p5.Color setAlpha() Method

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The setAlpha() method in p5.js is used to set the alpha component of a p5.Color object. The range of the alpha value is dependent on the current color mode. In the default RGB color mode, the value can be between 0 and 255.

Syntax:

setAlpha( alpha )

Parameters: This method accepts a single parameter as mentioned above and described below:

alpha: It is a number that denotes the new alpha value.

The example below illustrates the setAlpha() method in p5.js:

Example 1:

Javascript

function setup() { 
  createCanvas(600, 300); 
  
  alphaSlider = createSlider(0, 255, 128); 
  alphaSlider.position(30, 50); 
} 
  
function draw() { 
  clear(); 
  textSize(18); 
  
  // Get the alpha value from the slider 
  let alphaValue = alphaSlider.value(); 
  
  let newColor = color(128, 255, 128); 
  
  // Set the alpha value of the color 
  newColor.setAlpha(alphaValue); 
    
  background(newColor); 
  fill('black'); 
  text("Move the slider to change the " + 
       "alpha component of the background color", 
       20, 20); 
    
} 

Output:

Example 2:

Javascript

function setup() { 
  createCanvas(600, 300); 
  
  alphaSlider = createSlider(0, 255, 128); 
  alphaSlider.position(30, 50); 
} 
  
function draw() { 
  clear(); 
  textSize(18); 
  
  noFill(); 
  stroke(0); 
  strokeWeight(50); 
  ellipse(width / 2, height / 2, 150); 
  strokeWeight(1); 
  
  // Get the alpha value from the slider 
  let alphaValue = alphaSlider.value(); 
  
  let newColor = color(255, 128, 128); 
  
  // Set the alpha value of the color 
  newColor.setAlpha(alphaValue); 
    
  noStroke(); 
  background(newColor); 
  fill('black'); 
  text( 
    "Move the slider to change the " + 
    "alpha component of the background color", 
    20, 20); 
    
} 

Output:

Online editor: https://editor.p5js.org/

Environment Setup: https://www.zambiatek.com/p5-js-soundfile-object-installation-and-methods/

Reference: https://p5js.org/reference/#/p5.Color/setAlpha

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