GPU Fractals

This repository contains some sample code for generating fractals by taking advantage of GPU computing power given by the OpenGL compute shaders.
The application in the repository can produce, at the moment, the following fractals:

• Newton's fractals
• Mandelbrot's set
• Julia's set

Requirements

In order to compile and run the application you need the following external libraries:

• GLAD
• GLFW
• STB Image
• STB Image Write

Libraries are provided inside the ext folder, but the CMake script allows for user-provided implementations. The user can provide its own implementation by changing one or more of the following CMake variables:

• GLAD_HOME
• GLFW3_HOME
• STB_HOME

⚠️WARNING: The GLFW3 folder must contain a sub-path lib/cmake/glfw3 with the CMake scripts for finding the GLFW3 package.

Additional notes for STB

The header library STB provides the implementation of the functions only when the files are included after the definition of the following macros:

#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION

A file with these macros defined is included in the ext folder, so don't change it in the CMakeLists.txt file.

Usage

Compile

The application is build using CMake. Create a build directory inside the repository, configure the CMake project and build.
During the building process it is possible to select the size of the exported texture or the directories containing the user-defined implementations of the libraries. By default, libraries are provided in the ext and textures are 4096 X 4096.

    cd build
    cmake .. [-DTEX_SIZE=<Value>] [-D<libname>_HOME]
    cmake --build .

⚠️WARNING: At the moment, if TEX_SIZE is set manually and you want then to use the default value, you have to either pass it manually, delete the variable from cache or delete the cache.

Run

The syntax to run the application is the following:

    ./GPUFractals <TYPE> [ OPTIONS ]

Where TYPE can be one in Newton, Mandelbrot and Julia (case-insensitive). The optional arguments depend on the type of fractal.

• Mandelbrot does not have additional options.
• Newton can define the number of roots of the polynomial. If no argument is given, default is 3.
• Julia set is computed with the recurrence z = z^2 + 0.7885 * exp(i * a). The optional argument is the value of a. If no argument is given, default is pi / 2.

Inside the application the following commands can be used:

• Moving the mouse during a left click will translate the plane along the X and/or Y axis.
• Moving the mouse during a right click will scale the plane.
• Pressing +/- will increase/decrease the number of iterations (Newton) or the granularity of the colormap (Mandelbrot/Julia). Increment is by 1.
• Holding Shift while pressing +/- makes the increment in steps of 10.
• Pressing E will export the view to the current working directory.
• Pressing ESC will close the application.