generation with framebuffer, that gets limited by current rpi memory footprint.
My question would be if its possible to create a virtual 640x480 multicolor space using huffman compression to allow direct usage of this framebuffer.

NUL chars in the text buffer should not be rendered at all, others will render with background and foreground colors instead of framebuffer content, without transparency.

Palette can be different from the framebuffer's one.

This does not need to use multiplane capability of scanvideo, unless it is easier or faster than "naive" rendering.

Text "cells" could be 2 to 4 bytes:

• 8 bits for char to display
• 4 or 8 bits for background color
• 4 or 8 bits for foreground color
• 4 or 8 bits for font (index) to use

Text mode could have these attributes:

• (array of) font to use (TODO, only 8x8?)
• lines as framebuffer pixel width / font width (or just 8?)
• columns as framebuffer pixel height / font height (or just 8?)
• cursor:
  • shape: horizontal line or block (and/or reverse block and/or vertical line?),
  • animation: off, fixed, flashing slowly or flashing quickly,
  • current line,
  • current column

This could be the base for a "dumb" terminal understanding a subset of ANSI/VT100 sequences.

cf. http://tinyvga.com/vga-timing/1280x800@60Hz

cf. https://tomverbeure.github.io/video_timings_calculator

cf. https://github.com/kilograham/b-em/blob/pico/src/pico/video/display.c

Instead of a section in REDME.