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greensock canvas animate

peymanAzizi test
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Warning: Please note

This thread was started before GSAP 3 was released. Some information, especially the syntax, may be out of date for GSAP 3. Please see the GSAP 3 migration guide and release notes for more information about how to update the code to GSAP 3's syntax. 

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Hi and welcome to the GreenSock forums,


GSAP is very flexible in that it can animate any numeric property, it isn't just for DOM/CSS animations.

To animate a line in canvas the basic idea is that you could animate the x and y values of a point object and then repeatedly redraw the line using those updated x/y values in lineTo() like


var ctx,
    point  = {x:0, y:0};
ctx = document.getElementById("canvas").getContext("2d");

//animate x and y of point
TweenMax.to(point, 2, {x:800, y:600, repeat:8, yoyo:true, onUpdate:animateLine});

//draw line onUpdate of tween to new x and y values of point
function animateLine() {
 ctx.moveTo(0, 0);
 ctx.lineTo(point.x, point.y);

demo: http://codepen.io/GreenSock/pen/VjENxv?editors=0010


GSAP doesn't having any drawing methods or functionality specific to canvas. You may have to code a lot of your own logic and drawing routines. A library like SnapSVG might help in some regard but I don't have a lot of experience with it.

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  • 2 years later...

Hi @federicovezzoli 


This thread may be of interest to you.

Blake has this demo drawing a path on a canvas


See the Pen GjYpPr by osublake (@osublake) on CodePen


Another option is to use a SVG and a Pixi canvas sandwiched together so you can use DrawSVG. That's what I did in this demo. The Pixi canvas was used for the spark particles and confetti, but I just kept the bottom layer as a SVG so I could draw the number paths with GSAP and drawSVG. Maybe it'll give you some ideas.


See the Pen RyaJmj by PointC (@PointC) on CodePen

Happy tweening.



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thank you @PointC, I've made some progress, but can't replicate it in pixi the first demo, since pixi does not have dash offset.

I thought to combine svg and webgl, but for different reasons I cannot use that technique.


So, I have an array of cubic bezier coords without animation I just do something like this, and it works:


this.tracks[trackID] = new PIXI.Graphics()
this.tracks[trackID].lineStyle(1, 0xFFFFFF)
for (var i = 1; i < newCubicBezier.length; i++) {
	this.tracks[trackID].lineTo(newCubicBezier[i].x, newCubicBezier[i].y, 1)


But if I place it in a tween, the line is not visible:

//remove the first el
let that = this.tracks[trackID]
TweenMax.staggerTo(newCubicBezier, 2, {
    ease: Sine.easeOut,
    onUpdate: function(){
        console.log("update", this.target, that)
        that.lineTo(this.target.x, this.target.y, 1)
}, 0.05);


I think I'm missing some basic understanding, but couldn't find it.


Wanted to do a codepen demo, but Codepen is not working right now. :(


Thanks a lot!

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I'll preface this with a disclaimer: I don't often draw graphics with Pixi. I mostly use it for sprites, particles, explosions and that kind of crazy stuff so I'm not an expert with the drawing commands.


That being said, I think you'll have to set your lineStyle on each update:


See the Pen axOPrV by PointC (@PointC) on CodePen


I think some of the point data may be off though because this doesn't look quite right. I didn't dive too far into the rest of your code to see what that might be. Maybe a scaling issue? I'm sure you can track it down.


Here's a slightly different approach. I used a dummy target and the Bezier plugin to draw the path on the PIXI stage. Maybe it'll give you some ideas.


See the Pen oOXMOB by PointC (@PointC) on CodePen


Or you can tween an object as well instead of the dummy target.


See the Pen NmqowR by PointC (@PointC) on CodePen


Hopefully that helps a bit. Happy tweening.



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