SNES (and related) support

[robin-raymond]

Some notes for the future: https://mrclick.zophar.net/TilEd/download/consolegfx.txt https://wiki.superfamicom.org/transparency https://megacatstudios.com/blogs/retro-development/super-nintendo-graphic-guide https://en.wikibooks.org/wiki/Super_NES_Programming/Graphics_tutorial https://megacatstudios.com/blogs/retro-development/snes-development-starting-from-scratch https://en.wikibooks.org/wiki/Super_NES_Programming/pixel_editing_tutorial https://www.youtube.com/watch?v=kwAjG2dj5ZM

Related to https://github.com/sehugg/dithertron/issues/8

[robin-raymond]

https://megacatstudios.com/blogs/retro-development/super-nintendo-graphics-read-in-the-voice-of-brendan https://snes.nesdev.org/wiki/Backgrounds https://wiki.superfamicom.org/backgrounds https://forums.nesdev.org/viewtopic.php?t=13610 [direct color] https://wiki.superfamicom.org/palettes https://megacatstudios.com/blogs/retro-development/metatiles https://georgjz.github.io/snesaa01/ https://megacatstudios.com/ru/blogs/retro-development/creating-nes-graphics https://megacatstudios.com/blogs/retro-development/game-development-lessons-from-retro-platforms https://en.wikibooks.org/wiki/Super_NES_Programming/Super_FX_tutorial https://therealmjp.github.io/posts/adventures-in-retro-development-snes-edition/ https://en.wikibooks.org/wiki/Super_NES_Programming/SNES_memory_map https://en.wikibooks.org/wiki/Super_NES_Programming https://georgjz.github.io/snesaa03/ https://megacatstudios.com/blogs/retro-development/creating-nes-art https://megacatstudios.com/blogs/retro-development/sega-genesis-mega-drive-vdp-graphics-guide-v1-2a-03-14-17 https://www.gamedeveloper.com/design/as-snes-turns-25-devs-discuss-its-7-greatest-graphics-innovations

[robin-raymond]

Note: SNES is LSB (least significant bit) stored. Each bit of the bit plane is stored with the least significant bit in the first bit-plane. The next more significant bit is in the next bit plane (and so on).

https://docs.rs/snes-bitplanes/latest/snes_bitplanes/

Each tile is (normally) 8x8 pixels. The data is stored in bitplanes. Each row of the tile fills 1 byte, with the leftmost pixel being in bit 7.

Thus the highest bit is the left most pixel.

https://sneslab.net/wiki/Graphics_Format

[robin-raymond]

Export of SNES now added in https://github.com/sehugg/dithertron/pull/34

[robin-raymond]

This is now merged so feel free to provide feedback since the binary output is untested. Hopefully it's correct but probably it has some issues (especially given the nature of the bit plane encodings).