[Feature] Make all sources drawable with scalars

[BishopWolf]

Motivation

The motivation is described in the basic form here https://discourse.vtk.org/t/vtkplanesources-as-faces-for-vtkcubesource/15532

This should be extended to ALL sources. I mean, all sources should accept scalars to be drawn in their faces.

Detailed Description

All description and screenshots are presented here https://discourse.vtk.org/t/vtkplanesources-as-faces-for-vtkcubesource/15532

[finetjul]

I'm not sure what the problem is.
You can associate point or cell scalars to vtkPlaneSource output.
Maybe there is a bug somewhere though. Do you have code to reproduce the issue ?

[BishopWolf]

The issue is that vtkPlaneSource is the only source that accepts scalars in a face. All other sources only accept one scalar per face.

[finetjul]

VTK supports:

• associating a unique scalar value per point
• associating a unique scalar value per cell (triangle, quad, ... )

vtkConeSource generates a polydata with points and cells (that connect the points). What prevents you from adding a point scalar array ? (or a cell scalar array?)

[BishopWolf]

This is kinda related #3277
I see every source has a Resolution parameter. You can use that to define how many scalars per face to accept.

[BishopWolf]

vtkConeSource generates a polydata with points and cells (that connect the points). What prevents you from adding a point scalar array ? (or a cell scalar array?)

In my specific case, I was trying with a vtkCubeSource, but I couldn't add scalars in the faces (only 1 scalar per face accepted). I had to build the entire cube with vtkPlaneSource instead.

For vtkConeSource, you have 1 scalar on each triangular polydata, which misses the possibility to add scalars along the base-apex line. Again with Resolution you can define how many.

EDIT: I would assume the vtkSphereSource to be fine right now, but I haven't tested it.

[finetjul]

Thanks for the explanation.

For vtkCubeSource, you could have scalar values inside a 2D texture and you apply the texture onto your cube thanks to texture_coordinates.

For vtkConeSource, we could add a heightResolution parameter (PR is welcome) or using a texture as well could help. But first, texture coordinates would need to be defined at each point (PR is welcome).

[BishopWolf]

I can see that DiskSource is built already good

vtk-js/Sources/Filters/Sources/DiskSource/index.js

Line 94 in 6c0c3dd

// Generate cell connectivity (quads)

Something like this would be fine, I like the generated quads here based on resolutions

[BishopWolf]

Another possibility is to streamline sources to build a larger one, like using the disk source for the bases of the Cone and Cylinder sources; or using the PlaneSource as faces of the Cube source, like I have shown in the example.

[finetjul]

Another possibility is to streamline sources to build a larger one, like using the disk source for the bases of the Cone and Cylinder sources; or using the PlaneSource as faces of the Cube source, like I have shown in the example.

Yes, that works as well. We can rely on "helpers" for that. Both PlaneSource and CubeSource would call a function from a PlaneHelper file...

Feel free to suggest a PR (or let me know if you have funding instead).