How to make true parabolas in Adobe Illustrator

Today, a post of technology and activities.

A Google search for making a parabola brought me to a nice quick article on making a parabola-looking curved line on, but for a quick half-day project I am needing to draw a perfect and scalable vector.

Attached is a simple script to run in Adobe Illustrator that was hand-typed to build what is needed for my project.  Some convenient Javascript prompts are included to make it easy to use.

In illustrator, press Ctrl+F12 on Windows or Cmd+F12 on Mac or click File > Scripts > Other script and load the file, then read and follow the prompts.

Click here to download a helpful script for Adobe Illustrator to build a parabola

Here are two parabolas made with this script:

Parabola of x = -0.3 through x = 0.3

Parabola of x = -3 through x = 3

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5 Responses to How to make true parabolas in Adobe Illustrator

  1. Pingback: How to Make Parabolas in Illustrator | Technology - Popular Question & Answer

  2. Deborah says:

    Thanks…just what I was looking for. This is very handy!

  3. Waynos! says:

    Legend! Thank you so much. <3

    ps.. 'Surprised there are not more comments after 3 years. How many downloads in this period all-told?

  4. Muhammad Umar Hassan says:

    I’ve made it a little more useful for those who want more control over what are the parameters of the parabola:

    alert(“The parabola will be generated according to this equation. \ny = a * (x – xOffset)^2 + b * (x – xOffset) + yOffset”);
    xpos = parseFloat(prompt(“X offset”, “0”));
    ypos = parseFloat(prompt(“Y offset”, “0”));
    a = parseFloat(prompt(“Coefficient a”, “1”));
    b = parseFloat(prompt(“Coefficient b”, “0”));
    xstart = parseFloat(prompt(“First Value of X”, “-0.5”));
    xend = parseFloat(prompt(“Last Value of X”, “0.5”));
    steps = parseFloat(prompt(“How many steps should be there?”, 100) );
    scale = parseFloat(prompt(“What should be the scale”, 400));
    strokewidth = 1;
    drawParabola(xpos, ypos, a, b, xstart, xend, steps, strokewidth, scale);

    function drawParabola(xpos, ypos, a, b, xstart, xend, steps, strokewidth, scale)
    var increment = (xend -xstart) / steps;
    var myDoc = app.activeDocument;//.documents.add();
    var myParabolaPath = myDoc.pathItems.add();
    myParabolaPath.stroked = true;
    myParabolaPath.strokeWidth = strokewidth;
    myParabolaPath.filled = false;
    if (xstart > xend)
    var tx = xstart;
    xstart = xend;
    xend = tx;
    var newPoint;
    for (i = xstart; i <= xend; i+= increment)
    newPoint = myParabolaPath.pathPoints.add();
    var x_ = i + xpos;
    newPoint.anchor = [x_ * scale, (a * i* i + b * i + ypos) * scale];
    newPoint.leftDirection = newPoint.anchor;
    newPoint.rightDirection = newPoint.anchor;
    newPoint.pointType = PointType.CORNER;

  5. Tyler says:

    I got the script installed in Illustrator (CC), but when I run it and plug in values, nothing happens. I’m also not sure exactly what the values are that I should put in…but I just used the defaults, and nothing is produced. Any suggestions?

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