# How to get the uv coordinate of a mesh

I don’t know if this description is accurate,actually I want to implement a function like:RaycastHit.textureCoord in Unity or Raycaster.intersectObject in Three.js which returns the uv coordinate of the hitten mesh.
After some googling, I found a nice solution on github which implement a part of this function:
https://github.com/playcanvas/engine/pull/989

But that is not enough
Does anyone know how to accomplish this or any better solution?

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Hi @FBplus,

I haven’t seen any similar method or project in Playcanvas. Agreed it would be a good feature to have.

Here is the Three.js implementation, if anybody would like to give it a try:

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@Leonidas Hi Leonidas,Thanks for your reply
I’ve read that code and found this function:
https://github.com/mrdoob/three.js/blob/0950e5b6e8bceb520c154f45b5c240af45f0ed11/src/objects/Mesh.js#L438
I think the only thing I have to figure out may be the uv coordinates of each vertex
If I know the index of a triangle based on IndexBuffer,Is there anyway to get the uv coordinates of three vertices of that triangle?

There isn’t a Playcanvas built in method for that, but study the Three.js Triangle class to see the math behind it:

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@Leonidas I made it
I’ve created a test project base on this function and it works fine
https://playcanvas.com/project/704805/overview/paint-3d-test

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Wow @FBplus, that is working beautifully!! Many thanks for sharing.

I am going to definitely take a look at your implementation, this is quite useful for many things.

Nice work

We also have released a similar demo if both of you are interested: https://playcanvas.com/project/702588/overview/character-damage-demo

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@Leonidas I am so glad if you found this project useful
To be honest, I just copy and paste the code from threeJS with minor adjustments without considering the performance and there is still a lot to improve.

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Hello @FBplus and @Leonidas - I want to paint the back of a woman: https://playcanvas.com/editor/scene/1031376

• unfortunately, and no matter what I do, the brush only works on the top left area of my cutout back model?

As you can see; one of my workaround has been to alter this line in raycast.js:
`this.cameraEntity.camera.screenToWorld(screenPosition.x*3.6, screenPosition.y, this.cameraEntity.camera.farClip, this.ray.direction);`

(screenPosition.x multiplied by 3.6 in order to center the painted)

But otherwise, the problem of not being able to; paint blue on the whole area, still stands.

ok, got it working with a similar adjustment … don’t bother (nice example anyway @FBplus)

This example does not work anymore? Any updated on this subject?
Edit: Raycast does not return uv0 positions anymore I guess

There’s also this older and bit out of date PR that could be cleaned up and used I suspect

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Hello @yaustar . I forked your original Character damage demo but it isn’t working anymore in the latest version of playcanvas editor. Any ideas?

https://playcanvas.com/project/702588/overview/character-damage-demo

Thanks!

Unfortunately, we’ve removed that project from the tutorials as the developer who made it is on longer on our team and the project is no longer maintained.

Thanks for the update @yaustar

@mrkarate Found out someone has fixed the demo in a fork here: [SOLVED] Character damage demo broken in Engine v1.55 - #5 by devinhell

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That’s awesome!! thanks yaustar!!