docs: function AsciiFilter()
  {
      core.AbstractFilter.call(this,
          // vertex shader
          null,
          // fragment shader
          fs.readFileSync(__dirname + '/ascii.frag', 'utf8'),
          // custom uniforms
          {
              dimensions: { type: '4fv', value: new Float32Array([0, 0, 0, 0]) },
              pixelSize:  { type: '1f', value: 8 }
          }
      );
  }