rpi_ws281x | Userspace Raspberry Pi PWM library for WS281X LEDs

Docker has the concept of a "build context". That defines the directory from which files are accessed. So when you say COPY foo /foo in your Dockerfile, that's copying the foo file from the build context and places it in the root folder of your container with the name foo. You set the build context when running the docker build command. Very often, people use . as the build context which means the current working directory that you're running the command from (e.g. docker build -t app .). So it depends on what directory your build context is. That's where you should be placing the .SO library so that you can then add a COPY instruction in your Dockerfile to copy it into your container image.

In your second example, try ws2811_channel_t channel{}; and ws2811_t test{}; - e.g. add the {}.

If you do this, then you'll zero initialise all the members. The key difference between your first (working) version, and the second (broken) version is that first version will zero things like gamma whilst the second version won't. Adding {} will zero everything before you overwrite the items you want.

If you do type a = {...}, then whatever is in the ... and not mentioned or indexed will be zeroed. If you do type b; b.field=value; there is nothing here that will zero any specifically not initialised fields.

@Clifford MakeWS2811(...) does take a pointer, but it looks like it makes a copy of the options in C.

However the returned instance has a Leds(nChannel) method, giving direct access to set the colours of LEDs. You can reduce the colour value to reduce the brightness (approximately).

To get it to update continuously you will need to modify the TempTask class so its update_temp() method contains a loop, and also add a Lock to it to control concurrent access to the ir_temp attribute to allow it to safely be accessed by more than one thread.

Note, that it's not clear if the Lock is really needed, since you do nothing but read the TempTask instance's attribute in the main thread — but the loop in the update_temp() method is needed to keep running the irCounter() function. You also might want to change the while True: to reference another (additional) instance attribute that control whether it is to keep running or not.

Additional note:

It's unclear why you have the while True: loop in irCounter(), because it has as return near the end that prevents it from ever iterating more than once. Doing so isn't crucial, but I recommend that you remove it.

I went and looked at the repo you are trying to build. This SConstruct looks like it expects some TOOLCHAIN variable to be passed to it: