CODEWITHSUNDEEP
javascriptjqueryanimationgeometry
Mottenmann
Mottenmann

Reputation: 433

Calculating jumping animation in JavaScript

I'm trying to animate a jump using 3 variables: Jump distance, jump height and maybe jump "speed".

Here is a working JSFiddle demo. However, I'd like the animated jump to be a perfect parabola.

var y = 300;
var x = 0;
var jh = 100;
var jw = 200;
var c = 0;

    var inter = setInterval(function () {
        c++;
        // if box reaches jump height it should fall down
        y = (c >= jh) ? y + 1 : y - 1;
        // if box reaches jump distance
        if (x == jw) clearInterval(inter);

        x++;

        $('.box').css({
            'top': y + 'px',
            'left': x + 'px'
        });

    }, 20);

Upvotes: 4

Views: 1226

Answers (1)

Brandon
Brandon

Reputation: 3494

I'm thinking sine? Assuming jh is "Jump height" and jw is "distance" without cleaning up the existing code you could do something like this:

var y = 300;
var x = 0;
var jh = 100;
var jw = 200;
var c = 0;
var speed = 3;

var inter = setInterval(function () {
    c++;
    y = getHeightAtX(x);
    if (x >= jw) clearInterval(inter);

    x+=speed;

    $('.box').css({
        'bottom': y + 'px',
        'left': x + 'px'
    });

}, 20);

function getHeightAtX(x) {
 return jh*Math.sin(x*Math.PI/jw)   
};

Upvotes: 2

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