# model on top issue in WASM

**URL:** <https://discourse.vtk.org/t/model-on-top-issue-in-wasm/8016>\
**Category:** Development\
**Created:** [March 10, 2022, 2:28am UTC](https://discourse.vtk.org/t/model-on-top-issue-in-wasm/8016 "2022-03-10T02:28:58Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![reichtiger](https://discourse.vtk.org/user_avatar/discourse.vtk.org/reichtiger/32/3671_2.png) [@reichtiger](https://discourse.vtk.org/u/reichtiger)\
**Post date:** [March 10, 2022, 2:28am UTC](https://discourse.vtk.org/t/model-on-top-issue-in-wasm/8016/1 "2022-03-10T02:28:58Z")

</div>

Hello, everyone.  
I have successfully compile VTK-9.1.0 to webassembly and it runs in docker fine.  
Here is the issue when I need to show model on top of others.  
On win11 local C++, it runs OK :

==============================================  
_vtkNew renderer;_

- vtkNew renderWindow;\*

- renderWindow-\>SetMultiSamples(0);\*

- renderWindow-\>AddRenderer(renderer);\*

- vtkNew renderWindowInteractor;\*

- renderWindowInteractor-\>SetRenderWindow(renderWindow);\*

- vtkNew style;\*

- renderWindowInteractor-\>SetInteractorStyle(style);\*

- style-\>SetDefaultRenderer(renderer);\*

- vtkSPtrNew(sphere, vtkSphereSource);\*

- sphere-\>SetCenter(0, 0, 0);\*

- sphere-\>SetRadius(1);\*

- sphere-\>Update();\*

- vtkSPtrNew(sphereMapper, vtkPolyDataMapper);\*

- sphereMapper-\>SetInputData(sphere-\>GetOutput());\*

- vtkSPtrNew(sphereActor, vtkActor);\*

- sphereActor-\>SetMapper(sphereMapper);\*

- sphereActor-\>GetProperty()-\>SetColor(1, 0, 0);\*

- const double units0 = -66000;\*

- sphereMapper-\>SetResolveCoincidentTopologyToPolygonOffset();\*

- sphereMapper-\>SetRelativeCoincidentTopologyLineOffsetParameters(0, units0);\*

- sphereMapper-\>SetRelativeCoincidentTopologyPolygonOffsetParameters(0, units0);\*

- sphereMapper-\>SetRelativeCoincidentTopologyPointOffsetParameter(units0);\*

- // Create pipeline\*

- vtkNew coneSource;\*

- coneSource-\>SetRadius(2);\*

- coneSource-\>SetHeight(4);\*

- coneSource-\>Update();\*

- vtkNew mapper;\*

- mapper-\>SetInputConnection(coneSource-\>GetOutputPort());\*

- vtkNew actor;\*

- actor-\>SetMapper(mapper);\*

- // Add the actors to the scene\*

- renderer-\>AddActor(sphereActor);\*

- renderer-\>AddActor(actor);\*

- // Start rendering app\*

- renderer-\>SetBackground(0.2, 0.3, 0.4);\*

- renderWindow-\>SetSize(400, 400);\*

- renderWindow-\>Render();\*

- // Start event loop\*

- renderWindowInteractor-\>Start();\*  
==========================================

But when I compile them into wasm and run in chrome , it crushs like:

Cone.wasm:0x4c76c Uncaught (in promise) RuntimeError: null function or function signature mismatch  
at vtkOpenGLPolyDataMapper::UpdateShaders(vtkOpenGLHelper&, vtkRenderer\*, vtkActor\*) (Cone.wasm:0x4c76c)  
at vtkOpenGLPolyDataMapper::RenderPieceDraw(vtkRenderer\*, vtkActor\*) (Cone.wasm:0x4f3f8)  
at vtkOpenGLPolyDataMapper::RenderPiece(vtkRenderer\*, vtkActor\*) (Cone.wasm:0x4f773)  
at vtkPolyDataMapper::Render(vtkRenderer\*, vtkActor\*) (Cone.wasm:0xb9592)  
at vtkOpenGLActor::Render(vtkRenderer\*, vtkMapper\*) (Cone.wasm:0x1b10f)  
at vtkActor::RenderOpaqueGeometry(vtkViewport\*) (Cone.wasm:0x9b0a6)  
at vtkRenderer::UpdateOpaquePolygonalGeometry() (Cone.wasm:0xc4d8f)  
at vtkOpenGLRenderer::DeviceRenderOpaqueGeometry(vtkFrameBufferObjectBase\*) (Cone.wasm:0x65cea)  
at vtkOpenGLRenderer::UpdateGeometry(vtkFrameBufferObjectBase\*) (Cone.wasm:0x657c9)  
at vtkOpenGLRenderer::DeviceRender() (Cone.wasm:0x65131)

Does anyone know this ? if I uncomment those “SetResolveCoincidentTopology” lines it can be run without error , but it is not what I want . I need the spere ALWAYS ON TOP of others.

How can I do ?  
Thanks in advance and any advices is appreciated !

William