 gl.uniformMatrix4fv(matrixLocation, false, matrix);

        // Draw the geometry.
        var primitiveType = gl.TRIANGLES;
        var offset = 0;
        var count = 16 * 6;
        gl.drawArrays(primitiveType, offset, count);
      }
    }

    requestAnimationFrame(drawScene);
  }
}

// Fill the current ARRAY_BUFFER buffer
// with the values that define a letter 'F'.
function setGeometry(gl) {
  gl.bufferData(
      gl.ARRAY_BUFFER,
      new Float32Array([
          // left column front
          0, 