ShaderTool

Live tool for developing OpenGL shaders interactively.

I developed this small program to experiment with shaders locally, to reproduce an experience like Shadertoy offline, with the ability to choose my own text editor. It was also a good project to learn OpenGL development. For this reason, the code is very minimal and should be fairly readable.

Additional features:

• Extensive logging (using the nice log.c library)
• FPS tracking
• Reload shaders automatically on save (using inotify)
• Save screenshot to a file
• Complete argument parsing with Argp
• Full documentation with Doxygen

Build

This project requires the GLFW, GLEW, and FreeImage libraries. On a Debian/Ubuntu system:

sudo apt-get install libglfw3-dev libglew-dev libfreeimage-dev

To build (with Meson):

meson build
ninja -C build

To build the documentation with Doxygen:

doxygen Doxyfile

The documentation is also available online.

Usage

Usage: shadertool [OPTION...] SHADER
                                    Compile and render the SHADER.
ShaderTool -- Live tool for developing OpenGL shaders interactively

  -b, --buffer=FILE          Source file of the buffer fragment shader
  -r, --auto-reload          Automatically reload on save
  -s, -q, --silent, --quiet  Don't produce any output
  -v, --verbose              Produce verbose output
  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version

For instance, to run the mandelbrot shader with live reloading on save:

shadertool -r shaders/mandelbrot.frag

Keyboard shortcuts:

• Escape to quit
• R to reload the shaders
• S to save a screenshot to the current directory, in a file shadername_frame_date_time.png

Limitations

For now, the "buffer" shader (i.e. the additional shader that renders in a texture in another framebuffer) does not work properly. I don't understand exactly what's broken, but maybe I'll investigate it more closely later. If you have any idea about what went wrong, don't hesitate to notify me!

References and other resources

• LearnOpenGL
• open.gl
• docs.gl
• The Book of Shaders
• glslViewer, a much more complete project with similar aims
• Shadertoy
• smoothstep.io
• webgl-noise, a collection of reference implementations of noise functions, for use in shaders