# vtkMultiBlockDataSet and vtkMultiBlockVolumeMapper...

**URL:** https://discourse.vtk.org/t/vtkmultiblockdataset-and-vtkmultiblockvolumemapper/14166
**Category:** Support
**Created:** [July 4, 2024, 12:29pm UTC](https://discourse.vtk.org/t/vtkmultiblockdataset-and-vtkmultiblockvolumemapper/14166 "2024-07-04T12:29:15Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![codeling](https://discourse.vtk.org/user_avatar/discourse.vtk.org/codeling/32/3792_2.png) [@codeling](https://discourse.vtk.org/u/codeling)
#### Post date: [July 4, 2024, 12:29pm UTC](https://discourse.vtk.org/t/vtkmultiblockdataset-and-vtkmultiblockvolumemapper/14166/1 "2024-07-04T12:29:15Z")

</div>

I’m trying to use `vtkMultiBlockVolumeMapper` to render a `vtkMultiBlockDataSet`. According to the docs of `vtkMultiBlockVolumeMapper`:

> [vtkMultiBlockVolumeMapper](https://vtk.org/doc/nightly/html/classvtkMultiBlockVolumeMapper.html) renders [vtkMultiBlockDataSet](https://vtk.org/doc/nightly/html/classvtkMultiBlockDataSet.html) instances containing [vtkImageData](https://vtk.org/doc/nightly/html/classvtkImageData.html) blocks

But I can’t figure out how to tell the `vtkMultiBlockVolumeMapper` to use a`vtkMultiBlockDataSet` as input:

- `vtkMultiBlockDataSet` derives from `vtkDataObject`, but not from `vtkDataSet` - so using the `SetInputData` method from the `vtkVolumeMapper` as I would do with a simple `vtkImageData` is not an option.
- In `vtkMultiBlockVolumeMapper` itself, I also see no method taking a `vtkMultiBlockDataSet` as input.
- I also haven’t found example code using `vtkMultiBlockVolumeMapper` (but would be willing to provide a pull request once I have a working example).

Probably I’m missing something very obvious, but I’m stuck - please help!

---

<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: [July 4, 2024, 1:57pm UTC](https://discourse.vtk.org/t/vtkmultiblockdataset-and-vtkmultiblockvolumemapper/14166/2 "2024-07-04T13:57:37Z")

</div>

Use `SetInputDataObject` if you have a `vtkMultiBlockDataSet` or use the pattern

```auto
mapper->SetInputConnection(datasource->GetOutputPort())

```

if you have a source object that produces the `vtkMultiBlockDataSet`.

---

<div class="post-metadata">

### Author: ![codeling](https://discourse.vtk.org/user_avatar/discourse.vtk.org/codeling/32/3792_2.png) [@codeling](https://discourse.vtk.org/u/codeling)
#### Post date: [July 8, 2024, 8:36pm UTC](https://discourse.vtk.org/t/vtkmultiblockdataset-and-vtkmultiblockvolumemapper/14166/3 "2024-07-08T20:36:38Z")

</div>

Thanks for the help!

I have created [merge request to the VTK example repo](https://gitlab.kitware.com/vtk/vtk-examples/-/merge_requests/355) with my small demo. Glad about any suggestions!