fractall

A portable fractal explorer written in C using SDL.

Features

• 24 fractal types: Von Koch, Dragon, Mandelbrot, Julia, Newton, Phoenix, Burning Ship, Tricorn, Mandelbulb, Buddhabrot, Lyapunov, Nebulabrot, and more
• 9 smooth color palettes: SmoothFire, SmoothOcean, SmoothForest, SmoothViolet, SmoothRainbow, SmoothSunset, SmoothPlasma, SmoothIce, SmoothCosmic
• Smooth coloring: Eliminates visible color bands using continuous iteration interpolation
• Interactive zoom: Click to zoom in/out, rectangular selection zoom for escape-time fractals
• Status bar: Displays fractal type, palette, iterations, zoom level, coordinates, and render time
• PNG export: Save screenshots with embedded fractal metadata
• Optional GMP support: High-precision arithmetic for deep zooms
• Performance optimizations: OpenMP multi-threading, SIMD (SSE4.1/AVX)

Building

./autogen.sh      # If configure doesn't exist
./configure
make
./src/fractall

Configure Options

Option	Description	Default
--with-gmp	Enable high-precision arithmetic	enabled
--disable-openmp	Disable parallel computation	enabled
--disable-simd	Disable SIMD (SSE4.1/AVX)	enabled
--with-png	Enable PNG export with metadata	enabled

Dependencies

• SDL 1.2.0+
• Standard math library (-lm)
• GMP (optional): High-precision arithmetic for deep zooms
• OpenMP (optional): Multi-threaded rendering
• libpng (optional): PNG export with metadata

Usage

fractall [OPTIONS]

Option	Description	Default
-x<n>	Window width	800
-y<n>	Window height	600
-f	Fullscreen mode	-
-g<n>	GUI height	51
-nogui	Disable GUI	-
-h	Show help	-

Controls

Key/Action	Effect
F1-F12	Select fractal types 1-12
GUI buttons	Select any of the 24 fractal types
C	Cycle color palette (9 palettes)
R	Cycle gradient repetition (2-40, step 2)
S	Screenshot (PNG with metadata)
Q / ESC	Quit
Left click	Zoom in / +1 iteration (vector fractals)
Left click + drag	Rectangular selection zoom (escape-time)
Right click	Zoom out / -1 iteration (vector fractals)

Fractal Types

Vector Fractals (Types 1-2)

• Von Koch - Snowflake fractal (max 8 iterations)
• Dragon - Dragon curve (max 20 iterations)

Escape-Time Fractals (Types 3-24)

• Mandelbrot - The classic z = z² + c
• Julia - Julia set with configurable seed
• Julia Sin - z = c × sin(z)
• Newton - Newton's method fractal
• Phoenix - Phoenix fractal
• Buffalo - |Re(z²)| + i|Im(z²)| + c
• Barnsley J/M - Barnsley fractal variants
• Magnet J/M - Magnetic fractal variants
• Burning Ship - Uses absolute values
• Tricorn - Uses complex conjugate
• Mandelbulb - 2D slice of 3D fractal (power 8)
• Buddhabrot - Density-based rendering of escape trajectories
• Lyapunov Zircon City - Lyapunov exponent (sequence "BBBBBBAAAAAA")
• Perpendicular Burning Ship, Celtic, Alpha Mandelbrot
• Pickover Stalks, Nova, Multibrot, Nebulabrot

Color Palettes

#	Palette	Gradient
0	SmoothFire	Black → Red → Yellow → White
1	SmoothOcean	Black → Blue → Cyan → White
2	SmoothForest	Black → Green → Yellow → White
3	SmoothViolet	Black → Violet → Pink → White
4	SmoothRainbow	Full rainbow spectrum
5	SmoothSunset	Black → Orange → Red → Violet → Blue
6	SmoothPlasma	Blue → Violet → Pink → Orange (default)
7	SmoothIce	White → Cyan → Blue → Black
8	SmoothCosmic	Black → Blue → Turquoise → Yellow → Orange → Red

All palettes use continuous iteration interpolation to eliminate visible color banding. Gradient repetition adjustable with R key (default: 40).

Screenshots

Press S to save the current fractal as PNG with embedded metadata (type, coordinates, iterations, palette, etc.).

Changelog

• 1.0 (2026) - Major rewrite: 24 fractal types, 9 palettes, PNG export, OpenMP/SIMD optimizations, optimized Lyapunov calculation
• 0.5.1 (2025) - Added smooth coloring, status bar, bug fixes
• 0.5 (2003) - Initial release

Author

Arnaud VERHILLE (2001-2026)