p5.js constrain() Function

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The constrain() function in p5.js is used to constrain a number between a given minimum and maximum limit.

Syntax:

constrain( n, low, high )

Parameters: This function accept three parameters as mentioned above and described below:

n: It is a number which denotes the value that has to be constrained.
low: It is a number which denotes the minimum limit to which the number is constrained.
high: It is a number which denotes the maximum limit to which the number is constrained.

Return Value: It returns a number with the constrained value.

The example below illustrates the constrain() function in p5.js:

Example 1:

function setup() { 
  createCanvas(650, 200); 
  textSize(20); 
   
  inputElemA = createInput(10); 
  inputElemA.position(30, 40); 
   
  inputElemB = createInput(100); 
  inputElemB.position(30, 60); 
   
  sliderElem = createSlider(-100, 100, 50, 1); 
  sliderElem.position(30, 120); 
} 
   
function draw() { 
  clear(); 
  text("Enter two values between which the "
    + "number would be constrained", 20, 20); 
  text("Move the slider to observe the effects"
    + " of the constrain() function", 20, 100); 
   
  // Convert the string value to a number value 
  inputValA = Number(inputElemA.value()); 
  inputValB = Number(inputElemB.value()); 
  sliderVal = sliderElem.value(); 
   
  text("The slider value is: " + sliderVal, 20, 160); 
   
  // Display the constrained value 
  text("The constrained value is: "
        + constrain(sliderVal, inputValA, 
        inputValB), 20, 180); 
} 

Output:

Example 2:

function setup() { 
  createCanvas(600, 350); 
  textSize(20); 
   
} 
   
function draw() { 
  clear(); 
  text("Move the pointer to see the effect "
        + "of constrain() in the square", 20, 30); 
  text("White circle represents unconstrained"
        + " mouse", 20, 50); 
  text("Red circle represents mouse constrained"
        + " to box dimensions", 20, 70); 
   
  noFill(); 
  square(100, 100, 200); 
   
  circle(mouseX, mouseY, 40); 
   
  // Constrain the mouse x and y position 
  constrainedMouseX = constrain(mouseX, 100, 300); 
  constrainedMouseY = constrain(mouseY, 100, 300); 
   
  fill('red'); 
  circle(constrainedMouseX, constrainedMouseY, 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/constrain

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