p5.js scale() Function

The scale() function in p5.js is used to increase or decrease the size of a shape or model by expanding or contracting its vertices. The scale values are specified as decimal percentages, that is, a scale value of “2.0” would increase the dimensions of the shape by 200%. Similarly, a negative of “-2.0” would decrease the dimensions of the shape by 200%

The objects always scale from their relative origin to the coordinate system. The z parameter of this function is only available in the WebGL mode for scaling across the z-axis.

As scale() is a transformation, every transformation that happens after one call multiplies the effect. If scale() is called within the draw() loop, then the transformation is reset when the loop begins again.

Syntax:

scale( s, [y], [z] )

OR

scale( scales )

Parameters: This function accepts four parameters as mentioned above and described below.

• s: It is a p5.Vector, Number or array of Numbers which define the percent to scale the object. If multiple arguments are given, it denotes the percent to scale the object in the x direction.
• y: It is a Number which denotes the percent to scale the object in the y direction. It is an optional parameter.
• z: It is a Number which denotes the percent to scale the object in the z direction. It is an optional parameter.
• scales: It is a p5.Vector or array of Numbers which specify per-axis percents to scale the object.

The program below illustrate the scale() function in p5.js:

Example 1:

function setup() {
  createCanvas(500, 400);
  textSize(16);

  scaleXslider = createSlider(-3, 3, 1, 0.1);
  scaleXslider.position(30, 30);

  scaleYslider = createSlider(-3, 3, 1, 0.1);
  scaleYslider.position(30, 50);
}

function draw() {
  clear();
  text("Move the sliders to change the scale value", 20, 20);
  fill("red");
  rect(150, 150, 100, 100);

  // Get the scale parameters
  let scaleXValue = scaleXslider.value();
  let scaleYValue = scaleYslider.value();

  text("Scale x value: " + scaleXValue, 20, 350);
  text("Scale y value: " + scaleYValue, 20, 370);

  // Set the scale according to properties
  scale(scaleXValue, scaleYValue);

  fill("green");
  rect(150, 150, 100, 100);
}

Output:

Example 2:

function preload() {
  ballObj = loadModel("models/ball.obj", true);
}

function setup() {
  createCanvas(500, 300, WEBGL);

  scaleXslider = createSlider(-3, 3, 0.5, 0.1);
  scaleXslider.position(30, 30);

  scaleYslider = createSlider(-3, 3, 0.5, 0.1);
  scaleYslider.position(30, 50);

  scaleZslider = createSlider(-3, 3, 0.5, 0.1);
  scaleZslider.position(30, 70);

  debugMode();
}

function draw() {
  clear();
  noStroke();
  lights();
  orbitControl();

  // Get the scale parameters
  let scaleXValue = scaleXslider.value();
  let scaleYValue = scaleYslider.value();
  let scaleZValue = scaleZslider.value();

  // Set the scale according to properties
  scale(scaleXValue, scaleYValue, scaleZValue);

  fill("green")
  model(ballObj);
}

Output:

Reference: https://p5js.org/reference/#/p5/scale