The curvePoint() function in p5.js is used to evaluate the coordinates of a curve at the given point. It takes in the coordinates of the 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 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:
curvePoint( 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 curve value at the given position.
The examples below illustrates the curvePoint() function in p5.js:
Example 1:
function setup() { createCanvas(600, 300); textSize(18); curvePointLocationSlider = createSlider(0, 1, 0, 0.1); curvePointLocationSlider.position(20, 40); } function draw() { background("green"); fill("black"); text( "Move the slider to change the location of the displayed curve point", 10, 20 ); // Get the required location of curve curvePointLocationValue = curvePointLocationSlider.value(); let p1 = { x: 50, y: 250 }; let p2 = { x: 140, y: 150 }; let p3 = { x: 400, y: 150 }; let p4 = { x: 350, y: 250 }; // Draw curve using curveVertex() beginShape(); curveVertex(p1.x, p1.y); curveVertex(p2.x, p2.y); curveVertex(p3.x, p3.y); curveVertex(p4.x, p4.y); endShape(); // Find the X and Y coordinate using the curvePoint() function let pointX = curvePoint(p1.x, p2.x, p3.x, p4.x, curvePointLocationValue); let pointY = curvePoint(p1.y, p2.y, p3.y, p4.y, curvePointLocationValue); fill("orange"); // Display a circle at that point circle(pointX, pointY, 10); } |
Output:
Example 2:
function setup() { createCanvas(600, 300); textSize(18); 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 curve maxPoints = maxPointsSlider.value(); let p1 = { x: 50, y: 250 }; let p2 = { x: 100, y: 150 }; let p3 = { x: 500, y: 150 }; let p4 = { x: 350, y: 250 }; // Draw curve using curveVertex() beginShape(); curveVertex(p1.x, p1.y); curveVertex(p2.x, p2.y); curveVertex(p3.x, p3.y); curveVertex(p4.x, p4.y); endShape(); for (let i = 0; i <= maxPoints; i++) { // Calculate step using the maximum number of points let step = i / maxPoints; // Find the X and Y coordinate using the curvePoint() function let pointX = curvePoint(p1.x, p2.x, p3.x, p4.x, step); let pointY = curvePoint(p1.y, p2.y, p3.y, p4.y, step); fill("orange"); // Display a circle at that point circle(pointX, pointY, 10); } } |
Output:
Online editor: https://editor.p5js.org/
Environment Setup: https://www.geeksforgeeks.org/p5-js-soundfile-object-installation-and-methods/
Reference: https://p5js.org/reference/#/p5/curvePoint
