Deprecate and remove ws2812 effects (and provide an in-Lua replacement)

[nwf]

There is no reason whatsoever that this module should be in C; timers and ws2812 frame buffers are easily managed from Lua. Worse, its existence complicates implementing #2916, which is obviously a good idea for the health of the entire tree.

If it were up to me, I'd just rip it out wholesale right now. But I recognize it's not, so I wonder if someone who cares about the module would like to write Lua equivalents of each of its effects for inclusion in lua_examples.

If it turns out that there are operations that cannot be easily achieved from Lua, then we should augment the buffer interface until that's not true, and I would gladly add such things to my nascent #2916 implementation.

[HHHartmann]

The ws2812_effects module consists of two main functionalities which are interwoven and should be separated.

1. the player, which repeatedly updates the LED strip with the newly calculated effect.
2. the effects themselves.

So there should be a player and separate effects which can be passed to the player.
It should also support all (3 I think) different Led Modules.
The effects should probably have an interface consisting of init(params) and next_buffer next_step(old_buffer) to calculate the next step.

Originally I was planning to adapt the module also, but I agree that both should be doable in Lua.

Should we sneak in a deprecation warning in the module then before the release?

@marcelstoer Do you have statistics of the usage in the cloud builder of this module?

[nwf]

@HHHartmann Sneaking a deprecation warning seems like a good plan to me. Since we don't have a replacement module ready, point at this issue?

FWIW, I've been mocking up a proposal for lua_examples that I'll push in just a moment. You are more than welcome to take it and mutate it to your heart's desire. :)

[HHHartmann]

I have been thinking about this. It certainly would be good to allow individual effects in Lua but on the other hand executing some effects that change many pixels individually will take around factor 100 longer to execute in Lua than in C. But then, looking at the existing effects at most the flickering effects modify several pixels, but not that many, so that might be neglected.

[nwf]

If there are bulk editing combinators that would be useful to have in C, we should add them to pixbuf. I'm not opposed to a "miscellaneous special purpose pixbuf functions" module, either (pixbuf.morefun?) if it's necessary. I mostly want the timer callbacks and pixbuf references handled in Lua and not in C. Actual math that's gotta go fast can, of course, remain in C.

Failing any of that, I'd still move to merge #3158 if someone can test that ws2812_effects still works with it.

[skycoders]

@nwf @HHHartmann Just noticing this topic: I originally implemented the effects library. Unfortunately there is no time to work on it right now, so fine with anything you do to bring the overall led support forward. Reason for the C implementation is that the performance in lua on the 8266 has been unacceptable. I initially implemented this in user code, but the array operations and copying them down to the buffer would not allow smooth animations. This should be considered when changing the implementation. I ran that on 300px strips. If you need someone to test a new implementation, let me know.

[nwf]

@skycoders Hi!

I suspect what we will find is that there are transforms we want to add to pixbuf (nee ws2812.buffer) to make it a suitable substrate to replace the effects library, so that performance remains acceptable, but I have not spent time looking at exactly what those would be. New day job 'n all that. Anyway, I'm hopeful that a fairly straightforward set of bitblitting primitives beyond what we already have would go a long way.

I don't happen to have any 300px strips, but that shouldn't stop us from using a 300 pixel buffer for testing.

When I or, more likely, @HHHartmann have a concrete proposal, we'll be sure to ask; thanks for offering! :)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[marcelstoer]

I am reopening this as https://nodemcu.readthedocs.io/en/release/modules/ws2812-effects/ points here.