Project-09-Portrait

//jiaqiwa2; Jiaqi Wang; Section C
var portrait;
//I learned & referenced how to make a moving sin wave from this example:
//https://p5js.org/examples/math-sine-wave.html
let xspacing = 5; // Distance between each horizontal location
let w; // Width of entire wave
let theta = 0.0; // Start angle at 0
let amplitude = 20.0; // Height of wave
let period = 700.0; // How many pixels before the wave repeats
let dx; // Value for incrementing x
let yvalues; // Using an array to store height values for the wave
var num=8;

function preload(){

	portrait=loadImage("https://i.imgur.com/J6Im42B.jpg");
}


function setup() {
  createCanvas(460,400);   
  w = width + 16;
  dx = (TWO_PI / period) * xspacing;
  yvalues = new Array(floor(w / xspacing));
  frameRate(10);
    
}



function draw() {
  //image(portrait,0,0,460,400);
  background(250);
 //gradually "open" the portrait
 if(num<40){
   num+=0.5;
  }

 for(var i=0;i<num;i++){
 	var yUpper;
  var yLower;
  
  yUpper=height/2-i*5;
  yLower=height/2+i*5;
  amplitude+=1;
  if(amplitude>40){
    amplitude-=1;
  }  

  calcWave();
  renderWave(yUpper);
  renderWave(yLower);


  
  
    }
  
}

function calcWave() {
  // Increment theta (try different values for
  // 'angular velocity' here)
  theta += 0.02;

  // For every x value, calculate a y value with sine function
  let x = theta;
  for (let i = 0; i < yvalues.length; i++) {
    yvalues[i] = sin(x) * amplitude;
    x += dx;
  }
  
}


function renderWave(Start) {
  noStroke();
  
  // draw the wave with an ellipse at each location
  for (let x = 0; x < yvalues.length; x++) {
  	//y postition of the ellipse
  	var y=Start + yvalues[x];
  	//x position of the ellipse
  	var X=x * xspacing;
  	//find the corresponding pixel's location on my portriat
  	var Px=map(X,0,460,0,portrait.width);
    var Py=map(y,0,400,0,portrait.height);
    //check if this pixel is within the canvas.
    if(y>0 & y<400){
    	let pix = portrait.get(Px, Py);
        fill(pix);
        ellipse(X, y, 7, 7);

    }
    
  }
}