# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=139

[Latest](https://discourse.vtk.org/latest.md) · [Categories](https://discourse.vtk.org/categories.md) · [Tags](https://discourse.vtk.org/tags.md)

**Page:** 140

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## [How do I build special lattice model with implicit modeling?](https://discourse.vtk.org/t/how-do-i-build-special-lattice-model-with-implicit-modeling/2651)

<div class="topic-metadata">

**Author:** [@Puth\_Charlie](https://discourse.vtk.org/u/Puth_Charlie)\
**Replies:** 2\
**Last updated:** [February 26, 2020, 4:17am UTC](https://discourse.vtk.org/t/how-do-i-build-special-lattice-model-with-implicit-modeling/2651 "2020-02-26T04:17:47Z")

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In VTK, is there any way to generate a lattice model similar to the one shown below by either implicit modeling or Level-set? If I switch to a lattice model like the one below, how do I build with implicit modeling?

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## [How to decimate a 3D box mesh generated by GMSH?](https://discourse.vtk.org/t/how-to-decimate-a-3d-box-mesh-generated-by-gmsh/2699)

<div class="topic-metadata">

**Author:** [@duy\_duc](https://discourse.vtk.org/u/duy_duc)\
**Replies:** 3\
**Last updated:** [February 25, 2020, 8:24pm UTC](https://discourse.vtk.org/t/how-to-decimate-a-3d-box-mesh-generated-by-gmsh/2699 "2020-02-25T20:24:04Z")

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Hi everyone I am new to VTK. I want to decimate a box meshed with tetrahedra and generated by GMSH. I follow the example for Python here. However, my decimated mesh only contain boundaries of the box and 2D triangle m…

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## [Fill area between lines with different colors](https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681)

<div class="topic-metadata">

**Author:** [@kerim](https://discourse.vtk.org/u/kerim)\
**Replies:** 1\
**Last updated:** [February 24, 2020, 7:25pm UTC](https://discourse.vtk.org/t/fill-area-between-lines-with-different-colors/2681 "2020-02-24T19:25:09Z")

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Hi, Is there a way to plot line that has three dimensions (x, y, z) on two dimensional XY axes and fill the area between this line and some baseline (usually baseline is a constant value line) with color coded by z-valu…

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## [strange problems when running the examples in different languages](https://discourse.vtk.org/t/strange-problems-when-running-the-examples-in-different-languages/2571)

<div class="topic-metadata">

**Author:** [@chaos](https://discourse.vtk.org/u/chaos)\
**Replies:** 7\
**Last updated:** [February 24, 2020, 2:12pm UTC](https://discourse.vtk.org/t/strange-problems-when-running-the-examples-in-different-languages/2571 "2020-02-24T14:12:13Z")

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Hi, I’m a VTK beginner, and I have a strange problem when I ran the VTK example, which was that setting the renderer’s background color would sometimes fail and the background would turn black, and dragging the actor ins…

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## [VTK (pyqt): from world coordinate to display coordinate](https://discourse.vtk.org/t/vtk-pyqt-from-world-coordinate-to-display-coordinate/2626)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 14\
**Last updated:** [February 23, 2020, 3:07am UTC](https://discourse.vtk.org/t/vtk-pyqt-from-world-coordinate-to-display-coordinate/2626 "2020-02-23T03:07:22Z")

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I am using VTK for my project. Now, I need to convert the point from world coordinate to display coordinate, and the result is wrong. The following pyqt code is used to reproduce the problem I meet. from PyQt5.QtWidgets…

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## [copy data from Armadillo matrix to vtkFloatArray](https://discourse.vtk.org/t/copy-data-from-armadillo-matrix-to-vtkfloatarray/2677)

<div class="topic-metadata">

**Author:** [@kerim](https://discourse.vtk.org/u/kerim)\
**Replies:** 4\
**Last updated:** [February 22, 2020, 11:23pm UTC](https://discourse.vtk.org/t/copy-data-from-armadillo-matrix-to-vtkfloatarray/2677 "2020-02-22T23:23:02Z")

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Hi, I use armadillo as math library and I would like to use VTK library to plot data. Is there a way to prepare data for plotting like: fvec(100) DATA; // armadillo vector of type float DATA.ones(100); // sets all 1…

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## [vtkDijkstraGraphGeodesicPath scalar weight question](https://discourse.vtk.org/t/vtkdijkstragraphgeodesicpath-scalar-weight-question/2663)

<div class="topic-metadata">

**Author:** [@Sunderlandkyl](https://discourse.vtk.org/u/Sunderlandkyl)\
**Replies:** 1\
**Last updated:** [February 22, 2020, 4:17pm UTC](https://discourse.vtk.org/t/vtkdijkstragraphgeodesicpath-scalar-weight-question/2663 "2020-02-22T16:17:44Z")

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When UseScalarWeights is enabled, the cost is calculated by dividing the distance by the squared scalar weight: https://gitlab.kitware.com/vtk/vtk/blob/master/Filters/Modeling/vtkDijkstraGraphGeodesicPath.cxx#L165-169 …

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## [VTK 8.2 + EGL offscreen rendering, nvidia driver 440.33.01](https://discourse.vtk.org/t/vtk-8-2-egl-offscreen-rendering-nvidia-driver-440-33-01/2607)

<div class="topic-metadata">

**Author:** [@Sophonet](https://discourse.vtk.org/u/Sophonet)\
**Replies:** 4\
**Last updated:** [February 22, 2020, 1:31pm UTC](https://discourse.vtk.org/t/vtk-8-2-egl-offscreen-rendering-nvidia-driver-440-33-01/2607 "2020-02-22T13:31:13Z")

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Hi there, I am interested in EGL-accelerated offscreen rendering and have read https://blog.kitware.com/off-screen-rendering-through-the-native-platform-interface-egl/. I have successfully built VTK 8.2.0 with using GC…

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## [Best way to overlay multiple 2D images?](https://discourse.vtk.org/t/best-way-to-overlay-multiple-2d-images/2671)

<div class="topic-metadata">

**Author:** [@msmerps](https://discourse.vtk.org/u/msmerps)\
**Replies:** 2\
**Last updated:** [February 21, 2020, 5:22pm UTC](https://discourse.vtk.org/t/best-way-to-overlay-multiple-2d-images/2671 "2020-02-21T17:22:27Z")

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Hi, I’m interested in making overlays of two or more 2D images in VTK (e.g., two MRIs taken multiple years apart). There appear to be two ways of doing this in VTK: via vtkImageBlend (https://itk.org/Wiki/VTK/Examples/…

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## [vtkTextWidget position is not updated when the camera or zoom is used](https://discourse.vtk.org/t/vtktextwidget-position-is-not-updated-when-the-camera-or-zoom-is-used/2604)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 2\
**Last updated:** [February 21, 2020, 4:37pm UTC](https://discourse.vtk.org/t/vtktextwidget-position-is-not-updated-when-the-camera-or-zoom-is-used/2604 "2020-02-21T16:37:32Z")

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Dear all, I am trying to put a text around a object all in 2d. But i found that this widget when i move the camera (or zoom in an area) the objects moves correctly but the text widget stays and is not accordingly update…

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## [explain the vtk architecture design](https://discourse.vtk.org/t/explain-the-vtk-architecture-design/1978)

<div class="topic-metadata">

**Author:** [@kayarre](https://discourse.vtk.org/u/kayarre)\
**Replies:** 21\
**Last updated:** [February 21, 2020, 4:08pm UTC](https://discourse.vtk.org/t/explain-the-vtk-architecture-design/1978 "2020-02-21T16:08:41Z")

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Hi, I have been using VTK for over 5 years now and the various projects derived from it vmtk, paraview, 3Dslicer, etc. generally using the python bindings when developing scripts and such. I am now developing in c++ an…

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## [Sensible default for covalent radius](https://discourse.vtk.org/t/sensible-default-for-covalent-radius/2648)

<div class="topic-metadata">

**Author:** [@Jellby](https://discourse.vtk.org/u/Jellby)\
**Replies:** 3\
**Last updated:** [February 21, 2020, 10:58am UTC](https://discourse.vtk.org/t/sensible-default-for-covalent-radius/2648 "2020-02-21T10:58:44Z")

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I’m using vtkMolecule and vtkSimpleBondPerceiver to display reasonable structures for molecules. But there is a problem when a particular atom does not have a covalent radius specified in the default database: the radius…

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## [Select and delete a widget](https://discourse.vtk.org/t/select-and-delete-a-widget/2629)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 2\
**Last updated:** [February 19, 2020, 3:27pm UTC](https://discourse.vtk.org/t/select-and-delete-a-widget/2629 "2020-02-19T15:27:01Z")

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I am struggle to select an widget in order to delete it. I have an 2d image actor, and over this actor I intend to spread widgets. Nothing special. I have tried vtkDistanceWidget. Take a look what I have tried: void CVT…

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## [Pick a widget](https://discourse.vtk.org/t/pick-a-widget/2573)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 17\
**Last updated:** [February 19, 2020, 11:50am UTC](https://discourse.vtk.org/t/pick-a-widget/2573 "2020-02-19T11:50:22Z")

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I am struggle for a while to achieve something simple: to pick a widget (a distance widget) with mouse pointer, in order to modify it or delete it. Here is my trial: vtkPropPicker\* pPicker = vtkPropPicker::New(); pPi…

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## [From vtkDistanceRepresentation2D to vtkDistanceWidget](https://discourse.vtk.org/t/from-vtkdistancerepresentation2d-to-vtkdistancewidget/2646)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 1\
**Last updated:** [February 19, 2020, 10:17am UTC](https://discourse.vtk.org/t/from-vtkdistancerepresentation2d-to-vtkdistancewidget/2646 "2020-02-19T10:17:18Z")

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If I got a pointer to vtkDistanceRepresentation2D (through a picker), how can I get a pointer to my vtkDistanceWidget which contain this vtkDistanceRepresentation2D ?

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## [Anti-aliasing / multi sampling with vtkGenericOpenGLRenderWindow](https://discourse.vtk.org/t/anti-aliasing-multi-sampling-with-vtkgenericopenglrenderwindow/2463)

<div class="topic-metadata">

**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 1\
**Last updated:** [February 18, 2020, 2:22pm UTC](https://discourse.vtk.org/t/anti-aliasing-multi-sampling-with-vtkgenericopenglrenderwindow/2463 "2020-02-18T14:22:36Z")

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Hello, I am using vtkGenericOpenGLRenderWindow and QVTKOpenGLNativeWidget for VTK rendering in Qt. In order to get the right result when using the vtkSelectVisiblePoints filter, I had to set the number of multi samples…

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## [Custom user interface](https://discourse.vtk.org/t/custom-user-interface/2623)

<div class="topic-metadata">

**Author:** [@Tracy\_Nk](https://discourse.vtk.org/u/Tracy_Nk)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:46am UTC](https://discourse.vtk.org/t/custom-user-interface/2623 "2020-02-17T11:46:42Z")

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I apologise as i’m quite new to VTK Is it possible to create my own user interface (with buttons etc) via C++ to display the volume rendered model? through researching, I’ve seen a lot of people mentioning QT, if that’s…

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## [invalid array name](https://discourse.vtk.org/t/invalid-array-name/2605)

<div class="topic-metadata">

**Author:** [@hao\_hu](https://discourse.vtk.org/u/hao_hu)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:19am UTC](https://discourse.vtk.org/t/invalid-array-name/2605 "2020-02-17T11:19:31Z")

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I write calculator = vtk.vtkArrayCalculator() calculator.SetInputConnection(cellToPoint.GetOutputPort()) calculator.SetAttributeType(vtk.vtkDataObject.POINT ) print(calculator.GetNumberOfScalarAr…

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## [Unable to render image](https://discourse.vtk.org/t/unable-to-render-image/2598)

<div class="topic-metadata">

**Author:** [@Tracy\_Nk](https://discourse.vtk.org/u/Tracy_Nk)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:10am UTC](https://discourse.vtk.org/t/unable-to-render-image/2598 "2020-02-17T11:10:14Z")

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Here is an example code i’m using: #include vtkSmartPointer.h #include vtkDataArray.h #include vtkImageData.h #include vtkImageViewer2.h #include vtkDICOMImageReader.h #include vtkPointData.h #include vtkRenderWin…

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## [vtkContourWidget show no lines](https://discourse.vtk.org/t/vtkcontourwidget-show-no-lines/2640)

<div class="topic-metadata">

**Author:** [@snow](https://discourse.vtk.org/u/snow)\
**Replies:** 0\
**Last updated:** [February 17, 2020, 9:23am UTC](https://discourse.vtk.org/t/vtkcontourwidget-show-no-lines/2640 "2020-02-17T09:23:55Z")

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I’m vtk beginner , i have problems when i used vtkContourWidget with vtkOrientedGlyphFocalPlaneContourRepresentation . I want to create a contour on the screen coordinate, not world coordinate. so I write some code ,…

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## [vtkTransform::Concatenate() is very slow](https://discourse.vtk.org/t/vtktransform-concatenate-is-very-slow/2637)

<div class="topic-metadata">

**Author:** [@mmm](https://discourse.vtk.org/u/mmm)\
**Replies:** 0\
**Last updated:** [February 17, 2020, 7:24am UTC](https://discourse.vtk.org/t/vtktransform-concatenate-is-very-slow/2637 "2020-02-17T07:24:18Z")

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vtkTransform::Concatenate() gets very slow after calling it multiple times. The situation is the following: I call vtkTransform::Concatenate( anotherTransform ) to concatenate another vtkTransform (basically applying…

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## [Parallel Rendering with VTK](https://discourse.vtk.org/t/parallel-rendering-with-vtk/2628)

<div class="topic-metadata">

**Author:** [@guten-tag](https://discourse.vtk.org/u/guten-tag)\
**Replies:** 0\
**Last updated:** [February 16, 2020, 9:07am UTC](https://discourse.vtk.org/t/parallel-rendering-with-vtk/2628 "2020-02-16T09:07:27Z")

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Hi, Community, Recently I have just begun to do some research about parallel rendering with VTK. It’s so wonderful that VTK has provided many interfaces for user to call for. However it’s wired that I just could find vt…

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## [Python 3.8 wrapping support?](https://discourse.vtk.org/t/python-3-8-wrapping-support/2621)

<div class="topic-metadata">

**Author:** [@aborsic](https://discourse.vtk.org/u/aborsic)\
**Replies:** 6\
**Last updated:** [February 15, 2020, 10:33pm UTC](https://discourse.vtk.org/t/python-3-8-wrapping-support/2621 "2020-02-15T22:33:22Z")

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Hi, I am trying to compile VTK 8.2.0 on Windows 10 64bit, Python 3.8.1 64bit, Visual Studio 2015 Update 3. A simple CMake configuration that has worked well with VTK 8.1.2 and Python 3.6 is now throwing hundreds of err…

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## [vtkDataSet.SafeDownCast probleam](https://discourse.vtk.org/t/vtkdataset-safedowncast-probleam/2580)

<div class="topic-metadata">

**Author:** [@hao\_hu](https://discourse.vtk.org/u/hao_hu)\
**Replies:** 2\
**Last updated:** [February 14, 2020, 12:29pm UTC](https://discourse.vtk.org/t/vtkdataset-safedowncast-probleam/2580 "2020-02-14T12:29:40Z")

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I wrote a statement ds = vtk.vtkDataSet.SafeDownCast(reader.GetOutput().GetBlock(i)) in python. I want to convert this data to vtkDataSet type but the converted ds is NoneType. I don’t know what went wrong, can anyone te…

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## [vtkInteractionStyle was not found](https://discourse.vtk.org/t/vtkinteractionstyle-was-not-found/2611)

<div class="topic-metadata">

**Author:** [@siaeleni](https://discourse.vtk.org/u/siaeleni)\
**Replies:** 1\
**Last updated:** [February 13, 2020, 8:36pm UTC](https://discourse.vtk.org/t/vtkinteractionstyle-was-not-found/2611 "2020-02-13T20:36:30Z")

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I have configured vtk, qt and itk using VS 2017 on Windows. (VTK 8.2, Qt 5.14.1 ) Now I want to try a very simple example with the Sphere https://lorensen.github.io/VTKExamples/site/Cxx/GeometricObjects/Sphere/ but I ge…

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## [VTK-4.4.2 Building Problem](https://discourse.vtk.org/t/vtk-4-4-2-building-problem/2614)

<div class="topic-metadata">

**Author:** [@Arda\_Goktogan](https://discourse.vtk.org/u/Arda_Goktogan)\
**Replies:** 1\
**Last updated:** [February 13, 2020, 8:33pm UTC](https://discourse.vtk.org/t/vtk-4-4-2-building-problem/2614 "2020-02-13T20:33:05Z")

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Hi, I’m trying to build VTK-4.4.2 From its source code. When I run make it gives the following error: /home/ardofski/vtk-v4.4.1/Utilities/DICOMParser/DICOMFile.cxx:58:47: error: 'strcmp' was not declared in this sc…

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## [Writing polyData as structured .VTK Imagedata](https://discourse.vtk.org/t/writing-polydata-as-structured-vtk-imagedata/2608)

<div class="topic-metadata">

**Author:** [@ShaneKirkbride](https://discourse.vtk.org/u/ShaneKirkbride)\
**Replies:** 3\
**Last updated:** [February 13, 2020, 7:50pm UTC](https://discourse.vtk.org/t/writing-polydata-as-structured-vtk-imagedata/2608 "2020-02-13T19:50:28Z")

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I can write polyData to a .vtk file but it is an unstructured blob. I need a header to preserve my geometry of my object (I want to read it into an ITK registration application). I saw the example on PolyData to ImageDa…

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## [Draw an actor as 2D overlay using normalized viewport coordinates](https://discourse.vtk.org/t/draw-an-actor-as-2d-overlay-using-normalized-viewport-coordinates/2610)

<div class="topic-metadata">

**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 0\
**Last updated:** [February 13, 2020, 3:49pm UTC](https://discourse.vtk.org/t/draw-an-actor-as-2d-overlay-using-normalized-viewport-coordinates/2610 "2020-02-13T15:49:07Z")

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Hello, I created a 3D scene with some spheres close to a surface. Furthermore I want to render spheres which are not related to the surface. I already tried to place the additional spheres next to the surface but that’s…

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## [How to correctly use vtkPixelBufferObject](https://discourse.vtk.org/t/how-to-correctly-use-vtkpixelbufferobject/2609)

<div class="topic-metadata">

**Author:** [@Seun](https://discourse.vtk.org/u/Seun)\
**Replies:** 0\
**Last updated:** [February 13, 2020, 3:22pm UTC](https://discourse.vtk.org/t/how-to-correctly-use-vtkpixelbufferobject/2609 "2020-02-13T15:22:04Z")

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Hi everyone, I have recently been looking into using vtkPixelBufferObject to perform basic PBO, bind capture data update unbind here’s what I’ve done thus far (if I’m correct) a render window to be set as its cont…

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## [Filling a OpenGLVertexBufferObject with a custom DataArray](https://discourse.vtk.org/t/filling-a-openglvertexbufferobject-with-a-custom-dataarray/2548)

<div class="topic-metadata">

**Author:** [@BotellaA](https://discourse.vtk.org/u/BotellaA)\
**Replies:** 2\
**Last updated:** [February 13, 2020, 1:27pm UTC](https://discourse.vtk.org/t/filling-a-openglvertexbufferobject-with-a-custom-dataarray/2548 "2020-02-13T13:27:35Z")

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Hello! I am trying to provide a custom C++ object to a PolyData by overriding its DataArray. For example, I would like to give a custom DataArray (made of a struct of double) to the PolyData Points. I have an issue whe…

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