WebGL getUniform

README.md

WebGL getUniform

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index.css

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

index.html

<canvas></canvas>

index.js

const gl = document.querySelector('canvas').getContext('webgl');
const prg = createProgram(
    gl,
    `void main() {
       gl_Position = vec4(1);
     }
    `,
    `
    precision highp float;
    uniform vec4 foo;
    uniform vec4 bar;
    void main() {
      gl_FragColor = foo + bar;
    }`);
const fooLoc = gl.getUniformLocation(prg, 'foo');
const barLoc = gl.getUniformLocation(prg, 'bar');
console.log('foo', gl.getUniform(prg, fooLoc));
console.log('bar', gl.getUniform(prg, barLoc));
console.log('err:', glEnumToString(gl, gl.getError()));

function glEnumToString(gl, value) {
  const keys = [];
  for (const key in gl) {
    if (gl[key] === value) {
      keys.push(key);
    }
  }
  return keys.length ? keys.join(' | ') : `0x${value.toString(16)}`;
}

function createShader(gl, type, src) {
  const shader = gl.createShader(type);
  gl.shaderSource(shader, src);
  gl.compileShader(shader);
  if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
    throw new Error(gl.getShaderInfoLog(shader));
  }
  return shader;
}

function createProgram(gl, vs, fs, tf) {
  const program = gl.createProgram();
  gl.attachShader(program, createShader(gl, gl.VERTEX_SHADER, vs));
  gl.attachShader(program, createShader(gl, gl.FRAGMENT_SHADER, fs));
  if (tf) {
     gl.transformFeedbackVaryings(program, tf, gl.INTERLEAVED_ATTRIBS); // gl.SEPARATE_ATTRIBS);
  }
  gl.linkProgram(program);
  if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
    throw new Error(gl.getProgramInfoLog(program));
  }
  return program;
}

jsGist.json

{"name":"WebGL getUniform","settings":{},"filenames":["index.html","index.css","index.js"]}