ups, this was an copy&past error. I wouldn't copy my recalbox.conf and I added the wrong file into the zip. add this to your recalbox.conf at the end:
# ------------ S - SHADERS ----------- #
##Sample: <emu>_shader=<presetfile>.glslp
##
gb_shader=dot-green.glslp
mastersystem_shader=dot.glslp
It's generally activated on all retroarch/libretro emus within emulationlaucher.sh. In /recalbox/scripts/emulatorlaunch.sh I have enable_shader="$essetting get EnableShader" enable_shader=„true" you need to delete this line with (enable_shader=„true") as soon as the optionssetting via emulationstation is ready. The logic for loading the shaders is now like this: - First it looks if shaders are enabled. - Second it look if a shader for this emulator in recalbox.conf is configured -> shaders/<emulator>/<file>.glslp - Third it looks in shaders/_presets/ if there is a <emulator>_default.glslp - Last but not least it will load when nothing is there default.glslp in shaders/_presets - When Shaders are desibled I do set the video_shader_dir, so the user has the ability to activate the shader via RGUI.