p5.js bezierPoint() Function
The bezierPoint() function in p5.js is used to evaluate the coordinates of a bezier curve at the given point. It takes in the coordinates of the bezier curve for a particular axis and finds the coordinate of the curve at point “t”, which can be specified as a parameter.
The complete position of a point in the bezier curve can be found out by finding using the function once on the x-coordinates and once on the y-coordinates of the curve and then using them together.
Syntax:
bezierPoint( a, b, c, d, t )
Parameters: This function accepts five parameters as mentioned above and described below:
- a: It is a number that specifies the first point of the curve.
- b: It is a number that specifies the first control point of the curve.
- c: It is a number that specifies the second control point of the curve.
- d: It is a number that specifies the second point of the curve.
- t: It is a number between 0 and 1, which is used as the position between the beginning and ending of the curve coordinates.
Return Value: It returns a number which specifies the value of the Bezier curve at the given position.
The examples below illustrates the bezierPoint() function in p5.js:
Example 1:
function setup() { createCanvas(600, 300); textSize(18); bezierPointLocationSlider = createSlider(0, 1, 0, 0.1); bezierPointLocationSlider.position(20, 40); } function draw() { background( "green" ); fill( "black" ); text( "Move the slider to change the location of the displayed bezier point" , 10, 20); // Get the required location of bezier bezierPointLocationValue = bezierPointLocationSlider.value(); let p1 = { x: 50, y: 250 }; let p2 = { x: 140, y: 150 }; let p3 = { x: 400, y: 150 }; let p4 = { x: 500, y: 250 }; noFill(); // Draw bezier using bezier() bezier(p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y); // Find the X and Y coordinate using the bezierPoint() function let pointX = bezierPoint(p1.x, p2.x, p3.x, p4.x, bezierPointLocationValue); let pointY = bezierPoint(p1.y, p2.y, p3.y, p4.y, bezierPointLocationValue); fill( "red" ); // Display it on the sketch ellipse(pointX, pointY, 10, 10); } |
Output:
Example 2:
function setup() { createCanvas(600, 300); textSize(20); maxPointsSlider = createSlider(2, 20, 10, 1); maxPointsSlider.position(20, 40); } function draw() { background( "green" ); fill( "black" ); text( "Move the slider to change the number of intermediate points" , 10, 20); // Get the required location of bezier maxPoints = maxPointsSlider.value(); let p1 = { x: 50, y: 250 }; let p2 = { x: 140, y: 150 }; let p3 = { x: 400, y: 150 }; let p4 = { x: 500, y: 250 }; noFill(); // Draw bezier using bezier() bezier(p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y); for (let i = 0; i <= maxPoints; i++) { let step = i / maxPoints; // Find the X and Y coordinate using the bezierPoint() function let pointX = bezierPoint(p1.x, p2.x, p3.x, p4.x, step); let pointY = bezierPoint(p1.y, p2.y, p3.y, p4.y, step); fill( "red" ); // Display it on the sketch ellipse(pointX, pointY, 8, 8); } } |
Output:
Online editor: https://editor.p5js.org/
Environment Setup: https://www.w3wiki.net/p5-js-soundfile-object-installation-and-methods/
Reference: https://p5js.org/reference/#/p5/bezierPoint
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