Duplicate image when using gsap scrolltrigger

[sergei86]

Hi all. I have such a problem. When creating a frame transition effect with images, duplication occurs if the image has a transparent background.

Tell me, please, how to fix this?

function animateOnScroll(canvasID, videoInfo) {
      const canvas = document.getElementById(canvasID);
      const canvasContext = canvas.getContext('2d');

      canvas.width = window.innerWidth;
      canvas.height = window.innerHeight;


      for (let i = 0; i <= videoInfo.totalFrames; i++) {
         const img = new Image();
         img.src = videoInfo.currentImage(i);
         videoInfo.images.push(img);
      }

      gsap.to(videoInfo, {
         currentFrame: videoInfo.totalFrames,
         snap: 'currentFrame',
         ease: 'none',
         scrollTrigger: {
            trigger: canvas,
            start: 'top',
            end: `bottom+=${videoInfo.totalFrames * videoInfo.totalTime}`,
            scrub: 2,
            pin: true,
            // markers: true,
         },
         onUpdate: render,
      })

      videoInfo.images[0].onload = () => {
         canvasContext.drawImage(videoInfo.images[0], 0, 0);
      }

      function render() {
         canvasContext.drawImage(videoInfo.images[videoInfo.currentFrame], 0, 0);
      }
   }

   gsap.registerPlugin(ScrollTrigger);

   const videoPresentInfo = {
      totalFrames: 73,
      totalTime: 5,
      images: [],
      currentFrame: 0,
      currentImage: (index) => `../images/frames/presents/${index}.webp`,
   };

[akapowl]

Welcome to the GreenSock forum @sergei86

 

That really sounds more like a canvas question than a GSAP question to me; but you'll probably have to make sure that you clear your canvas before drawing a new image on it. That's also suggested in this answer of an older thread. I hope that will help. Good luck.

 

 

[sergei86]

3 hours ago, akapowl said:

Добро пожаловать на форум GreenSock@sergei86

 

Для меня это действительно больше похоже на вопрос на холсте, чем на вопрос GSAP; но вам, вероятно, придется убедиться, что вы очистили свой холст, прежде чем рисовать на нем новое изображение. Это также предлагается в этом ответе более старой темы. Надеюсь, это поможет. Удачи.

 

 

Thanks a lot, it really helped.

Now it remains to set up transitions between canvases with different canvas.

[GSAP Helper]

It's pretty tough to troubleshoot without a minimal demo - the issue could be caused by CSS, markup, a third party library, your browser, an external script that's totally unrelated to GSAP, etc. Would you please provide a very simple CodePen or CodeSandbox that demonstrates the issue? 

 

Please don't include your whole project. Just some colored <div> elements and the GSAP code is best (avoid frameworks if possible). See if you can recreate the issue with as few dependancies as possible. If not, incrementally add code bit by bit until it breaks. Usually people solve their own issues during this process! If not, then at least we have a reduced test case which greatly increases your chances of getting a relevant answer.

 

Here's a starter CodePen that loads all the plugins. Just click "fork" at the bottom right and make your minimal demo: 

See the Pen aYYOdN by GreenSock (@GreenSock) on CodePen

 

If you're using something like React/Next/Vue/Nuxt or some other framework, you may find StackBlitz easier to use. We have a series of collections with different templates for you to get started on these different frameworks: React/Next/Vue/Nuxt.

 

Once we see an isolated demo, we'll do our best to jump in and help with your GSAP-specific questions.