The SRE GLSL Editor allows you to play with shaders without having to set up everything in OpenGL. The editor is build using SimpleRenderEngine (https://github.com/mortennobel/SimpleRenderEngine)
First fork and clone the library (git clone --recurse-submodules <url>).
An interactive html demo is available. Note that the html demo has some limitation compared to the desktop version (no copy-past and no file access).
