# How can I render volume with vtk webAssembly
**URL:** https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737
**Category:** Support
**Tags:** vtkwasm
**Created:** [April 18, 2024, 9:48am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737 "2024-04-18T09:48:16Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@leo](https://discourse.vtk.org/u/leo)
#### Post date: [April 18, 2024, 9:48am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/1 "2024-04-18T09:48:16Z")
I’m trying to render a volume using vtk webAssembly, but it doesn’t work. I would like to know if vtk webAssembly supports volume rendering, and if not, do I have any alternatives?
---
### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [April 18, 2024, 12:19pm UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/2 "2024-04-18T12:19:18Z")
Yup, that doesn’t work right now. We expect to fix the shaders, soon.
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### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [April 18, 2024, 12:20pm UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/3 "2024-04-18T12:20:54Z")
Can you share any errors/example code so as to help a developer contribute a fix?
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### Author:  [@leo](https://discourse.vtk.org/u/leo)
#### Post date: [April 19, 2024, 2:12am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/4 "2024-04-19T02:12:43Z")
Thanks for your reply. Here’s my code, hope that helps!
example code:
```auto
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
VTK_MODULE_INIT(vtkRenderingOpenGL2)
VTK_MODULE_INIT(vtkInteractionStyle)
VTK_MODULE_INIT(vtkRenderingFreeType)
VTK_MODULE_INIT(vtkRenderingVolumeOpenGL2)
int main(int argc, char* argv[])
{
vtkRenderer *renderer = vtkRenderer::New();
vtkRenderWindow *renWin = vtkRenderWindow::New();
vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
renWin->AddRenderer(renderer);
iren->SetRenderWindow(renWin);
vtkVolume *prop = vtkVolume::New();
vtkSmartVolumeMapper *mapper = vtkSmartVolumeMapper::New();
vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
mapper->SetBlendModeToComposite();
prop->SetMapper(mapper);
prop->SetProperty(volumeProperty);
vtkNIFTIImageReader *reader = vtkNIFTIImageReader::New();
reader->SetFileName("/dataTest/test.nii");
reader->Update();
mapper->SetInputData(reader->GetOutput());
mapper->Modified();
renderer->AddVolume(prop);
renderer->ResetCamera();
renderer->GetRenderWindow()->Render();
iren->Initialize();
iren->Start();
return 0;
}
```
The cmake file comes from [https://gitlab.kitware.com/vtk/vtk/-/tree/master/Examples/Emscripten/Cxx/Cone](https://gitlab.kitware.com/vtk/vtk/-/tree/master/Examples/Emscripten/Cxx/Cone) ,and the different part like this.
```auto
project(VR)
# -----------------------------------------------------------------------------
# Handle VTK dependency
# -----------------------------------------------------------------------------
find_package(VTK
COMPONENTS
FiltersSources # VTK pipeline
InteractionStyle # Mouse handling
RenderingOpenGL2 # For Rendering
RenderingUI # For SDL2 Window
InteractionWidgets
RenderingVolume
RenderingVolumeOpenGL2
RenderingFreeType
RenderingCore
InteractionStyle
)
if (NOT VTK_FOUND)
message("Skipping example: ${VTK_NOT_FOUND_MESSAGE}")
return ()
endif ()
# -----------------------------------------------------------------------------
# Compile example code
# -----------------------------------------------------------------------------
add_executable(VR VR.cxx)
target_link_libraries(VR
PRIVATE
VTK::FiltersSources
VTK::InteractionStyle
VTK::RenderingOpenGL2
VTK::RenderingUI
VTK::InteractionWidgets
VTK::RenderingVolume
VTK::RenderingVolumeOpenGL2
VTK::RenderingFreeType
VTK::RenderingCore
)
# -----------------------------------------------------------------------------
# WebAssembly build options
# -----------------------------------------------------------------------------
set(emscripten_link_options)
set(emscripten_compile_options)
list(APPEND emscripten_link_options
"-lembind"
"SHELL:-s WASM=1"
"SHELL:-s MODULARIZE=1"
"--preload-file=em-preloaded-data@/dataTest"
)
```
Now I can compile successfully, but the rendering failed，and gives the following error：
```auto
[.WebGL-00000A3C0A8D8000] GL_INVALID_OPERATION: Invalid combination of format, type and internalFormat.
```
---
### Author:  [@leo](https://discourse.vtk.org/u/leo)
#### Post date: [April 19, 2024, 2:14am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/5 "2024-04-19T02:14:37Z")
Is there any other way I can render volume on a web?
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### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [April 19, 2024, 1:05pm UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/6 "2024-04-19T13:05:14Z")
> Is there any other way I can render volume on a web?
Yes. Please see [Volume | vtk.js](https://kitware.github.io/vtk-js/api/Rendering_Core_Volume.html)
---
### Author:  [@leo](https://discourse.vtk.org/u/leo)
#### Post date: [April 22, 2024, 2:53am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/8 "2024-04-22T02:53:00Z")
Thank you. I’ll try it.
---
### Author:  [@LucasGandel](https://discourse.vtk.org/u/LucasGandel)
#### Post date: [May 26, 2025, 11:59am UTC](https://discourse.vtk.org/t/how-can-i-render-volume-with-vtk-webassembly/13737/9 "2025-05-26T11:59:36Z")
GLES/WebGL is very strict about the combination of formats but VTK’s `TextureInternalFormats` conversion table is not. For now converting the input image data type to float (e.g. using `vtkImageCast`) should work.
I’ll try to extend `TextureInternalFormats` to support wasm when I find time. If anyone wants to help please ping me