glslViewer Build Status


Live-coding console tool that renders GLSL Shaders. Every file you use (frag/vert shader, images and geometries) are watched for modification, so they can be updated on the fly.


Installing on Ubuntu

Install the GLFW 3 library and other dependencies:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install libglfw3-dev git-core

Download the glslViewer code, compile and install:

git clone
cd glslViewer
sudo make install

This was tested with Ubuntu 16.04.

These instructions may not work for all users. For example, it seems that libglfw3-dev conflicts with the older libglfw-dev. The previous Ubuntu install instructions direct you to download and compile glfw3 manually:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install git-core cmake xorg-dev libglu1-mesa-dev
cd ~
git clone
cd glfw
cmake .
sudo make install

Installing on Raspberry Pi

Get Raspbian, a Debian-based Linux distribution made for Raspberry Pi and then do:

sudo apt-get install glslviewer

Or, if you want to compile the code yourself:

cd ~
git clone
cd glslViewer
sudo make install

Installing on Arch Linux

sudo pacman -S glu glfw-x11
git clone
cd glslViewer
sudo make install

Or simply install the AUR package glslviewer-git with an AUR helper.

Installing on macOS

Use Homebrew to install glslViewer and its dependencies:

brew update
brew upgrade
brew install glslviewer

If you prefere to compile from source directly from this repository you need to install GLFW, pkg-config first and then download the code, compile and install.

brew update
brew upgrade
brew tap homebrew/versions
brew install glfw3 pkg-config
cd ~
git clone
cd glslViewer
make install

If glfw3 was installed before, after running the code above, remove glfw3 and try:

brew install glfw3 pkg-config
export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
make install


In the most simple scenario you just want to load a fragment shader. For that you need to:

cd examples
glslViewer test.frag
vim test.frag

Note: In RaspberryPi you can avoid taking over the screen by using the -l flags so you can see the console. Also you can edit the shader file through ssh/sftp.

Note: On Linux and macOS you may used to edit your shaders with Sublime Text 2, if thats your case you should try this Sublime Text 2 plugin that lunch glslViewer every time you open a shader.

Loading Vertex shaders and geometries

You can also load both fragments and vertex shaders. Of course modifing a vertex shader makes no sense unless you load an interesting geometry. That's why glslViewer is can load .ply files. Try doing:

glslViewer bunny.frag bunny.vert bunny.ply

Pre-Define uniforms and varyings

The following variables are used for fragment shaders that mimic a 3d model. See examples/menger.frag. Image Shaders image shaders are automatically detected and supported. These conventions are also supported by other tools, such as Synthclipse.

To be recognized as a ShaderToy image shader, a fragment shader must define ```c++ void mainImage(out vec4 fragColor, in vec2 fragCoord)

It must not define `main()`, because this is automatically defined for you.

The following ShaderToy uniforms are automatically defined,
you don't declare them:
* `uniform vec3 iResolution;` <br>
  `iResolution.xy` is the viewport size in pixels, like `u_resolution`.
  `iResolution.z` is hard coded to 1.0, just like and synthclipse,
  although it was originally supposed to be the pixel aspect ratio.
* `uniform float iGlobalTime;` <br>
  Shader playback time (in seconds), like `u_time`.
* `uniform float iTimeDelta;` <br>
  Render time for last frame (in seconds), like `u_delta`.
* `uniform vec4 iDate;` <br>
  [year, month (0-11), day of month (1-31), time of day (in seconds)],
  like `u_date`.
* `uniform vec4 iMouse;` <br>
  `iMouse` is initialized to 0, and only changes while the left mouse button
  (LMB) is being held down.
  * Mouse coordinates are integers in the range `[0,0]..iResolution.xy`.
  * `iMouse.xy` is the current mouse coordinates in pixels, while the LMB
    is being held down. When the LMB is released, `iMouse.xy` is set to the
    current coordinates, then stops changing.
  * `` is set to the current mouse coordinates at the instant when
    the LMB is pressed, remains constant as long as the LMB is held down,
    and is set to `` when the LMB is released.
  * If the LMB is up, then `iMouse.xy` is the mouse location at the most recent
    mouseup event, and `` is the negative of the mouse location at the
    most recent mousedown event.
    For example, after a mouse click, `iMouse` might be `[216,320,-216,-320]`.

Demo: `examples/numbers.frag`

### Textures

You can load PNGs and JPEGs images to a shader. They will be automatically loaded and asigned to an uniform name acording to the order they are pass as arguments: ex. `u_tex0`, `u_tex1`, etc. Also the resolution will be assigned to `vec2` uniform acording the texture uniforma name: ex. `u_tex0Resolution`, `u_tex1Resolution`, etc.

glslViewer test.frag test.png

In case you want to assign customs names to your textures uniforms you must specify the name with a flag before the texture file. For example to pass the following uniforms uniform sampled2D imageExample; and uniform vec2 imageExampleResolution; is defined in this way:

glslViewer shader.frag -imageExample image.png

Others arguments

Beside for texture uniforms other arguments can be add to glslViewer:

Inject other files

You can include other GLSL code using a traditional #include "file.glsl" macro. Note: included files are not under watch so changes will not take effect until the main file is save.

Console IN commands

Once glslViewer is running the CIN is listening for some commands, so you can pass data trough regular *nix pipes.


glslLoader is a python script that is install together with glslViewer binnary which let you download any shader made with The book of shaders editor ( . Just pass as argument the log number

glslLoader 170208142327

It will also download a shader shared through the ShaderToy's by passing the ID glslLoader. Ex:

glslLoader llVXRd


glslViewer examples/test.frag
glslViewer examples/test.frag examples/test.png
glslViewer examples/bunny.frag examples/bunny.vert examples/bunny.ply
glslViewer examples/grayscott.frag
glslViewer examples/platform.frag
glslViewer examples/temp.frag
examples/ | glslViewer examples/temp.frag
glslViewer examples/cross.frag --headless -s 1 -o cross.png
glslViewer examples/cross.frag --headless -s 1 -o cross.png
convert cross.png cross.pnm
potrace cross.pnm -s -o cross.svg
glslViewer examples/numbers.frag
glslLoader llVXRd
glslLoader 170208142327


Patricio Gonzalez Vivo: github | twitter | website


Thanks to:

Check the Git Repository