# Latest

**URL:** https://discourse.vtk.org/latest.md?page=234

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

**Page:** 235

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## [Filter to select subset of IDs from vtkUnstructuredGrid](https://discourse.vtk.org/t/filter-to-select-subset-of-ids-from-vtkunstructuredgrid/1993)

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**Author:** [@Aramos](https://discourse.vtk.org/u/Aramos)\
**Replies:** 0\
**Last updated:** [October 28, 2019, 12:17pm UTC](https://discourse.vtk.org/t/filter-to-select-subset-of-ids-from-vtkunstructuredgrid/1993 "2019-10-28T12:17:51Z")

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Hi, I’m trying to apply a filter to only display 2/3 of the cells of a vtkUnstructuredGrid. I’m finding very little documentation about the usage of filters and I’m a bit lost about how to do that. This is the code I’v…

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## [Molecule builder/ Molecule representation to interact with user.](https://discourse.vtk.org/t/molecule-builder-molecule-representation-to-interact-with-user/1988)

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**Author:** [@pali08](https://discourse.vtk.org/u/pali08)\
**Replies:** 0\
**Last updated:** [October 27, 2019, 11:10pm UTC](https://discourse.vtk.org/t/molecule-builder-molecule-representation-to-interact-with-user/1988 "2019-10-27T23:10:51Z")

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Hello all, I am working on program in which user can build molecule and measure distances between atom (among other things). Example use case: User have some hydrocarbon drawn in render window. Clicking H atom will r…

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## [Nightly Python Releases on Anaconda](https://discourse.vtk.org/t/nightly-python-releases-on-anaconda/1739)

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**Author:** [@banesullivan](https://discourse.vtk.org/u/banesullivan)\
**Replies:** 5\
**Last updated:** [October 26, 2019, 11:56pm UTC](https://discourse.vtk.org/t/nightly-python-releases-on-anaconda/1739 "2019-10-26T23:56:09Z")

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Would anyone be interested in helping set up an Anaconda recipe to build VTK from the master branch on a nightly/periodic basis to keep the Python wheels up to date with the latest developments in VTK? I’ve also posted …

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## [How to compute the intersection of a segment with a tetrahedron](https://discourse.vtk.org/t/how-to-compute-the-intersection-of-a-segment-with-a-tetrahedron/1984)

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**Author:** [@ztdep](https://discourse.vtk.org/u/ztdep)\
**Replies:** 1\
**Last updated:** [October 26, 2019, 2:01pm UTC](https://discourse.vtk.org/t/how-to-compute-the-intersection-of-a-segment-with-a-tetrahedron/1984 "2019-10-26T14:01:33Z")

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Dear sir: I want to know the intersection points of a segment and a tetrahedron. which API can resolve this. Regards

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## [Dashboard status after !6110](https://discourse.vtk.org/t/dashboard-status-after-6110/1971)

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**Author:** [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)\
**Replies:** 3\
**Last updated:** [October 25, 2019, 5:41pm UTC](https://discourse.vtk.org/t/dashboard-status-after-6110/1971 "2019-10-25T17:41:31Z")

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So after merging !6110 (which had green dashboards), master looked a bit rocky on some dashboards. I went and investigated on taanab and bigmac. On the latter, I reproduced the error and then started to bisect over the b…

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## [How to save a vertex data in 2D numpy array into a text vtk file in Python?](https://discourse.vtk.org/t/how-to-save-a-vertex-data-in-2d-numpy-array-into-a-text-vtk-file-in-python/1973)

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**Author:** [@leonard-oz](https://discourse.vtk.org/u/leonard-oz)\
**Replies:** 1\
**Last updated:** [October 25, 2019, 3:24pm UTC](https://discourse.vtk.org/t/how-to-save-a-vertex-data-in-2d-numpy-array-into-a-text-vtk-file-in-python/1973 "2019-10-25T15:24:32Z")

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Dear VTK experts: I have a mesh vertex data which is in 2D numpy array format, how could I save it into a text vtk file in Python? Sorry I am very new to VTK . Thanks.

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## [How to write cell centred data field to an unstructred grid.](https://discourse.vtk.org/t/how-to-write-cell-centred-data-field-to-an-unstructred-grid/1965)

<div class="topic-metadata">

**Author:** [@ztdep](https://discourse.vtk.org/u/ztdep)\
**Replies:** 1\
**Last updated:** [October 25, 2019, 2:19pm UTC](https://discourse.vtk.org/t/how-to-write-cell-centred-data-field-to-an-unstructred-grid/1965 "2019-10-25T14:19:35Z")

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Dear sir: I need to output my cfd data in a FVM way.How to write cell centred data field to an unstructred grid. Regards

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## [Data normalization and size limitations](https://discourse.vtk.org/t/data-normalization-and-size-limitations/1980)

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**Author:** [@Nicolas\_Rannou](https://discourse.vtk.org/u/Nicolas_Rannou)\
**Replies:** 0\
**Last updated:** [October 25, 2019, 1:38pm UTC](https://discourse.vtk.org/t/data-normalization-and-size-limitations/1980 "2019-10-25T13:38:08Z")

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Hi there, I’ve been over the vtk.js source code and I could not find: if the image data was being normalized somewhere in the visualization pipeline before being sent to the shaders if there was a limitation in terms …

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## [Update file names with ImageWriter](https://discourse.vtk.org/t/update-file-names-with-imagewriter/1955)

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**Author:** [@1111](https://discourse.vtk.org/u/1111)\
**Replies:** 2\
**Last updated:** [October 24, 2019, 4:56am UTC](https://discourse.vtk.org/t/update-file-names-with-imagewriter/1955 "2019-10-24T04:56:51Z")

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Hi, I created a program to save images by key operation. The current problem is to be overwritten because the names saved by keyspress are the same. Every time I press the key, I want to save the file as: slice\_1\_512…

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## [Wrapper hierarchy file](https://discourse.vtk.org/t/wrapper-hierarchy-file/1552)

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**Author:** [@Ron84](https://discourse.vtk.org/u/Ron84)\
**Replies:** 19\
**Last updated:** [October 23, 2019, 10:16pm UTC](https://discourse.vtk.org/t/wrapper-hierarchy-file/1552 "2019-10-23T22:16:15Z")

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Hello @ben.boeckel, I have heard that you are familiar with the wrapper “engine” of VTK and you can help me with a problem of my library. I don’t know how to fix this error: \[ 66%\] Python Wrapping - generating vtkboolP…

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## [Elevation terrain with tiled texture](https://discourse.vtk.org/t/elevation-terrain-with-tiled-texture/1615)

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**Author:** [@tbenega](https://discourse.vtk.org/u/tbenega)\
**Replies:** 6\
**Last updated:** [October 23, 2019, 7:00pm UTC](https://discourse.vtk.org/t/elevation-terrain-with-tiled-texture/1615 "2019-10-23T19:00:46Z")

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Hello guys, Is it possible to render a terrain with a texture like this example: https://kitware.github.io/vtk-js/examples/ElevationReader.html, but with tiled format image (multiple images)? We have the web service t…

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## [Streamlines generation using polydata](https://discourse.vtk.org/t/streamlines-generation-using-polydata/1949)

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**Author:** [@Sathiya\_Moorthy](https://discourse.vtk.org/u/Sathiya_Moorthy)\
**Replies:** 3\
**Last updated:** [October 22, 2019, 5:08pm UTC](https://discourse.vtk.org/t/streamlines-generation-using-polydata/1949 "2019-10-22T17:08:04Z")

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How can i use the vtkStreamtracer to generate a streamline with my polydata Sample code is here: auto poly\_data = GetPolyData(entity); ( This polydata contains Points and Verts) // Here I am setting Veloc…

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## [How to properly clean a polydata with duplicated points](https://discourse.vtk.org/t/how-to-properly-clean-a-polydata-with-duplicated-points/1956)

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**Author:** [@Paolo\_Lampitella](https://discourse.vtk.org/u/Paolo_Lampitella)\
**Replies:** 4\
**Last updated:** [October 22, 2019, 9:20am UTC](https://discourse.vtk.org/t/how-to-properly-clean-a-polydata-with-duplicated-points/1956 "2019-10-22T09:20:37Z")

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Dear all, I’m a super-casual C++/VTK user and this is my first post here, so excuse my possible naivety, especially in coding (my daily job involves Fortran). I have troubles in understanding what is the proper way to …

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## [Recoloring](https://discourse.vtk.org/t/recoloring/1951)

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**Author:** [@gib](https://discourse.vtk.org/u/gib)\
**Replies:** 0\
**Last updated:** [October 20, 2019, 3:14am UTC](https://discourse.vtk.org/t/recoloring/1951 "2019-10-20T03:14:25Z")

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Starting from a set of 3D points, I generate a 2D triangular unstructured grid in a vtkPolyData and use the z values to assign colors to the points, using a vtkLookupTable. The vtkPolyData is then rendered as a surface.…

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## [What's the difference and respective use for GenericRenderWindow vs RenderWindow vs WebGLRenderWindow?](https://discourse.vtk.org/t/whats-the-difference-and-respective-use-for-genericrenderwindow-vs-renderwindow-vs-webglrenderwindow/1241)

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**Author:** [@mjkd](https://discourse.vtk.org/u/mjkd)\
**Replies:** 1\
**Last updated:** [October 18, 2019, 11:06pm UTC](https://discourse.vtk.org/t/whats-the-difference-and-respective-use-for-genericrenderwindow-vs-renderwindow-vs-webglrenderwindow/1241 "2019-10-18T23:06:51Z")

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The vtk.js API docs for GenericRenderWindow only show the code implementation, and the WebGL one says it is “designed to view/render a vkRenderWindow”, (also probably typo here? vtk?) but isn’t that what the regular Rend…

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## [vtkImageReslice "Fills Background" with Zeros. How Can I Change this Behavior?](https://discourse.vtk.org/t/vtkimagereslice-fills-background-with-zeros-how-can-i-change-this-behavior/1882)

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**Author:** [@MichelleKline](https://discourse.vtk.org/u/MichelleKline)\
**Replies:** 10\
**Last updated:** [October 18, 2019, 10:18pm UTC](https://discourse.vtk.org/t/vtkimagereslice-fills-background-with-zeros-how-can-i-change-this-behavior/1882 "2019-10-18T22:18:55Z")

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Hello, I have a DICOM volume that was acquired in a double-oblique orientation on the scanner. After reading the DICOM using vtkDICOMImageReader, I pipe the volume through vtkImageReslice, then use the DICOM image attr…

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## [Render window output is black when I use vtkGPUVolumeRayCastMapper python](https://discourse.vtk.org/t/render-window-output-is-black-when-i-use-vtkgpuvolumeraycastmapper-python/1938)

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**Author:** [@kimia.af1998](https://discourse.vtk.org/u/kimia.af1998)\
**Replies:** 14\
**Last updated:** [October 18, 2019, 7:06pm UTC](https://discourse.vtk.org/t/render-window-output-is-black-when-i-use-vtkgpuvolumeraycastmapper-python/1938 "2019-10-18T19:06:28Z")

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Hi I use vtkGPUVolumeRayCastMapper to render a DICOM volume. The output window is black but when I use vtkFixedPointVolumeRayCastMapper it works and volume will be displayed. I also use QVTKRenderWindowInteractor widge…

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## [Applied transformation matrix of vtkProcrustesAlignmentFilter in similarity mode](https://discourse.vtk.org/t/applied-transformation-matrix-of-vtkprocrustesalignmentfilter-in-similarity-mode/1948)

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**Author:** [@jonas](https://discourse.vtk.org/u/jonas)\
**Replies:** 0\
**Last updated:** [October 18, 2019, 10:02am UTC](https://discourse.vtk.org/t/applied-transformation-matrix-of-vtkprocrustesalignmentfilter-in-similarity-mode/1948 "2019-10-18T10:02:17Z")

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Hi, Is there a way to retrieve the transformation matrix that is applied by the vtkProcrustesAlignmentFilter? We want to apply this filter to align 2 shapes (meshes of 10.000 corresponding points) on each other in simi…

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## [how to run vtkCollisionDetectionFilter with VTK 8.2.0?](https://discourse.vtk.org/t/how-to-run-vtkcollisiondetectionfilter-with-vtk-8-2-0/1946)

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**Author:** [@rai-sam](https://discourse.vtk.org/u/rai-sam)\
**Replies:** 0\
**Last updated:** [October 18, 2019, 7:22am UTC](https://discourse.vtk.org/t/how-to-run-vtkcollisiondetectionfilter-with-vtk-8-2-0/1946 "2019-10-18T07:22:51Z")

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I want to highlight collision areas of actors. How I can implement vtkCollisionDetectionFilter with VTK 8.2.0? If No, when we will be getting the next version release? Because I am also interested to use: actor-\>GetPro…

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## [How to use polydata to cut polydata？](https://discourse.vtk.org/t/how-to-use-polydata-to-cut-polydata/1940)

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**Author:** [@KeyboardMan](https://discourse.vtk.org/u/KeyboardMan)\
**Replies:** 2\
**Last updated:** [October 18, 2019, 5:18am UTC](https://discourse.vtk.org/t/how-to-use-polydata-to-cut-polydata/1940 "2019-10-18T05:18:22Z")

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I tried using vtkBooleanOprationPolydataFilter, but the effect was not good. Is there any other way to use it?

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## [Translucent texture for texture coordinates outside \[0,1\]](https://discourse.vtk.org/t/translucent-texture-for-texture-coordinates-outside-0-1/1791)

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**Author:** [@drpeterfranz](https://discourse.vtk.org/u/drpeterfranz)\
**Replies:** 17\
**Last updated:** [October 18, 2019, 4:20am UTC](https://discourse.vtk.org/t/translucent-texture-for-texture-coordinates-outside-0-1/1791 "2019-10-18T04:20:43Z")

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I have a 3D geological model. I would now like to project a 2D map onto its surface; however the map only covers some parts of the 3D model surface. Currently I have set repetition off; but the effect is that parts of th…

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## [VTK performance comparison using Quadro and Geforce cards](https://discourse.vtk.org/t/vtk-performance-comparison-using-quadro-and-geforce-cards/1942)

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**Author:** [@JoseJaramillo](https://discourse.vtk.org/u/JoseJaramillo)\
**Replies:** 8\
**Last updated:** [October 18, 2019, 3:04am UTC](https://discourse.vtk.org/t/vtk-performance-comparison-using-quadro-and-geforce-cards/1942 "2019-10-18T03:04:24Z")

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Hi all, Has someone recently compared a Quadro vs a Geforce card with similar specs to see if VTK performance improves? If so, any feedback would be appreciated. Thanks!

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## [Possible to use different interaction styles across viewports?](https://discourse.vtk.org/t/possible-to-use-different-interaction-styles-across-viewports/1926)

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**Author:** [@banesullivan](https://discourse.vtk.org/u/banesullivan)\
**Replies:** 3\
**Last updated:** [October 17, 2019, 9:07pm UTC](https://discourse.vtk.org/t/possible-to-use-different-interaction-styles-across-viewports/1926 "2019-10-17T21:07:39Z")

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When having several viewports in one vtkRenderWindowInteractor, is it possible to set a different interactor style for each viewport such that one viewport shows a renderer with trackball style and another shows with ima…

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## [Cannot Control Opacity of vtkImageActors](https://discourse.vtk.org/t/cannot-control-opacity-of-vtkimageactors/1943)

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**Author:** [@MichelleKline](https://discourse.vtk.org/u/MichelleKline)\
**Replies:** 8\
**Last updated:** [October 17, 2019, 8:48pm UTC](https://discourse.vtk.org/t/cannot-control-opacity-of-vtkimageactors/1943 "2019-10-17T20:48:44Z")

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Hello, I am displaying one image overlaying another image in a vtkRenderWindow. I do so by using vtkImageActor. Prior to adding each vtkImageActor to the vtkRenderer, each image has been mapped through vtkImageMapToCo…

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## [vtkPoissonReconstruction (vtkPCANormalEstimation) errors, flipped surface normals](https://discourse.vtk.org/t/vtkpoissonreconstruction-vtkpcanormalestimation-errors-flipped-surface-normals/1939)

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**Author:** [@sbucc](https://discourse.vtk.org/u/sbucc)\
**Replies:** 0\
**Last updated:** [October 16, 2019, 5:43pm UTC](https://discourse.vtk.org/t/vtkpoissonreconstruction-vtkpcanormalestimation-errors-flipped-surface-normals/1939 "2019-10-16T17:43:17Z")

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Hi, I’m using vtkPoissonReconstruction to rebuild a mesh, with code that pretty much copies the example in https://lorensen.github.io/VTKExamples/site/Cxx/Points/PoissonExtractSurface/. It works fine on most input meshes…

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## [vtk compile error on embedded linux](https://discourse.vtk.org/t/vtk-compile-error-on-embedded-linux/1912)

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**Author:** [@emily-5728](https://discourse.vtk.org/u/emily-5728)\
**Replies:** 5\
**Last updated:** [October 16, 2019, 1:23pm UTC](https://discourse.vtk.org/t/vtk-compile-error-on-embedded-linux/1912 "2019-10-16T13:23:35Z")

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hello， I want to use the vtk library on the am5728 (armv7 core, run linux operating system) chip and use cmake-gui for cross-compilation on Ubuntu. The compiler prompts: system is unknown to make, for arm\_linux\_gnueab…

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## [error](https://discourse.vtk.org/t/error/1936)

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**Author:** [@kingming](https://discourse.vtk.org/u/kingming)\
**Replies:** 1\
**Last updated:** [October 16, 2019, 1:19pm UTC](https://discourse.vtk.org/t/error/1936 "2019-10-16T13:19:46Z")

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CMake Error at CMakeLists.txt:4 (FIND\_PACKAGE): By not providing “FindVTK.cmake” in CMAKE\_MODULE\_PATH this project has asked CMake to find a package configuration file provided by “VTK”, but CMake did not find one. C…

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## [IsA() errors](https://discourse.vtk.org/t/isa-errors/1916)

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**Author:** [@toddy](https://discourse.vtk.org/u/toddy)\
**Replies:** 9\
**Last updated:** [October 15, 2019, 6:59pm UTC](https://discourse.vtk.org/t/isa-errors/1916 "2019-10-15T18:59:02Z")

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There a few places in the VTK code where calling IsA() is flawed. Classes vtkOpenGL2ContextDevice2D, vtkSimpleTransform, vtkXXX do not exist, so the code should either be deleted or the class name changed. Classes vtk…

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## [Now useDepthPeeling Supported?](https://discourse.vtk.org/t/now-usedepthpeeling-supported/1930)

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**Author:** [@rjsgml5698](https://discourse.vtk.org/u/rjsgml5698)\
**Replies:** 1\
**Last updated:** [October 15, 2019, 2:38pm UTC](https://discourse.vtk.org/t/now-usedepthpeeling-supported/1930 "2019-10-15T14:38:00Z")

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Hello. I found the following sentence. Now DepthPeeling Supported? ### useDepthPeeling (set/get Boolean) Turn on/off rendering of translucent material with depth peeling technique. The render window must have alpha bit…

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## [Vanishing cursor](https://discourse.vtk.org/t/vanishing-cursor/1929)

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**Author:** [@toddy](https://discourse.vtk.org/u/toddy)\
**Replies:** 4\
**Last updated:** [October 15, 2019, 1:18am UTC](https://discourse.vtk.org/t/vanishing-cursor/1929 "2019-10-15T01:18:52Z")

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The Discourse text editor drives me crazy. Every time I use a toolbar button for text emphasis the cursor disappears. It reappears when I select hide/show preview. Can someone please fix this?

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