Drilbo (Drilbo Represents an Imaging Libary not only for Blorb Objects) is the imaging support library for the fizmo interpreter. It supports the following file input formats:
- JPEG
- PNG
- Z-Machine V6 graphics, MG1 format
Not supported:
- Z-Machine V6 graphics, Amiga and Macintosh format
The following file output formats are supported:
- JPEG in RGB, Grayscale and JCS_YCbCr.
- PPM, P6 variant (usually for testing purposes, P3 variant available, but outcommented in the code).
The following screen output methods are supported:
- X11 display though XLib, Truecolor only.
These imaging operations are implemented:
- Bilinear scaling
All operations use a “z_image” type which holds all the data and metadata for images. A z_image may contain either an RGB or a grayscale file with a depth of 8 bit per pixel.
See “drilbo.h” for more information on the specific functions.
From The Z-Machine-Specification, section 8 (just for reference):
Some details of the known IBM graphics files are given in Paul David Doherty's “Infocom Fact Sheet”. See also Mark Howell's program “pix2gif”, which extracts pictures to GIF files. (This is one of his “Ztools” programs.)
Although Version 6 graphics files are not specified here, and were released in several different formats by Infocom for different computers, a consensus seems to have emerged that the MCGA pictures are the ones to adopt (files with filenames *.MG1). These are visually identical to Amiga pictures (whose format has been deciphered by Mark Knibbs). However, some Version 6 story files were tailored to the interpreters they would run on, and use the pictures differently according to what they expect the pictures to be. (For instance, an Amiga-intended story file will use one big Amiga-format picture where an MSDOS-intended story file will use several smaller MCGA ones.)
The easiest option is to interpret only DOS-intended Version 6 story files and only MCGA pictures. But it may be helpful to examine the Frotz source code, as Frotz implements draw_picture and picture_data so that Amiga and Macintosh forms of Version 6 story files can also be used.
It is generally felt that newly-written graphical games should not imitate the old Infocom graphics formats, which are very awkward to construct and have been overtaken by technology. Instead, the draft Blorb proposal for packaging up resources with Z-machine games calls for PNG format graphics glued together in a fairly simple way. An ideal Version 6 interpreter ought to understand both the four Infocom picture-sets and any Blorb set, thus catering for old and new games alike.