Exhibit #4: Getting Info about Uniforms

Uniforms

What We Did

• You can get the number of uniforms that are used in a program with gl.getProgramParameter(<program>, gl.ACTIVE_UNIFORMS).
• You can then get information about the uniform with the given index with gl.getActiveUniform(<program>, <uniform-index>);.
  • Like the vertex attribute cause, the index goes from 0 to gl.getProgramParameter(<program>, gl.ACTIVE_UNIFORMS)-1.
  • You get an object that tells you the name, size, and the type of the uniform.
    The size is not 1 if it is a uniform array.
  • For a uniform array, you get the name of the first entry.
• You can get the location of a uniform with gl.getUniformLocation(<program>, <uniform-name>)
  • Unlike the vertex attribute case, this does not simply return an integer because uniforms can be arrays.
  • Instead, you get an object which represents the location.
  • This object does not change during the lifetime of the program, so you can get all locations once and use them repeatedly afterwards.
• Hint: Use these functions to build better abstractions around uniforms.