WebGL：异步操作？

// note: mode: 'cors' is because we are loading
// from a different domain

async function main() {
  const response = await fetch('https://i.imgur.com/TSiyiJv.jpg', {mode: 'cors'})
  if (!response.ok) {
    return console.error('response not ok?');
  }
  const blob = await response.blob();
  const bitmap = await createImageBitmap(blob, {
    premultiplyAlpha: 'none',
    colorSpaceConversion: 'none',
  });

  const gl = document.querySelector("canvas").getContext("webgl");

  const tex = gl.createTexture();
  gl.bindTexture(gl.TEXTURE_2D, tex);
  {
    const level = 0;
    const internalFormat = gl.RGBA;
    const format = gl.RGBA;
    const type = gl.UNSIGNED_BYTE;
    gl.texImage2D(gl.TEXTURE_2D, level, internalFormat,
                  format, type, bitmap);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
  }

  const vs = `
  uniform mat4 u_worldViewProjection;
  attribute vec4 position;
  attribute vec2 texcoord;
  varying vec2 v_texCoord;

  void main() {
    v_texCoord = texcoord;
    gl_Position = u_worldViewProjection * position;
  }
  `;
  const fs = `
  precision mediump float;
  varying vec2 v_texCoord;
  uniform sampler2D u_tex;
  void main() {
    gl_FragColor = texture2D(u_tex, v_texCoord);
  }
  `;

  const m4 = twgl.m4;
  const programInfo = twgl.createProgramInfo(gl, [vs, fs]);
  const bufferInfo = twgl.primitives.createCubeBufferInfo(gl, 2);
  const uniforms = {
    u_tex: tex,
  };

  function render(time) {
    time *= 0.001;
    twgl.resizeCanvasToDisplaySize(gl.canvas);
    gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    gl.enable(gl.DEPTH_TEST);

    const fov = 30 * Math.PI / 180;
    const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
    const zNear = 0.5;
    const zFar = 10;
    const projection = m4.perspective(fov, aspect, zNear, zFar);
    const eye = [1, 4, -6];
    const target = [0, 0, 0];
    const up = [0, 1, 0];

    const camera = m4.lookAt(eye, target, up);
    const view = m4.inverse(camera);
    const viewProjection = m4.multiply(projection, view);
    const world = m4.rotationY(time);

    uniforms.u_worldViewProjection = m4.multiply(viewProjection, world);

    gl.useProgram(programInfo.program);
    twgl.setBuffersAndAttributes(gl, programInfo, bufferInfo);
    twgl.setUniforms(programInfo, uniforms);
    gl.drawElements(gl.TRIANGLES, bufferInfo.numElements, gl.UNSIGNED_SHORT, 0);

    requestAnimationFrame(render);
  }
  requestAnimationFrame(render);
}
main();

body { margin: 0; }
canvas { width: 100vw; height: 100vh; display: block; }

<script src="https://twgljs.org/dist/4.x/twgl-full.min.js"></script>
<canvas></canvas>