WebGL: test trying to render to layer of 2D texture while reading it (fails as expected)

README.md

WebGL: test trying to render to layer of 2D texture while reading it (fails as expected)

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index.css

/*bug-in-github-api-content-can-not-be-empty*/

index.html

/*bug-in-github-api-content-can-not-be-empty*/

index.js

import 'https://greggman.github.io/webgl-lint/webgl-lint.js';
import * as twgl from 'https://twgljs.org/dist/5.x/twgl-full.module.js';

/** @type WebGL2RenderingContext */
const gl = new OffscreenCanvas(1, 1).getContext('webgl2');
const tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D_ARRAY, tex);
gl.texStorage3D(gl.TEXTURE_2D_ARRAY, 1, gl.RGBA8, 1, 1, 2);
gl.texSubImage3D(gl.TEXTURE_2D_ARRAY, 0, 0, 0, 0, 1, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, new Uint8Array([64, 128, 255, 192]));

const vs = `#version 300 es
void main() {
  gl_PointSize = 1.0;
  gl_Position = vec4(0, 0, 0, 1);
}
`;

const fs = `#version 300 es
precision highp float;

uniform highp sampler2DArray tex;

out vec4 fragColor;

void main() {
  fragColor = texture(tex, vec3(0,0,0)).bgra;
}
`;

const prg = twgl.createProgram(gl, [vs, fs]);
gl.useProgram(prg);

const fb = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
gl.framebufferTextureLayer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, tex, 0, 1);

gl.drawArrays(gl.POINTS, 0, 1);

const pixel = new Uint8Array(4);
gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixel);
console.log(pixel);

jsGist.json

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