   var matrix = m4.xRotate(viewProjectionMatrix, modelXRotationRadians);
    matrix = m4.yRotate(matrix, modelYRotationRadians);

    // Set the matrix.
    gl.uniformMatrix4fv(matrixLocation, false, matrix);

    // Tell the shader to use texture unit 0 for u_texture
    gl.uniform1i(textureLocation, 0);

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

    requestAnimationFrame(drawScene);
  }
}

//