[ANSWERED] Footprints following a performer randomly walking on a stage

mark_m

Greetings all,

Working on a show on a circular stage with IR tracking from an overhead camera following performers equipped with IR emitters via Eyes ++
We have projectors projecting downwards onto the stage.

Using the 3D Particles actor to create the footprints.

Three questions:

1. Which is the best method for taking the XY values from the Blob Decoder and using them to place the footprints on the stage behind the moving performer?

2. If the performer were to walk in a circle, how to I get the angle of the footprints to change with the orientation of the performer? Is it even possible?

3. If the performer were to start running, how can I increase the frequency of the footprints?

@bonemap Russell, you must have done this sort of thing... any online documentation of how you've done it?

All help gratefully receieved, as ever!

Cheers

Mark in Sunny Wales run off with the Circus. Again.

DusX

@mark_m

#1: unsure what your looking for here.. maybe use some type of delay line?

#2: Using a little trig. If you have the current XY, and you have the past XY via a delay line, you can calculate the rotation.

#3: Using the same current and past XY, you can use the Velocity actor to watch speed and adjust as needed.

I am attaching some JS I use to get angles between 2 XY points.

// input1: X of rotating thing (Izzy range -50 to 50)
// input2: Y of rotating thing (Izzy range -50 to 50)
// input3: X of focus item eg: mouse (Izzy range -50 to 50)
// input4: Y of focus item eg: mouse (Izzy range -50 to 50)
// input5: stage width (pixels)
// input6: stage height (pixels)
function rotate(focusX,focusY,selfX,selfY,wPercent){
  //distance of focus from self
  var dx = focusX - selfX;
  var dy = focusY - selfY
  debug("vars. dx: " + dx  + " dy: " + dy + " wPercent: " + wPercent + "\n");
  return (Math.atan2( (dy * wPercent) , (dx) ) );
}
function rad2deg(rad){
  return rad * (180 / Math.PI);
}
function debug(printString){
    if (DebugMode){
        print(printString + "\n");
    }
}
function main(){
  // DO setup here: ONCE ONLY ************************************************
    DebugMode = false; //example usage: debug("string" + var + "\n");
    // main function for LOOP **************************************************
    main = function(){
      // get focus XY from Izzy enviroment
        var focusX = arguments[2]; // reverse due to flipped X in Izzy
        var focusY = arguments[3]; // reverse due to flipped Y in Izzy
      // get current Self Position
        var selfX = arguments[0]; // center for now
        var selfY = arguments[1]; // center for now
      // used to normalize the w/h at 100%
        var wPercent = arguments[5] / arguments[4];
      debug("vars. mX: " + focusX  + " mY: " + focusY + " sX: " + selfX + " sY: " + selfY + "\n");
          return [ rad2deg( rotate(focusX,focusY,selfX,selfY,wPercent) ) * -1]; // *-1 added to rotate other direction
    };
    // RUN ONCE FOR INIT ONLY
    var out = []; // declare out
    return out; // return from INIT state
}

and the JS being used.

bonemap

@mark_m said:

you must have done this sort of thing...

Hi,

I do have something that I think will get you started... it is using the same principles suggested by @DusX, but packaged up in a demonstration patch.

blob-particle-follow.zip

Best Wishes

Russell

mark_m

@bonemap @DusX

Great, thank you so much! Those are the very things! I'm so grateful!

Cheers

Mark

DusX

@mark_m

I think you will also what to use Pythagoras to calculate the distance between your 2 reference points, so that you don't update the rotation unless the distance is greater than a set threshold.
Bonemaps example is great, but if you stop moving the mouse you get some unwanted rotation changes with any small point updates.

bonemap

@dusx

Hi,

The javascript solution does efficiently resolve the issue of what happens when the movement stops. I have so much to learn - Thanks for sharing it!

@mark_m here is a screengrab how I was able to integrate @DusX javascript. Apologies done with a beta version so I can't share the patch file.

Best Wishes

Russell

mark_m

@bonemap

Thanks a lot! Will try that..

Meanwhile, demonstrating that you can do anything many ways in Isadora... we used your (@bonemap's) original patch, and connected the 2D velocity actor to the blob tracker's X and Y output, and connected that to the pulse generator of the 3D Particle Generator. So that if the velocity was zero, no footsteps (particles) were emitted, and the faster you ran, the more footsteps got laid down.

We also used the technique that you shared with us a while ago in your excellent tutorial on sprite animation to make left and right footprints!

Here's a screen grab of this scene (the blob tracking itself is done in a secondary scene: the listeners get the x / y positions:

And the video of our first, crude attempts: a quick demo to the director to show we were on the right track (no pun intended!).

We'll get back to that and give it a go with the Javascript as well.

Thanks Russell and Ryan, you're both marvellous!

DusX

@bonemap said:

@dusxHi,The javascript solution does efficiently resolve the issue of what happens when the movement stops. I have so much to learn - Thanks for sharing it! @mark_m here is a screengrab how I was able to integrate @DusX javascript. Apologies done with a beta version so I can't share the patch file.<img src="/assets/uploads/files/1634079469460-screen-shot-2021-10-13-at-8.50.35-am.png" />Best WishesRussell

Nice approach!