title: Accessing a structure in vertex shader from the code in WebGl
body: <p>How can I reach this light structure in my vertex shader?</p>
  
  <pre><code>struct LightInfo {
      vec4 Position; // Light position in eye coords.
      vec3 La; // Ambient light intensity
      vec3 Ld; // Diffuse light intensity
      vec3 Ls; // Specular light intensity
  };
  uniform LightInfo Light;
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>shaderProgram.Light = gl.getUniformLocation(shaderProgram, "Light");
  </code></pre>
  
  <p>which compiles, but when I try to insert some value like:</p>
  
  <pre><code>gl.uniform4f(
      shaderProgram.Light.Position,
      parseFloat(document.getElementById("lightPositionX").value),
      parseFloat(document.getElementById("lightPositionY").value),
      parseFloat(document.getElementById("lightPositionZ").value),
      0.0
  );
  </code></pre>
  
  <p>It breaks completely. How would one send this position data into a shader structure?</p>