r primitiveType = gl.TRIANGLES;
    var offset = 0;
    var count = 16 * 6;
    gl.drawArrays(primitiveType, offset, count);
  }
}

// Fill the buffer with the values that define a letter 'F'.
function setGeometry(gl) {
  var positions = new Float32Array([
          // left column front
          0,   0,  0,
          0, 150,  0,
          30,   0,  0,
          0, 150,  0,
          30, 150,  0,
          30,   0,  0,

          // top rung front
          30,   0,  0,
          30,  30,  0,
          100,