Arrays & Objects

Store collections of data with arrays and objects.

Arrays

Arrays hold lists of values:

fn setup() {
  size(300, 200)
}

fn draw() {
  background(rgb(30, 30, 40))

  let colors = [coral, cyan, yellow, purple, green]

  for i in 0..len(colors) {
    fill(colors[i])
    circle(40 + i * 55, 100, 25)
  }
}

Adding to Arrays

Use push(array, value) to add items:

let particles = []

fn setup() {
  size(300, 200)
}

fn draw() {
  background(rgb(30, 30, 40))

  // Add particle on click
  if mousePressed {
    push(particles, {
      x: mouseX,
      y: mouseY,
      vx: random(-2, 2),
      vy: random(-3, -1)
    })
  }

  // Update and draw particles
  for i in 0..len(particles) {
    let p = particles[i]
    p.x = p.x + p.vx
    p.y = p.y + p.vy
    p.vy = p.vy + 0.1

    fill(coral)
    circle(p.x, p.y, 8)
  }
}

Objects

Objects group related values together:

let ball = {
  x: 150,
  y: 100,
  vx: 3,
  vy: 2,
  size: 20
}

fn setup() {
  size(300, 200)
}

fn draw() {
  background(rgb(30, 30, 40))

  // Update position
  ball.x = ball.x + ball.vx
  ball.y = ball.y + ball.vy

  // Bounce off walls
  if ball.x < ball.size or ball.x > 300 - ball.size {
    ball.vx = -ball.vx
  }
  if ball.y < ball.size or ball.y > 200 - ball.size {
    ball.vy = -ball.vy
  }

  fill(coral)
  circle(ball.x, ball.y, ball.size)
}

Array Functions

len(array) - Number of items
push(array, item) - Add item to end
pop(array) - Remove and return last item
array[i] - Get item at index i

Looping Over Arrays

Use for item in array to loop through items:

fn setup() {
  size(300, 200)
}

fn draw() {
  background(rgb(30, 30, 40))

  let points = [
    {x: 50, y: 50},
    {x: 150, y: 30},
    {x: 250, y: 80},
    {x: 200, y: 150},
    {x: 100, y: 170}
  ]

  // Draw lines between points
  stroke(coral)
  strokeWeight(2)
  for i in 0..len(points) - 1 {
    let p1 = points[i]
    let p2 = points[i + 1]
    line(p1.x, p1.y, p2.x, p2.y)
  }

  // Draw points
  noStroke()
  fill(white)
  for p in points {
    circle(p.x, p.y, 8)
  }
}

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