Highlight/Apply color to a specific part of a big mesh

[ziguri]

I do have only ONE big mesh imported to BabylonJS. I need to visually highlight a small part (let us call it HotSpot) of the big mesh.

What I did so far:

• Extracted all the positions via getVerticesData
• Collected the vertices
• Filtered only vertices of interest (HotSpot)

So I ended up in an array vertexMapHS comprising all the HotSpot vertices. 

Now I need to either highlight using a HighlightLayer or apply a different color all the vertices in vertexMapHS. 

Does anybody have a hint how to do that?

Here is the playground of what I have got so far:

https://www.babylonjs-playground.com/#XG8RH3#7

Thx in advance

[brianzinn]

If you want to apply a color to a vertex for hotspotting facets - here is a good start and it explains the structure of the Colors array:

https://babylonjsguide.github.io/advanced/Custom#color
Note: I think you have to fill the entire array, so can't use filter like in your PG.

HighlightLayer, I think, would require two separate meshes.  One for hotspot and one for not, so doesn't look like an easy option.

[Wingnut]

Hi guys.

   Ziguri, if the objective is to focus user's attention at a certain location upon the model, then this might be a job for Babylon decals.

They have the abilities to contour to a bumpy surface, and they have full Babylon Material powers, such as transparency, colors, textures, post-processing, etc.

Keep in mind that decals are created ESPECIALLY-FOR the surface-contour beneath them.  If you try to re-position a decal post-creation, it will NOT live-update its contours.

So, if you need to drag a decal:

- When pointerMove begins, dispose the old decal, switch to a grabbing-hand cursor for your pointer.

- OnPointerUp (drop)... normalize pointer cursor, get a fresh pickedPoint somehow, and create a NEW decal upon the mesh... there.  It will have fresh surface-conforming contours.

*shrug*  At least that's what I would do, if I ever had to drag a decal. 

[Wingnut]

AND... there's one more "old school" way to put user's attention/eyes... at a certain location.  It has been used in the entertainment industry for a LONG LONG time.

The world famous... spotlight.    No, you can't use 1000 of them all at the same time, but still, for certain tasks... light-it-up, baby. 

What?  Another way?  Okay, okay, you can also "encircle" an area on the surface of a mesh... with a ring of short-lifetime sparkly particles.  This is the "up-town" way of focusing user attention at a certain place.  Circus-grade highlighting.     It's not exactly your grandfather's targeting reticle, is it?  And it's not so easy to place onto the surface of a mesh.