VGFM Screen Format
| Format type | Image |
|---|---|
| Hardware | VGA |
| Colour depth | 8-bit (VGA) |
| Minimum size (pixels) | 320×200 |
| Maximum size (pixels) | 320×200 |
| Palette | External |
| Plane count | 4 |
| Transparent pixels? | No |
| Hitmap pixels? | No |
| Games |
The VGFM Screen Format is used by Vinyl Goddess From Mars to store full-screen images, primarily for the user-interface.
Signature
There is no signature. Files will always be 64000 bytes, which causes confusion with identically sized raw VGA images.
File format
The file consists of 64000 bytes of data. Each byte is one pixel, however the data is arranged in planes. See Planar VGA for details on the pixel arrangement.
The following formula can be used to calculate target coordinates from a file offset:
width = 320 planeWidth = width / 4 srcX = offset % planeWidth srcY = offset / planeWidth destX = srcX * 4 + srcY / height destY = srcY % height; image(destX, destY) = file[offset]
Alternatively, assuming the target is a 320×200 byte array in standard VGA layout, this simpler algorithm can be used:
width = 320 height = 200 planeWidth = width / 4; planeSize = planeWidth * height; output[i % planeSize * 4 + i / planeSize] = input[i];
Credits
This file format was reverse engineered by Malvineous. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)