Mandy

A fractal generator for classic 68k Macintosh computers (since 2016).

What it does

Mandy renders three kinds of image into a window, chosen from the Fractal menu:

• Tree — a recursive branching tree, drawn directly with QuickDraw lines.
• Mandelbrot — the Mandelbrot set.
• Julia — a Julia set at a fixed constant.

Mandelbrot and Julia are rendered progressively: the image starts at a coarse block size and refines through several passes down to full resolution, with each pass visiting blocks in a recursive quadrant order rather than a plain top-to-bottom scan, so the picture comes into focus as a whole rather than sweeping like a scanline. Rendering happens a little at a time on idle events, so the application stays responsive while a render is in progress. Command-Period aborts a render early, leaving whatever has been drawn so far on screen.

Other features:

• Get Info a small floating window showing the current fractal's resolution, screen depth, render time, and mathematical parameters (zoom, iteration count, Julia constant).
• Save As... exports the current image as a PICT file.
• Animate / Stop Animation cycles the displayed colours or patterns without recomputing the fractal. On colour Macs this rotates the image's own colour table.

The application automatically detects whether Color QuickDraw is available and renders in colour where possible, falling back to QuickDraw's standard dither patterns (white/light gray/gray/dark gray/black) on black-and-white screens or at 1-bit/2-bit screen depths.

Requirements

• Classic Mac OS, System 6 or System 7.
• 68k Macintosh hardware. The minimum target is a Mac Plus with 1MB of RAM..
• Works on both black-and-white and colour Macs. Colour Macs need Color QuickDraw.
• The window is a fixed 512×300 — there's no resizing or zoom yet.

Building

MandyWindow is written in classic Mac Toolbox C — plain C against QuickDraw, the Window Manager, and the Menu Manager, not Objective-C, Carbon, or Cocoa. It's built with Think C; no other toolchain has been used or tested against it, though it should port to other 68k Mac Toolbox C environments (MPW, CodeWarrior) without much difficulty.

No third-party libraries are required — only the classic Mac Toolbox headers (Quickdraw.h and friends) and the standard ANSI C library that ships with Think C (<stdio.h>, <math.h>).

Source files

File	Purpose
MandyWindow.c	Application entry point and main event loop
mwWindow.c / .h	Fractal rendering, offscreen buffering, window management
mwMenus.c / .h	Menu bar setup and menu command dispatch
mwInfo.c / .h	The Get Info palette window
mwSaveAs.c / .h	Save As... (PICT export)
mwColorCycle.c / .h	The Animate / Stop Animation feature

Known constraints

A few Toolbox routines were deliberately avoided after testing showed they don't work in this project's build/link setup, in case that trips up future changes:

• SetGWorld reliably crashes on real hardware here — ports are switched with plain SetPort instead.
• PmForeColor and CTabChanged (Palette Manager / Color QuickDraw routines) fail to link — colour is set via direct pixel-memory writes and colour-table manipulation instead of these calls.