# Problem with Gouraud shading and bitmap texture

**URL:** https://discourse.vtk.org/t/problem-with-gouraud-shading-and-bitmap-texture/11869
**Category:** Development
**Tags:** vtkjs
**Created:** [July 3, 2023, 2:55pm UTC](https://discourse.vtk.org/t/problem-with-gouraud-shading-and-bitmap-texture/11869 "2023-07-03T14:55:36Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Jon](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/j/3bc359/32.png) [@Jon](https://discourse.vtk.org/u/Jon)
#### Post date: [July 3, 2023, 2:55pm UTC](https://discourse.vtk.org/t/problem-with-gouraud-shading-and-bitmap-texture/11869/1 "2023-07-03T14:55:36Z")

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Good day everyone,

I’m having difficulty with applying Gouraud shading to a textured mesh in vtk.js.

I created two meshes identically by adding points and cells from external data. Vertex normals were added to polyData in both cases as explained [here](https://discourse.vtk.org/t/gourard-interpolation-in-vtk-js/11025), and interpolation was set to Gouraud via actor.getProperty(). One of the meshes was given a texture by adding tCoords and js image data.

The problem is that the two meshes end up being shaded differently: while the mesh without a texture is shaded smooth as expected, the textured mesh is shaded flat. Same result if interpolation is set to Phong.

I haven’t had such problem with vtk and python.

Any help will be appreciated  
Jon