在视频对象间使用转场gl-transition之regl-transition 使用

regl-transition

视频：

需要安装：gl-transitions、regl-transitio、regl、gl-shader

import GLTransitions from 'gl-transitions';
import createREGLTransition from 'regl-transition';
import * as createREGL from 'regl';
const videoSrc = [
  'https://media.w3.org/2010/05/sintel/trailer.mp4',
  'http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4',
];
const delay = 2;
const duration = 2;
const loadVideo = src =>
  new Promise((resolve, reject) => {
    const video = document.createElement('video');
    video.width = 500;
    video.height = 400;
    video.crossOrigin = 'anonymous';
    video.preload = 'auto';
    video.load();
    video.src = src;
    video.loop = true;
    video.controls = true;
    video.muted = true;
    // video.autoplay = true;
    video.play();
    resolve(video);
  });
const regl = createREGL({
      container: this.glDemo.nativeElement,
      gl: this.webgl,
    });
    const transitions = GLTransitions.map(t => createREGLTransition(regl, t));

    Promise.all(videoSrc.map(loadVideo)).then((videos: HTMLVideoElement[]) => {
      setTimeout(() => { // 这里用setTimeout是因为视频没这么快播放起来，延迟一下，不然报错 regl.js:48 Error: (regl) invalid texture shape
        regl.frame(({ time }) => {

          const slides = videos.map(video => regl.texture(video).subimage(video));
          const index = Math.floor(time / (delay + duration));
          const from = slides[index % slides.length];
          const to = slides[(index + 1) % slides.length];
          const transition = transitions[index % transitions.length];
          const total = delay + duration;
          const progress = Math.max(0, (time - index * total - delay) / duration);

          transition({ progress, from, to });
        });
      }, 1000)
    });

改进

const createVedio = src => {
  const video = document.createElement('video');
  video.width = 500;
  video.height = 400;
  video.crossOrigin = 'anonymous';
  video.preload = 'auto';
  video.load();
  video.src = src;
  video.loop = true;
  video.controls = true;
  video.muted = true;
  // video.autoplay = true;
  video.play();
  return video;
};

const regl = createREGL({
      container: this.glDemo.nativeElement,
      gl: this.webgl,
    });
    const transitions = GLTransitions.map(t => createREGLTransition(regl, t));
    const videos = videoSrc.map(createVedio);
    setTimeout(() => { // 延迟一下，等video加载完
      regl.frame(({ time }) => {
        const slides = videos.map(video => regl.texture(video).subimage(video));
        const index = Math.floor(time / (delay + duration));
        const from = slides[index % slides.length];
        const to = slides[(index + 1) % slides.length];
        const transition = transitions[index % transitions.length];
        const total = delay + duration;
        const progress = Math.max(0, (time - index * total - delay) / duration);

        transition({ progress, from, to });
      });
    }, 1000)

图片的栗子：

https://github.com/gre/gl-transition-libs/blob/master/packages/regl-transition-example/index.js

文档：

https://github.com/regl-project/regl/blob/gh-pages/API.md#texture-subimage

Reuse resources (buffers, elements, textures, etc.)

Similarly, you should reuse buffers and textures wherever possible. If you are continually uploading data to the GPU you should reuse whatever buffers or textures you can. For example, suppose you want to play a video. Then it is better to reuse the buffer as follows:

// Get a reference to the video element
const myVideo = document.querySelector('video')

// Create a video texture
const videoTexture = regl.texture(myVideo)

regl.frame(() => {
  // Update the frames of the video
  videoTexture.subimage(myVideo)
})

gl-transition

import GLTransitions from 'gl-transitions';

import createTransition from 'gl-transition';
import createTexture from 'gl-texture2d';

const imgSrc = [img1, img2, img3];

const loadImage = src =>
  new Promise((resolve, reject) => {
    const img = new Image();
    img.onload = () => resolve(img);
    img.onerror = reject;
    img.onabort = reject;
    img.src = src;
  });

const imageFrom = await loadImage(img1);
    const imageTo = await loadImage(img2);
    const canvas = this.canvas.nativeElement;

    const gl = this.webgl;
    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
    const buffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
    gl.bufferData(
      gl.ARRAY_BUFFER,
      new Float32Array([-1, -1, -1, 4, 4, -1]), // see a-big-triangle
      gl.STATIC_DRAW
    );
    gl.viewport(0, 0, canvas.width, canvas.height);

    const from = createTexture(gl, imageFrom);
    from.minFilter = gl.LINEAR;
    from.magFilter = gl.LINEAR;

    const to = createTexture(gl, imageTo);
    to.minFilter = gl.LINEAR;
    to.magFilter = gl.LINEAR;

    const transition = createTransition(gl, GLTransitions.find(t => t.name === 'Bounce'));

    // animates forever!
    const loop = (t) => {
      // const transition = createTransition(gl, GLTransitions[Math.floor(Math.random() * GLTransitions.length) % GLTransitions.length]);
      requestAnimationFrame(loop);
      transition.draw((t / 1000) % 1, from, to, canvas.width, canvas.height, { persp: 1.5, unzoom: 0.6 });
    };
    requestAnimationFrame(loop);