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Simple graphics format for Agon computers

This format tries reduce file sizes and make it easy to use/load from any source(network, sd card etc).

Image format

It's simple wrapper for RGB2222 that simplifies loading it from any media and showing it on screen. Data is little endian.

File starts with two bytes header IM(like IMage).

Next goes this two bytes(word) - size of raw data(bitmap) or VDP-packed data size.

After width of image(word) and height(also word).

Next goes status byte - format of stored bitmap:

  • 0x00 - bitmap stored without RLE compression. After this byte RGB2222 bitmap stored as is.

  • 0x01 - bitmap stored with RLE compression. Next goes:

    • Word that counts how many RLE frames are stored

    • RLE frames that built from: first byte - repeats count; second byte - byte that will be repeated

  • 0x02 - Bitmap stored with TurboVega's Algo(that supports depacking on VDP side). Faster and larger image possible(cause limit for 64K size already applied for packed data). After this byte packed RGB2222 bitmap stored.

Format can be extended in future but also it built for making usage simple from any source - RAM, disk etc

Image converter

It uses Python 3 with PIL library.

It can convert PNG, Jpeg and whatever PIL supports - just call it:

./img2agonimg.py botan.jpg botan.agi

And if image fits to buffer of VDP you'll got resulting file

Loader(works with buffered bitmaps)

From basic

Put agi-load.bin to /mos/ directory and you'll have possibility load images directly to VDP from SD card(to specified buffer number). Utility supports loading up to 255 images.

Example usage is:

agi-load 7F example-image.agi

Image will be loaded to buffer 127(buffer number should be specified in HEX).

And after loading images you can draw them using usual VDP sequences for Buffered API for Images:

10 REM Loading images
20 *AGI-LOAD 7F LAIN.AGI
30 *AGI-LOAD 02 BOTAN.AGI
40 VDU 22 3
50 REM SELECTING Image
60 VDU 23, 27, 32, &7F; 
70 REM Drawing it
80 VDU 23, 27, 3, 100; 100;

Example of loading file

Example of usage included as agi-view mos application(you can put it to /bin directory and use as command).

You can specify file name to it - and it will shows you image.

Some test images are included in test/ directory.