let numMovers = 1;

​

let liquidBoundary = 0;

//https://sciencenotes.org/table-of-density-of-common-materials/

let airRho = 0.001;

let liquidRho = airRho * 1000; //(water is about 1000 times more dense than air)

let sandRho = liquidRho * 10000;

​

//multiply v every round. TODO: Move this into drag function.

//energy lost due to drag=𝐅𝐝𝐫𝐚𝐠⋅displacement which is volume.

let energyDissapationAir = 1.0;

let energyDissapationLiquid = 1.0;

let energyDissapationTransition = 1.0;

let energyDissapationSand = 1.0;

​

// let energyDissapationAir = airRho;

// let energyDissapationLiquid = airRho;

// let energyDissapationTransition = airRho;

// let energyDissapationSand = airRho;

​

​

function setup() {

  frameRate(12);

  //let color1 = color(204, 204, 0, 255);

  let color2 = color(0, 204, 204, 255);

  //let color3 = color(204);

  createControlledCanvas(400, 400);

  liquidBoundary = width/2;

  background(51);

  let gravity = createVector(0,9.8);

  for (let i = 0; i < numMovers; i++) {

    movers[i] = new Mover(random(0, width), 0, random(0.1,0.8), color2, gravity);

  }

}

​

function draw() {

  if (runFlag) {

    let color1 = color(204, 204, 0, 255);

    let color2 = color(0, 204, 204, 255);

    let color3 = color(204);

​

    let wind = createVector(0.5,0);

​

    background(51);

​

    stroke(color3);

    line(0, liquidBoundary, width,liquidBoundary);

​

    let windIsBlowing = false;

    if (mouseIsPressed) {

      windIsBlowing = true;

    }

​

    movers.forEach(mover => {

      let radius = mover.diameter/2;

      let tmin = liquidBoundary-radius;

      let tmax = liquidBoundary+radius;

​

​

      mover.applyGravity();

​

      //Is just even barely touching the sand put on the brakes, because I'm too

      //lazy to transition.

      if (mover.pos.y > height-(radius)) {

        mover.color = color2;

​

        mover.dissipate(energyDissapationSand);

        mover.applyDrag(sandRho);

​

        mover.applyReverseGravity(); //<-- this is a bit of a cheat.

        //console.log("sand:", mover.velocity.y)

      }

      //fully in the liquid.

      else if (mover.pos.y > tmax) {

        mover.color = color3;

        //energy dissipates in sound, etc. TODO RealEQ

        //rain drops do bounce on the surface, etc.

        mover.dissipate(energyDissapationLiquid);

        mover.applyDrag(liquidRho);

        //console.log("liquid:", mover.velocity.y)

      }

      //an attempt to play around with a transition

      else if (mover.pos.y >= tmin && mover.pos.y <= tmax) {

        mover.color = color(204, 102, 0);

​

        //it is correct that there is a transition, but this is not the right math.

        //I'm doing it by percentage of h

        //but it should be an integration over the surface area/delta-volume.

        //Also the decrease in acceleration needs to be dissapated? Will that come for free?

        let liquidPercent = (mover.pos.y - tmin)/mover.diameter;

        let airPercent = 1-liquidPercent; //this should never be negative.

​

        if (airPercent < 0) {

          log.console("something's gone wrong, airPercent is negative")

        }

​

        let drag = airPercent*airRho + liquidPercent*liquidRho;

​

        mover.dissipate(energyDissapationTransition);

        mover.applyDrag(drag);

        //console.log("transistion:", mover.velocity.y, airPercent, drag)

      }

      //default air.

      else {

        //console.log("air:", mover.velocity.y)

        mover.color = color1;

​

        mover.dissipate(energyDissapationAir);

        mover.applyDrag(airRho);

      }

​

      mover.update();

      mover.render();

    });

​

  }

}

​