grasses

//

// draw a sine wave, amplified

// program for lectures on "The Wrong Way to Draw a Line"

//

// turn the sin wave into random grass by 

// creating my own random and noise functions 

//

// schien@mail.ncku.edu.tw, DPD 2020

//

​

let xnoise = 0.0;

​

function setup() {

  createCanvas(500, 100);

  frameRate(12);

  //noLoop();

}

​

function draw() {

  background(255);

  strokeWeight(5);

  stroke(0, 30);

  line(20, 50, 480, 50);  // draw a line

​

  stroke(20, 50, 70, 180);

  let step = 10; 

  let lastx = -999; 

  let lasty = -999; 

  let y = 20; 

  let border = 70; 

  for (let x=border; x<=width-border; x+=step) { 

    let x1=x+20;

    let y1=y+20;

    strokeWeight(1);

    stroke(225,20,10);

    y = 50 - customRandom()*30;

    if (lastx > -999) { 

       line(x1, y1+20, x, 70); 

    } 

    lastx = x1; 

    lasty = y1; 

  } 

  for (let x=border; x<=width-border; x+=step) { 

    strokeWeight(1);

    stroke(225,20,80);

    y = 50 - customRandom()*30;

    let newx = x + customNoise()*step;

    line(x*2, y*2, x, y); 

    if (lastx > -999) { 

       line(newx, y, x, 50); 

    } 

    lastx = x; 

    lasty = y; 

  }

}

​

// my own random function

function customRandom() {   

   let retValue = 1 - pow(random(1), 5); 

   return retValue; 

}

​

function customNoise() {

  let rand = random(2) - 1;

  xnoise += rand;

  let retValue = noise(xnoise);

  return retValue;

}

​

function keyPressed() {

  if (key === 's' || key === 'S') {

    save('grasses.png');

  }

}