Chained - script.js

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// Chained
// @afrosquared | Ben Ursu
// Instagram | Spark AR Studio | SDK v62.0
// https://www.instagram.com/a/r/?effect_id=296042214483846



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//require

const Scene = require('Scene');
const Animation = require('Animation');
const R = require('Reactive');
const D = require('Diagnostics');
const Time = require('Time');
const Materials = require('Materials');
const Textures = require('Textures');
const TouchGestures = require('TouchGestures');
const FT = require('FaceTracking');



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//init

var zero = Scene.root.find('zero');
var rotation180 = Math.PI;
var rotation360 = Math.PI * 2;
var vectorForward = R.vector(1, 0, 0);

var facetracker0 = Scene.root.find('facetracker0');
var facePosition = FT.face(0).forehead.top;
var connection0 = Scene.root.find('connection0');
var connection1 = Scene.root.find('connection1');



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//segments

var segmentStreakTotal = 1;
var segmentSegmentTotal = 30;

var positions = [];
var segments = [];
var segmentLines = [];
var segmentLineCubes = [];
var segmentPositionRatios = [];
var segmentScaleRatios = [];
var segment0Connect = Scene.root.find('segment0_connect');

for(var i = 0; i <= segmentStreakTotal; i++){
  positions.push([]);
  segments.push([]);
  segmentLines.push([]);
  segmentLineCubes.push([]);
  segmentPositionRatios.push([]);
  segmentScaleRatios.push([]);
}

for(var i = 0; i < segmentStreakTotal; i++){

  for(var k = 0; k < segmentSegmentTotal; k++){

    var segment = Scene.root.find('segment' + i + '_' + k);
    segment.hidden = false;
    var segmentLine = segment.child('line');
    var segmentLineCube = segmentLine.child('cube');
    var segmentLineCubeNode = segmentLineCube.child('node-0');
    segmentLineCubeNode.transform.scaleX = 0.0014;
    segmentLineCubeNode.transform.scaleZ = 0.0014;
    var segmentPositionRatio = R.val(1);
    var segmentScaleRatio = R.val(1);
    segments[i].push(segment);
    segmentLines[i].push(segmentLine);
    segmentLineCubes[i].push(segmentLineCube);
    segmentPositionRatios[i].push(segmentPositionRatio);
    segmentScaleRatios[i].push(segmentScaleRatio);

  }

  for(var k = 0; k <= segmentSegmentTotal; k++){
    var position = Scene.root.find('position' + i + '_' + k);
    positions[i].push(position);
  }

}



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//segments lookat

for(var i = 0; i < segmentStreakTotal; i++){

  for(var k = 0; k < segmentSegmentTotal; k++){

    segments[i][k].transform.position = positions[i][k].transform.position.mul(segmentPositionRatios[i][k]);
    segmentLineCubes[i][k].transform.scaleX = positions[i][k].transform.position.distance(positions[i][k+1].transform.position).mul(segmentScaleRatios[i][k]);

    var position0_forwardVector = R.normalize(positions[i][k+1].transform.position.sub(positions[i][k].transform.position));
    var position0_rotationAxis = position0_forwardVector.cross(vectorForward);
    var position0_dot = position0_forwardVector.dot(vectorForward).add(1);

    var position0_w0 = position0_dot.mul(-1);
    var position0_x0 = position0_rotationAxis.x;
    var position0_y0 = position0_rotationAxis.y;
    var position0_z0 = position0_rotationAxis.z;

    var position0QuatL = R.sqrt((position0_x0.mul(position0_x0)).add(position0_y0.mul(position0_y0)).add(position0_z0.mul(position0_z0)).add(position0_w0.mul(position0_w0)));
    var position0QuatLL = R.val(1).div(position0QuatL);

    var position0_w = position0_w0.mul(position0QuatLL);
    var position0_x = position0_x0.mul(position0QuatLL);
    var position0_y = position0_y0.mul(position0QuatLL);
    var position0_z = position0_z0.mul(position0QuatLL);

    //quaternion to euler using zyx
    var position0_r11 = R.val(2).mul((position0_x.mul(position0_y).add(position0_w.mul(position0_z))));
    var position0_r12 = (position0_w.mul(position0_w)).add(position0_x.mul(position0_x)).sub(position0_y.mul(position0_y)).sub(position0_z.mul(position0_z));
    var position0_r21 = R.val(-2).mul((position0_x.mul(position0_z)).sub(position0_w.mul(position0_y)));
    var position0_r31 = R.val(2).mul((position0_y.mul(position0_z)).add(position0_w.mul(position0_x)));
    var position0_r32 = (position0_w.mul(position0_w)).sub(position0_x.mul(position0_x)).sub(position0_y.mul(position0_y)).add(position0_z.mul(position0_z));

    var position0_heading = R.atan2(position0_r31, position0_r32);
    var position0_asin_attitude = R.asin(position0_r21);
    var position0_bank = R.atan2(position0_r11, position0_r12);

    segments[i][k].transform.rotationX = position0_heading;
    segments[i][k].transform.rotationY = position0_asin_attitude;
    segments[i][k].transform.rotationZ = position0_bank;

    if(i == 0 && k == 0){
      segment0Connect.transform.position = segments[i][k].transform.position;
      segment0Connect.transform.rotationX = segments[i][k].transform.rotationX;
      segment0Connect.transform.rotationY = segments[i][k].transform.rotationY;
      segment0Connect.transform.rotationZ = segments[i][k].transform.rotationZ;
    }

  }

}



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//segments start/end positions

function segmentPositions(){

  var faceZOffset = 53.5;
  var segmentXDirection = 0.025;
  var segmentXOffset = 0;
  var segmentYLength = 1;
  var segmentZLength = 1;

  for(var i = 0; i < segmentStreakTotal; i++){

    for(var k = 0; k <= segmentSegmentTotal; k++){

        var percentage = k/segmentSegmentTotal;

        var bridgeToConnection0AttractionPerc = percentage;

        var bridgeToConnection1AttractionPerc = R.vector(bridgeToConnection0AttractionPerc * bridgeToConnection0AttractionPerc, 0, bridgeToConnection0AttractionPerc * bridgeToConnection0AttractionPerc);
        if(k == segmentSegmentTotal){
          bridgeToConnection1AttractionPerc = 0;
        }

        var bridge = FT.face(0).cameraTransform.applyTo(facePosition.add(R.vector(segmentXOffset + (segmentXDirection * (k*k)), (Math.sin(Math.PI * percentage))*segmentYLength, k*segmentZLength))).add(R.vector(0,0,faceZOffset));

        var bridgeToConnection0 = connection0.transform.position.sub(bridge);
        var bridgeToConnection0Weight = bridge.add(bridgeToConnection0.mul(bridgeToConnection0AttractionPerc));

        var bridgeToConnection1 = connection1.transform.position.sub(bridgeToConnection0Weight);
        var bridgeToConnection1Weight = bridgeToConnection0Weight.add(bridgeToConnection1.mul(bridgeToConnection1AttractionPerc));

        positions[i][k].transform.position = bridgeToConnection1Weight;

    }

  }

}
segmentPositions();



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// helplers

function getRandom(min, max) {
  return Math.random() * (max - min) + min;
}