Already running OpenRGB? Where a shader file goes for the Effects plugin and for the AI Shader plugin, why a file you just added is missing from the dropdown, and the uniforms a shader is allowed to read.
Effects plugin: <OpenRGB config>/plugins/settings/effect-shaders/. AI Shader plugin: <OpenRGB config>/plugins/settings/ai-shader-shaders/.
<OpenRGB config>/plugins/settings/effect-shaders/
<OpenRGB config>/plugins/settings/ai-shader-shaders/
The Effects plugin builds its shader list when the effect is created, so restart OpenRGB after adding a file.