Using ray casting to select faces

[LeonardMeagher2]

http://www.moczys.com/webGL/Experiment_02_V05.html

Being able to select a face from a mesh, or collision shape could be a useful feature in godot, in this example they change face color, but I could imagine using the face to get uv information which can turn to pixel information, and having the ability to move an image around in a 2d scene.

[TheoXD]

Use MeshDataTool to read faces and their vertices, and for each face run
var intersects = Geometry.ray_intersects_triangle( Vector3 from, Vector3 dir, Vector3 a, Vector3 b, Vector3 c )
and if you want the intersection point you create var plane = Plane(Vector3 a, Vector3 b, Vector3 c)
and check for the intersection point var co = plane.intersects_ray( Vector3 from, Vector3 dir )

[LeonardMeagher2]

so Geometry.ray_intersects_triangle is a Boolean, and plane.intersects_ray, is a Vector3?

[reduz]

The problem is that, on release, this information is not available, as not
stored in the server.

I was thinking of creating a node that holds geometry information in an
efficient way to allow for this kind of stuff, such as queries and
real-time decals.

On Tue, Sep 9, 2014 at 8:22 PM, Leonard Meagher notifications@github.com
wrote:

so Geometry.ray_intersects_triangle is a Boolean, and
plane.intersects_ray, is a Vector3?

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#684 (comment).

[LeonardMeagher2]

I like the sound of that haha.
@reduz

[bojidar-bg]

Shouldn't this be considered for 3.0?

[akien-mga]

What's the status on this for the upcoming 3.0 release?

[reduz]

There is TriangleMesh now, but it does not keep UV information. It's also mostly used for editing.
Kicking for 3.1

[akien-mga]

Moving to the next milestone as 3.1 is now feature frozen.

[LeonardMeagher2]

I don't think this a necessary feature anymore, it's easily solved many other ways.
Might open another issue or PR for exposing TriangleMesh functions to GDScript, but that's about it.

[idchlife]

So basically as of 2021 there is no built-in way as in Unity (RayCastHit.textureCoord) to get coordinate of texture to work with it etc?

I mean there are workarounds like shaders or manually iterating through every vertice but no easy way?

Asking because I came from Unity at some point and was utilizing .textureCoord heavily there. It seems Godot simply does not have such feature without modifying engine with some cpp plugins etc?

[leiget]

@idchlife
Yes it seems so, unfortunately. But Considering the 4.0 render API refactor, I imagine it'll eventually be on the list. Let's see if there is a issue/request for it in the tracker, and if not, then maybe we should make one.

[Calinou]

For the record, @leiget opened a proposal: godotengine/godot-proposals#2863