glslp

• GLSL: Shader format available to OpenGL. Wide range of platforms including phones and tablets.

https://retropie.org.uk/forum/topic/31960/video_shader_watch_files-on

https://forums.libretro.com/t/watch-shaders/36188

• .glslp for GLSL stack these shaders to create a combined effect. These complex effects are saved with a special extension.

So maybe glslp is not a shader at all?