FractalForge v0.4.0

FractalForge is a fast, modern fractal explorer for people who know Fractint and XFractint. It's an independent, clean-room GPL-3.0 implementation: it contains no Fractint source code.

v0.4 is the first release for Ubuntu and Windows. The app and its features are the same as v0.3 on every platform, including deep zoom, 3D transforms, stereograms, formulas, L-systems, IFS and the orbit types.

The Linux and Windows packages are new and haven't had much testing yet. If something doesn't work, please open an issue.

Downloads

File	For
FractalForge-0.4.0-macos-universal.dmg	macOS 11 or later, Apple silicon and Intel
fractalforge_0.4.0_amd64.deb	Ubuntu 22.04 or later and distributions based on it (Linux Mint, Pop!_OS, elementary OS …)
fractalforge-cli-0.4.0-linux-x86_64.tar.gz	the command-line renderer for Linux
fractalforge_0.4.0_x64_en-US.msi	Windows 10 or later (64-bit), installer
FractalForge-0.4.0-windows-x86_64.zip	Windows, portable: the app and the command-line renderer, no installation
SHA256SUMS.txt	checksums of all of the above

Ubuntu

sudo apt install ./fractalforge_0.4.0_amd64.deb

FractalForge then appears among your applications, and GIF files can be opened with it.

Windows

Run the .msi. It isn't signed yet, so SmartScreen may say "Windows protected your PC": click More info, then Run anyway.

macOS

Open the disk image and drag FractalForge to Applications. The app isn't notarized by Apple, so the first time you open it macOS says it can't check it for malicious software. To open it anyway:

1. Try to open FractalForge once, and close the warning.
2. Open System Settings → Privacy & Security, scroll down, and click Open Anyway next to the FractalForge message.
3. Confirm with your password.

Or, in Terminal: xattr -dr com.apple.quarantine /Applications/FractalForge.app

Other changes since v0.3

• Releases are now built automatically for all three platforms.
• On Windows the app opens without a console window.
• On Linux, the window identifies itself as FractalForge, so desktops can match it to the app's icon and launcher.

Not in v0.4

• The command-line renderer isn't in the macOS disk image yet; build it from source.
• No Flatpak or AppImage; the Linux package is a .deb.
• The remaining Fractint gaps listed in the README: some types (bifurcation, lyapunov, plasma, icons3d), rotated views, Fractint's rand in formulas, and resuming unfinished orbit-plotting images.
• Screen-reader support.

FractalForge v0.3.0

FractalForge is a fast, modern fractal explorer for people who know Fractint and XFractint. It's an independent, clean-room GPL-3.0 implementation: it contains no Fractint source code.

v0.3 adds deep zoom, Fractint's 3D transforms and random-dot stereograms.

New in v0.3

• Deep zoom (mandel and julia). Zoom far past the limits of ordinary double precision. FractalForge keeps the view's centre to as many digits as it needs and renders by perturbation around one high-precision reference orbit.

  • In the app, zooming and panning keep full precision automatically. The View panel shows the precise centre, with a Copy centre button.
  • On the command line, --center-mag accepts a centre with any number of digits.
  • Deep views move both ways between FractalForge and XFractint at full precision, in GIFs and in PAR files.

• 3D transforms (Image > 3D Transform…). As in Fractint, the picture's colours become heights:

  • points, lines or surfaces, with rotation, scale, perspective and shift;
  • a light source with ambient light and smoothing;
  • projection onto a sphere;
  • red/cyan stereo pairs.

  The command line has fractalforge-cli 3d, which takes Fractint's keys (rotation=, filltype=, lightsource= …).

• Random-dot stereograms (Image > Stereogram…). Relax your eyes until the two bars become three. The command line has fractalforge-cli stereogram. You can set:

  • the depth effect and the picture width;
  • depth from brightness;
  • calibration bars;
  • a tiled pattern instead of random dots (command line only).

• Saving: both results can be saved as GIF (with Fractint's parameter block) or PNG.

How exact is it?

• Deep zoom: XFractint's deep images render to the same pixels at magnification 1e15 and 1e20. At 1e40, about 1% differ, because XFractint's own arbitrary precision is limited there.
• 3D transforms:
  • Most of Fractint's 3D test images are reproduced pixel for pixel.
  • Interpolated and light-source surfaces use a simplified colour rule, and with ambient light some colours are one palette index off.
  • Stereo pairs use FractalForge's own red/cyan palette.
• Stereograms are exact for the same random seed. Like Fractint, FractalForge seeds with the time, so each one is new.

The README lists the remaining differences, including Phase 4's chaotic orbit types.

Download

FractalForge-0.3.0-macos-universal.dmg runs on Apple silicon and Intel Macs with macOS 11 or later. Open the disk image and drag FractalForge to Applications.

This build isn't notarized by Apple, so the first time you open it macOS says it can't check it for malicious software. To open it anyway:

1. Try to open FractalForge once, and close the warning.
2. Open System Settings → Privacy & Security, scroll down, and click Open Anyway next to the FractalForge message.
3. Confirm with your password. After that it opens normally.

Or, in Terminal: xattr -dr com.apple.quarantine /Applications/FractalForge.app

The command-line renderer (fractalforge-cli) isn't in the disk image yet; build it from source. Linux and Windows builds aren't available yet, but FractalForge builds from source on both (see the README).

Not in v0.3

• Deep zoom for types other than mandel and julia, and with the inside/outside colouring options.
• Other Fractint types such as bifurcation, lyapunov, plasma and icons3d.
• Rotated and skewed views.
• Fractint's rand sequence in formulas.
• Resuming unfinished orbit-plotting, IFS and L-system images; they are calculated again, as Fractint does for most of them.
• Screen-reader support.

SHA-256 of FractalForge-0.3.0-macos-universal.dmg: 4de4070a96113e618af8a936cf12c2186745c571d1bb4c740bc135dae317035f

FractalForge v0.2.0

FractalForge is a fast, modern fractal explorer for people who know Fractint and XFractint. It's an independent, clean-room GPL-3.0 implementation: it contains no Fractint source code.

v0.2 adds Fractint-format formulas, L-systems, IFS and about two dozen orbit-plotting and strange-attractor types, plus an orbit window and a Mandelbrot/Julia toggle.

New in v0.2

• Formulas (.frm):
  • The Fractint formula language, with the same pixels as XFractint.
  • Supports symmetry qualifiers, fn1–fn4, the predefined variables, and formulas embedded in PAR files.
  • Syntax errors are reported with XFractint's error codes and line numbers.
• L-systems (.l): XFractint's file format, turtle commands and line drawing. Images match XFractint pixel for pixel.
• Iterated function systems (.ifs): 2D and 3D entries, drawn with the same random sequence as XFractint.
• Orbit-plotting types: henon, hopalong, martin, gingerbreadman, chip, quadruptwo, threeply, icons, latoocarfian, kamtorus, popcorn, popcornjul, dynamic, mandelcloud and julia_inverse.
• Strange attractors:
  • lorenz, lorenz3d, rossler3d, pickover, lorenz3d1, lorenz3d3, lorenz3d4 and kamtorus3d.
  • 3D rotation, shift and perspective, adjustable in the app.
• Orbit window (O): draws the orbit of the point under the pointer.
• Mandelbrot/Julia toggle (Space): switches to the Julia set at the pointer and back. Works for mandel/julia and six other type pairs.
• Files:
  • Opens .frm, .ifs and .l files.
  • Saved PAR files embed the formula, IFS or L-system, so they work on their own in FractalForge and XFractint.
  • GIFs FractalForge saves carry the entry's text, so they reopen without the original file.
• Command line: --formula, --ifs and --lsystem render entries from these files, and entries FILE lists a file's entries.

How exact is it?

Most types reproduce XFractint's images pixel for pixel; the test suite checks hundreds of XFractint reference images. A few chaotic orbit types (martin, chip, quadruptwo, threeply, latoocarfian, pickover and long lorenz3d1/3/4 orbits) draw the same attractors with different pixels. Their orbits depend on the last bit of the C library's or the processor's sine and cosine, which FractalForge doesn't copy. The README explains the remaining small differences.

Download

FractalForge-0.2.0-macos-universal.dmg runs on Apple silicon and Intel Macs with macOS 11 or later. Open the disk image and drag FractalForge to Applications.

This build isn't notarized by Apple, so the first time you open it macOS says it can't check it for malicious software. To open it anyway:

1. Try to open FractalForge once, and close the warning.
2. Open System Settings → Privacy & Security, scroll down, and click Open Anyway next to the FractalForge message.
3. Confirm with your password. After that it opens normally.

Or, in Terminal: xattr -dr com.apple.quarantine /Applications/FractalForge.app

The command-line renderer (fractalforge-cli) isn't in the disk image yet; build it from source. Linux and Windows builds aren't available yet, but FractalForge builds from source on both (see the README).

Not in v0.2

• Other Fractint types such as bifurcation, lyapunov, plasma and icons3d.
• Rotated and skewed views, deep zoom, 3D rendering of escape-time types.
• Fractint's rand sequence in formulas (FractalForge's rand is deterministic but different).
• Resuming unfinished orbit-plotting, IFS and L-system images; they are calculated again, as Fractint does for most of them.
• Screen-reader support.

SHA-256 of FractalForge-0.2.0-macos-universal.dmg: 6f5e0368c0b2b8b7666a09ef03905b15a0c48ea84555e833582a8b0226c8658e

FractalForge v0.1.0

FractalForge is a fast, modern fractal explorer for people who know Fractint and XFractint. It's an independent, clean-room GPL-3.0 implementation: it contains no Fractint source code. This is the first release.

What's in v0.1

• 17 escape-time fractal types: mandel, julia, lambda, mandellambda, mandel4, julia4, manowar, manowarj, barnsleym1, barnsleyj1, spider, magnet1m, magnet1j, newton, newtbasin, phoenix and mandphoenix. Their pixels match Fractint-format renderers for the same parameters.
• Colouring: inside and outside modes, decomposition and biomorph (for mandel and julia), colour cycling, built-in palettes and a palette editor.
• Stop and resume long renders. Save a render at any point as a GIF, then resume it later in FractalForge or XFractint. Partial renders XFractint saved can be resumed in FractalForge too.
• Fractint-format files: reads and writes PAR parameter files, MAP palettes and GIFs with parameter blocks.
• Desktop app:
  • Live progressive rendering, with scroll or pinch to zoom, drag to pan, and a zoom box.
  • Undo and redo, autosave, and PNG export.
• Command-line renderer (fractalforge-cli) for batch rendering and scripting. It isn't included in the disk image yet; build it from source.

Download

FractalForge-0.1.0-macos-universal.dmg runs on Apple silicon and Intel Macs with macOS 11 or later. Open the disk image and drag FractalForge to Applications.

This build isn't notarized by Apple, so the first time you open it macOS says it can't check it for malicious software. To open it anyway:

1. Try to open FractalForge once, and close the warning.
2. Open System Settings → Privacy & Security, scroll down, and click Open Anyway next to the FractalForge message.
3. Confirm with your password. After that it opens normally.

Or, in Terminal: xattr -dr com.apple.quarantine /Applications/FractalForge.app

Linux and Windows builds aren't available yet. FractalForge builds from source on both (see the README).

Not in v0.1

• Formula (.frm), L-system, IFS and other Fractint types. A PAR entry or GIF using them shows a clear message instead of rendering.
• inside=period and inside=startrail, and colouring options for types other than mandel and julia.
• Rotated and skewed views, deep zoom, 3D.
• Screen-reader support.
• When XFractint resumes one of FractalForge's partial renders, it finishes in one-pass mode.

SHA-256 of FractalForge-0.1.0-macos-universal.dmg: b3bc7b3852d604f9da45bf4734b08a3179b864247261667b4d527647985ac57a