# How vtkMultiBlockDataSet is rendered in vtk

**URL:** https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352
**Category:** Development
**Created:** [December 28, 2019, 6:44am UTC](https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352 "2019-12-28T06:44:03Z")
**Posts on this page:** 4
**Page:** 1

<div class="post-metadata">

### Author: ![sharon](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.vtk.org/u/sharon)
#### Post date: [December 28, 2019, 6:44am UTC](https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352/1 "2019-12-28T06:44:03Z")

</div>

Dear Experts,

i put several vtkPolyData into vtkMultiBlockDataSet, i am wondering how vtkMultiBlockDataSet is rendered in VTK if my polyData only contain Lines?

It use VBO technique, one VBO for each vtkMultiBlockDataSet?

Because in my situation, i need render very large number of lines, Points/Spheres with high performance, any suggestion is helpful to me

Thanks in advance!

---

<div class="post-metadata">

### Author: ![cory.quammen](https://discourse.vtk.org/user_avatar/discourse.vtk.org/cory.quammen/32/6751_2.png) [@cory.quammen](https://discourse.vtk.org/u/cory.quammen)
#### Post date: [January 2, 2020, 10:54pm UTC](https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352/2 "2020-01-02T22:54:12Z")

</div>

@ken-martin

---

<div class="post-metadata">

### Author: ![ken-martin](https://discourse.vtk.org/user_avatar/discourse.vtk.org/ken-martin/32/884_2.png) [@ken-martin](https://discourse.vtk.org/u/ken-martin)
#### Post date: [January 6, 2020, 3:24pm UTC](https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352/3 "2020-01-06T15:24:30Z")

</div>

Depends on which mapper you are using. Assuming vtkCompositePolyDataMapper2 It combines polydata into the minimum number of VBOs possible. Multiple polydata can use the same VBO.

---

<div class="post-metadata">

### Author: ![sharon](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.vtk.org/u/sharon)
#### Post date: [January 7, 2020, 3:02am UTC](https://discourse.vtk.org/t/how-vtkmultiblockdataset-is-rendered-in-vtk/2352/4 "2020-01-07T03:02:35Z")

</div>

Thank you Cory for your kind help!