WebGL: Is it forbidden to bind the same uniform in a vertex shader and fragment shader?

Question

I am porting an OpenGL framework to JavaScript using Emscriten.

The state is stored in a uniform struct:

struct UniformState {
    ...
    mat4 modelviewprojection_matrix; 
    mat4 modelview_matrix;
    mat3 normal_matrix; 
    mat4 texture_matrix;
    ...
};

that I'd like to access in both the vertex and the fragment shaders as:

uniform UniformState GLUP;

when I do that, I get an error at link time:

Uniform `GLUP`is not linkable between attached shaders

Is it forbidden to bind the same uniform in the vertex shader and fragment shader ?

(if it is forbidden, then clearly I can declare two different sets of uniform variables for each shader, but I'd prefer to have only one, since it makes the code cleaner / simpler, this is why I'm asking in case there is something special to do to make it possible).

Answer 1

Seems to work for me.

Note as Reto mentioned if I don't set the precision I get a link error

"use strict";
var gl = document.createElement("canvas").getContext("webgl");
var program = twgl.createProgramFromScripts(gl, ["vs", "fs"], [], [], log);
log("--done--");

function log(msg) {
  var elem = document.createElement("pre");
  elem.appendChild(document.createTextNode(msg));
  document.body.appendChild(elem);
}

  <script id="vs" type="notjs">
struct Test {
  vec4 color;
  vec4 mult;
};

uniform Test test;
  
attribute vec4 position;

void main() {
  gl_Position = position * test.mult;
}
  </script>
  <script id="fs" type="notjs">
precision highp float;

struct Test {
  vec4 color;
  vec4 mult;
};

uniform Test test;

void main() {
  gl_FragColor = test.color;
  }
  </script>
  <script src="https://twgljs.org/dist/twgl.min.js"></script>