# vtk.wasm

**URL:** https://discourse.vtk.org/c/web/vtk-wasm/12.md

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

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## [About the vtk.wasm category](https://discourse.vtk.org/t/about-the-vtk-wasm-category/11461)

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**Author:** [@cory.quammen](https://discourse.vtk.org/u/cory.quammen)\
**Replies:** 0

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## [vtkShaderProperty::AddFragmentShaderReplacement behaves differently in WebAssembly (VTK 9.5.2) compared to native OpenGL](https://discourse.vtk.org/t/vtkshaderproperty-addfragmentshaderreplacement-behaves-differently-in-webassembly-vtk-9-5-2-compared-to-native-opengl/16513)

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**Author:** [@HST](https://discourse.vtk.org/u/HST)\
**Replies:** 0\
**Last updated:** [August 17, 2026, 6:28pm UTC](https://discourse.vtk.org/t/vtkshaderproperty-addfragmentshaderreplacement-behaves-differently-in-webassembly-vtk-9-5-2-compared-to-native-opengl/16513 "2026-08-17T18:28:25Z")

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Hi, I use vtkShaderProperty::AddFragmentShaderReplacement() to modify the fragment shader. The following shader replacement works correctly in the native OpenGL build, the actor is red. But it has no visible effect in …

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## [VTK.wasm 'ghost pixel' in browser](https://discourse.vtk.org/t/vtk-wasm-ghost-pixel-in-browser/16479)

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**Author:** [@HST](https://discourse.vtk.org/u/HST)\
**Replies:** 6\
**Last updated:** [July 15, 2026, 6:10am UTC](https://discourse.vtk.org/t/vtk-wasm-ghost-pixel-in-browser/16479 "2026-07-15T06:10:08Z")

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Hi, I started with VTK.wasm. My first goal was, display an empty blue screen. But the display contains white pixel from the bottom left to the top right corner. In a second step, I added a cone. The diagonal white pixe…

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## [Difference between vtk-wasm-sdk Docker image and GitLab tar.gz bundles, and when to use RemoteSession](https://discourse.vtk.org/t/difference-between-vtk-wasm-sdk-docker-image-and-gitlab-tar-gz-bundles-and-when-to-use-remotesession/16365)

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**Author:** [@leehyeonseop](https://discourse.vtk.org/u/leehyeonseop)\
**Replies:** 2\
**Last updated:** [April 9, 2026, 12:23am UTC](https://discourse.vtk.org/t/difference-between-vtk-wasm-sdk-docker-image-and-gitlab-tar-gz-bundles-and-when-to-use-remotesession/16365 "2026-04-09T00:23:09Z")

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Hi, I’m building a web-based VTK application using Emscripten. Currently I compile VTK myself with OffscreenCanvas and threading support, write embind wrappers, and do all rendering client-side in the browser. I have a…

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## [VTK Wasm volume rendering error when using gradient opacity](https://discourse.vtk.org/t/vtk-wasm-volume-rendering-error-when-using-gradient-opacity/16364)

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**Author:** [@Linh](https://discourse.vtk.org/u/Linh)\
**Replies:** 0\
**Last updated:** [March 31, 2026, 9:38am UTC](https://discourse.vtk.org/t/vtk-wasm-volume-rendering-error-when-using-gradient-opacity/16364 "2026-03-31T09:38:10Z")

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Hi, I’m using vtk-wasm-sdk docker to compile my own wasm bundle to use in my web app. This is my render volume code: void renderLoadedVolume() { std::cout \<\< "=== renderLoadedVolume called ===" \<\< std::endl; …

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## [Query with respect to WebGPU Rendering Backend in VTK WASM](https://discourse.vtk.org/t/query-with-respect-to-webgpu-rendering-backend-in-vtk-wasm/16355)

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**Author:** [@RaMmer](https://discourse.vtk.org/u/RaMmer)\
**Replies:** 2\
**Last updated:** [March 26, 2026, 10:31am UTC](https://discourse.vtk.org/t/query-with-respect-to-webgpu-rendering-backend-in-vtk-wasm/16355 "2026-03-26T10:31:43Z")

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Hello, I have been working with VTK WASM over the past few weeks and have been experimenting with the webgpu rendering backend. It works great for my use case which basically most of the time is around is just for visu…

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## [vtkChartXY is rendered only in VtkRemoteView](https://discourse.vtk.org/t/vtkchartxy-is-rendered-only-in-vtkremoteview/16317)

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**Author:** [@Muhammed\_Ali](https://discourse.vtk.org/u/Muhammed_Ali)\
**Replies:** 2\
**Last updated:** [March 7, 2026, 12:50am UTC](https://discourse.vtk.org/t/vtkchartxy-is-rendered-only-in-vtkremoteview/16317 "2026-03-07T00:50:41Z")

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I’m trying to make a 2d plot to run in the browser, but it gets rendered only in VtkRemoteView mode in VtkLocalView it shows just white blank screen and prints Gtk-Message: 03:45:36.722: Not loading module “atk-bridg…

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## [Doubt with VTK wasm](https://discourse.vtk.org/t/doubt-with-vtk-wasm/16203)

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**Author:** [@sridhar-mani](https://discourse.vtk.org/u/sridhar-mani)\
**Replies:** 8\
**Last updated:** [January 9, 2026, 5:32am UTC](https://discourse.vtk.org/t/doubt-with-vtk-wasm/16203 "2026-01-09T05:32:25Z")

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I have been trying to use the vtk wasm sdk 64 bit with workers for the rendering of openfoam files but am getting issue unable to transfer the canvas to the wasm.

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## [Disable rotaion in vtkResliceImageViewer's cursorwidget.](https://discourse.vtk.org/t/disable-rotaion-in-vtkresliceimageviewers-cursorwidget/16212)

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**Author:** [@KSJ](https://discourse.vtk.org/u/KSJ)\
**Replies:** 0\
**Last updated:** [January 6, 2026, 11:29am UTC](https://discourse.vtk.org/t/disable-rotaion-in-vtkresliceimageviewers-cursorwidget/16212 "2026-01-06T11:29:01Z")

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I am using vtkResliceImageViewer to display DICOM images. It has a built-in 2D crosshair that intersects the image. By default, interacting with the crosshair allows both translation and rotation, and rotating the crossh…

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## [vtk wasm script error not a VtkRenderWindow](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076)

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**Author:** [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)\
**Replies:** 3\
**Last updated:** [October 8, 2025, 12:27pm UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076 "2025-10-08T12:27:30Z")

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Wether using samples or my own apps, I get this console error. Is this something I need to be worried about? 2025-10-01 10:35:33.062 ( 0.039s) \[ 7F5534\] vtkSession.cxx:290 ERR| Object null at id=1…

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## [pvd , vtu , vti files with vtk wasm](https://discourse.vtk.org/t/pvd-vtu-vti-files-with-vtk-wasm/16060)

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**Author:** [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)\
**Replies:** 10\
**Last updated:** [October 8, 2025, 10:08am UTC](https://discourse.vtk.org/t/pvd-vtu-vti-files-with-vtk-wasm/16060 "2025-10-08T10:08:44Z")

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Hi, I am a paraview and pyvista user. I’ve stayed away from trame and vtk.js due to server side rendering and slow js rendering. Now that you have vtk wasm I want a simple page to just load a pvd file from disk and plo…

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## [GL\_DEPTH\_COMPONENT32 in opengl es](https://discourse.vtk.org/t/gl-depth-component32-in-opengl-es/16082)

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**Author:** [@Francois\_Merle](https://discourse.vtk.org/u/Francois_Merle)\
**Replies:** 2\
**Last updated:** [October 7, 2025, 2:58pm UTC](https://discourse.vtk.org/t/gl-depth-component32-in-opengl-es/16082 "2025-10-07T14:58:48Z")

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Hi, I’m making an application where I show a vtkImageData in 3D in a QQuickVTKWindow using a vtkSmartVolumeMapper. As vtk is rendering it, there is a warning displayed : GL\_INVALID\_OPERATION: glBlitFramebuffer: Depth/s…

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## [Issue with Using pthread in WASM](https://discourse.vtk.org/t/issue-with-using-pthread-in-wasm/15767)

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**Author:** [@blocky](https://discourse.vtk.org/u/blocky)\
**Replies:** 9\
**Last updated:** [July 2, 2025, 11:26am UTC](https://discourse.vtk.org/t/issue-with-using-pthread-in-wasm/15767 "2025-07-02T11:26:08Z")

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Hello, I’m trying to compile VTK-9.5.0 and use the resulting build as a library for compiling my own C++ code targeting WebAssembly. During the VTK build process, I followed the instructions from the official guide (Bu…

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## [Successful rendering of QT & VTK WebAssembly](https://discourse.vtk.org/t/successful-rendering-of-qt-vtk-webassembly/11439)

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**Author:** [@Miranda](https://discourse.vtk.org/u/Miranda)\
**Replies:** 19\
**Last updated:** [July 1, 2025, 12:14pm UTC](https://discourse.vtk.org/t/successful-rendering-of-qt-vtk-webassembly/11439 "2025-07-01T12:14:52Z")

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I’ve successfully rendered QT/VTK WebAssembly. Qt version: 6.5 VTK version: 9.2.5 If you are interested, please DM me!!!

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## [Transitioning from VTK WASM to VTK WebGPU & WebGPU API Deprecation Issue in VTK 9.4.0](https://discourse.vtk.org/t/transitioning-from-vtk-wasm-to-vtk-webgpu-webgpu-api-deprecation-issue-in-vtk-9-4-0/15268)

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**Author:** [@yarenakin](https://discourse.vtk.org/u/yarenakin)\
**Replies:** 2\
**Last updated:** [February 13, 2025, 2:07pm UTC](https://discourse.vtk.org/t/transitioning-from-vtk-wasm-to-vtk-webgpu-webgpu-api-deprecation-issue-in-vtk-9-4-0/15268 "2025-02-13T14:07:51Z")

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Hello everyone, I am currently using VTK with WASM in my project, and I am considering transitioning to VTK WebGPU in the future. My main concern is whether this transition would be straightforward or if there are major…

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## [vtkWebGPURenderWindow cannot render frame](https://discourse.vtk.org/t/vtkwebgpurenderwindow-cannot-render-frame/14927)

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**Author:** [@blocky](https://discourse.vtk.org/u/blocky)\
**Replies:** 3\
**Last updated:** [December 2, 2024, 3:13pm UTC](https://discourse.vtk.org/t/vtkwebgpurenderwindow-cannot-render-frame/14927 "2024-12-02T15:13:39Z")

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I’m trying to make a web application like vtk-wasm-demos The program runs well with WebGL, but when switching to WebGPU, the canvas appears blank, without any error messages. If I trigger any interactions, I will receive…

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## [vtk wasm project without -sMODULARIZE=1 goes well, but with -sMODULARIZE=1 show nothing](https://discourse.vtk.org/t/vtk-wasm-project-without-smodularize-1-goes-well-but-with-smodularize-1-show-nothing/14726)

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**Author:** [@ruihuasun](https://discourse.vtk.org/u/ruihuasun)\
**Replies:** 1\
**Last updated:** [October 16, 2024, 7:49pm UTC](https://discourse.vtk.org/t/vtk-wasm-project-without-smodularize-1-goes-well-but-with-smodularize-1-show-nothing/14726 "2024-10-16T19:49:46Z")

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I’m looking into wasm recently. And build the vtk-wasm successfully. If I build examples in Examples/Emscripten/Cxx/Cone · master · VTK / VTK · GitLab (kitware.com), the cone is shown in my browser, everything goes well…

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## [Support for Geovis in WASM?](https://discourse.vtk.org/t/support-for-geovis-in-wasm/14673)

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**Author:** [@robynsb](https://discourse.vtk.org/u/robynsb)\
**Replies:** 0\
**Last updated:** [October 7, 2024, 2:22pm UTC](https://discourse.vtk.org/t/support-for-geovis-in-wasm/14673 "2024-10-07T14:22:01Z")

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Hi! I’m thinking of trying to compile my VTK application for WASM. I read that many features are not yet implemented. Where could I read about which features are considered supported and which aren’t? Are the Geovis f…

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## [vtk wasm threads](https://discourse.vtk.org/t/vtk-wasm-threads/12778)

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**Author:** [@0ZzYy0](https://discourse.vtk.org/u/0ZzYy0)\
**Replies:** 4\
**Last updated:** [August 23, 2024, 7:50pm UTC](https://discourse.vtk.org/t/vtk-wasm-threads/12778 "2024-08-23T19:50:26Z")

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When compiling the code with PTHREADS or WASM\_WORKERS enabled, I encountered an error stating “because it was not compiled with ‘atomics’ or ‘bulk-memory’ features.” How can I resolve this issue?

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## [Error of Qt&vtk for Wasm](https://discourse.vtk.org/t/error-of-qt-vtk-for-wasm/13336)

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**Author:** [@leo](https://discourse.vtk.org/u/leo)\
**Replies:** 2\
**Last updated:** [July 23, 2024, 6:17am UTC](https://discourse.vtk.org/t/error-of-qt-vtk-for-wasm/13336 "2024-07-23T06:17:24Z")

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I build successfully with Qt&vtk for wasm, but I can’t display it and get the following error. Can anyone help me with suggestions? Thank you in advance!

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## [CanvasId for WebAssembly](https://discourse.vtk.org/t/canvasid-for-webassembly/14127)

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**Author:** [@Jens\_Munk\_Hansen](https://discourse.vtk.org/u/Jens_Munk_Hansen)\
**Replies:** 8\
**Last updated:** [July 21, 2024, 12:55am UTC](https://discourse.vtk.org/t/canvasid-for-webassembly/14127 "2024-07-21T00:55:40Z")

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I am struggling a bit with multiple render windows for a WASM application. It appears to me that the CanvasId is hard-coded to canvas and VTK only supports a single render window for WASM? Is this the case? We are consi…

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## [Custom allocator for wasm](https://discourse.vtk.org/t/custom-allocator-for-wasm/14186)

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**Author:** [@Jens\_Munk\_Hansen](https://discourse.vtk.org/u/Jens_Munk_Hansen)\
**Replies:** 2\
**Last updated:** [July 9, 2024, 3:43am UTC](https://discourse.vtk.org/t/custom-allocator-for-wasm/14186 "2024-07-09T03:43:54Z")

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Just throwing out a question knowing that WASM does not support virtual memory. Is there a benefit of compling VTK wasm using memkind? Or perhaps another allocator? Anyone with experience in this area? Thanks in advan…

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## [building VTK for webAssembly,ninja: build stopped: subcommand failed](https://discourse.vtk.org/t/building-vtk-for-webassembly-ninja-build-stopped-subcommand-failed/13876)

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**Author:** [@zfzlzh](https://discourse.vtk.org/u/zfzlzh)\
**Replies:** 6\
**Last updated:** [May 16, 2024, 12:15pm UTC](https://discourse.vtk.org/t/building-vtk-for-webassembly-ninja-build-stopped-subcommand-failed/13876 "2024-05-16T12:15:17Z")

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i follow the guide ’ Building using emscripten for WebAssembly’ to build VTK-wasm, but when i use ninja compile ,error occurs: ninja: build stopped: subcommand failed and this is the full info: \[1/1027\] Generating p…

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## [Could NOT find OpenGL (missing: OPENGL\_opengl\_LIBRARY OpenGL)](https://discourse.vtk.org/t/could-not-find-opengl-missing-opengl-opengl-library-opengl/13152)

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**Author:** [@leo](https://discourse.vtk.org/u/leo)\
**Replies:** 2\
**Last updated:** [January 31, 2024, 2:55am UTC](https://discourse.vtk.org/t/could-not-find-opengl-missing-opengl-opengl-library-opengl/13152 "2024-01-31T02:55:37Z")

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When compiling the vtk for WebAssembly , I encountered an error stating “Could NOT find OpenGL (missing: OPENGL\_opengl\_LIBRARY OpenGL) ”.I can’t solve it. Can someone help me? The cmake command is : emcmake cmake \\ -S…

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## [Canvas stretch when resizing browser window](https://discourse.vtk.org/t/canvas-stretch-when-resizing-browser-window/13029)

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**Author:** [@hu243285237](https://discourse.vtk.org/u/hu243285237)\
**Replies:** 6\
**Last updated:** [January 10, 2024, 3:09pm UTC](https://discourse.vtk.org/t/canvas-stretch-when-resizing-browser-window/13029 "2024-01-10T15:09:28Z")

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I am using VTK with WebAssembly, and the canvas css has fixed dimensions of 500 pixels, not fullscreen. The issue I encounter is that when I resize the browser, the canvas content gets stretched. I suspect it might be …

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## [Is there any way to change the InternalFormat?](https://discourse.vtk.org/t/is-there-any-way-to-change-the-internalformat/12298)

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**Author:** [@Zelzahn](https://discourse.vtk.org/u/Zelzahn)\
**Replies:** 0\
**Last updated:** [September 16, 2023, 8:07am UTC](https://discourse.vtk.org/t/is-there-any-way-to-change-the-internalformat/12298 "2023-09-16T08:07:15Z")

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Greetings, I can’t get vtkOpenGLGPUVolumeRayCastMapper nor vtkFixedPointVolumeRayCastMapper to work. I consistently get vtkTextureObject (0x250840): Failed to determine texture parameters., because the InternalFormat is …

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## [\[VTK Wasm\] Axes do not show up when using axes actor](https://discourse.vtk.org/t/vtk-wasm-axes-do-not-show-up-when-using-axes-actor/11917)

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**Author:** [@adityaDas](https://discourse.vtk.org/u/adityaDas)\
**Replies:** 3\
**Last updated:** [July 27, 2023, 7:42am UTC](https://discourse.vtk.org/t/vtk-wasm-axes-do-not-show-up-when-using-axes-actor/11917 "2023-07-27T07:42:21Z")

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We have been trying to use VTK Axes actors to display an axes triad on the scene. In this term, we have followed the instructions stated in this particular example: examples.vtk.org/site/Cxx/Interaction/CallBack/. How…

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## [Unable find "vtkIOExodusModule.h" and IOExodus](https://discourse.vtk.org/t/unable-find-vtkioexodusmodule-h-and-ioexodus/11479)

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**Author:** [@hu243285237](https://discourse.vtk.org/u/hu243285237)\
**Replies:** 9\
**Last updated:** [May 24, 2023, 3:58pm UTC](https://discourse.vtk.org/t/unable-find-vtkioexodusmodule-h-and-ioexodus/11479 "2023-05-24T15:58:30Z")

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I’m front-end engineer, want to build vtk to webAssembly for read exodus file, and follow the “examples/emscripten/cxx” step, it’s work, but when i add exodus reader code, there show message “unable find vtkIOExodusModul…