Extra parameter for animation

[viktak]

I was wondering how I could add an extra parameter to an animation. Here is an example:

void DoFade(const AnimationParam &param)
{
    RgbwColor updatedColor = RgbwColor::LinearBlend(
        animationState[param.index].StartingColor,
        animationState[param.index].EndingColor,
        param.progress);

    // apply the color to the strip
    strip.SetPixelColor(indexPixel, updatedColor);
}

Is there a way to parameterize indexPixel? Or is there another way to go about this?

Thanks for any pointers in advance! (Fantastic library, BTW!)

[Makuna]

what hardware platform are you using? With some you get modern c++ support for lambda functions. If you look at the example "NeoPixelAnimation", it demonstrates both models, without STL (like you list above using animationState), and with STL using lambda inline callback where the compiler captures any parameters for us.

Note that the example is just using the param.index to provide per pixel "parameters". If you don't need per pixel parameters, then animationState doesn't need to be an array, it can just be a struct.

the snippet from that example using lambda support ...

// we must supply a function that will define the animation, in this example
// we are using "lambda expression" to define the function inline, which gives
// us an easy way to "capture" the originalColor and targetColor for the call back.
//
// this function will get called back whenever the animation needs to change
// the state of the pixel, it will provide an animation progress value
// from 0.0 (start of animation) to 1.0 (end of animation)
//
// we use this progress value to define how we want to animate in this case
// we call RgbColor::LinearBlend which will return a color blended between
// the values given, by the amount passed, which is also a float value from 0.0-1.0.
// then we set the color.
//
// There is no need for the MyAnimationState struct as the compiler takes care
// of those details for us
AnimUpdateCallback animUpdate = [=](const AnimationParam& param)
{
    // progress will start at 0.0 and end at 1.0
    // we convert to the curve we want
    float progress = easing(param.progress);

    // use the curve value to apply to the animation
    RgbColor updatedColor = RgbColor::LinearBlend(originalColor, targetColor, progress);
    strip.SetPixelColor(pixel, updatedColor);
};

// now use the animation properties we just calculated and start the animation
// which will continue to run and call the update function until it completes
animations.StartAnimation(pixel, time, animUpdate);

Reviewing that example, all parameters must either be captured in the animationState global variable or automatically captured by lambda.

[viktak]

Thanks for the quick answer! I'm not sure if I understand it though... My platform is an ESP32-S3.
I'm gonna study your sample a bit more to understand how this works, but for the first look I still don't see how it takes the parameter. My case in point is that I have an animation I'd like to play on a set of, say, 4 pixels (each set is a different color). But those 4 pixels can change over time, and two animations can overlap. The issue was that if I started an animation (which worked fine), then if I start animating another set of LEDs with another color, the latter one messed up the first one.
Anyway, I'm gonna look at the sample and let you know if I managed to get it :)

[Makuna]

All ESP support lambda, so you should be able to use freely.

Use your favorite search engine and search "C++ lambda capture" for more details. Lambda's are worth learning, making some complex tasks to accomplish in C++ easier and cleaner. Note that some syntax sugar (even cleaner ways to use it) are provided by STL "functional" features, this is why it get included.

[viktak]

Yes, I haven't used lambda yet, I am looking into it now. Thanks for the explanation/pointers - more than I expected. Much appreciated!

[viktak]

Finally got it to work. Learnt lambdas on the way. Thanks again for your patience and again for this awesome library!!!!!