What does VertexHelper.GetUIVertexStream actually do

I'm looking at the documentation for this method: http://docs.unity3d.com/ScriptReference/UI.VertexHelper.GetUIVertexStream.html

The documentation is very short and says:

It is not really clear what this does, or why (and when) it should be used, can anyone please clarify ?

 

You can see the source in the UI Bitbucket.

All this function does is extract the UIVertext data from the mesh in to a copy List. Updating this list does not affect the base mesh.
So update the basemesh, you need to call VertextHelper.SetUIVertex(index)

If you want to pull out a single vertex and manipulate it, you need to use PopulateUIVertex to pull out the UIVertext info, then call SetUIVertex to update it.

It has been noted, that this constant rebuilding of the UI MESH is not the most performant thing, so some caching should be used. But without the patch or 5.3 UI source, it's not clear as to the best approach that is currently being used bu Unity.

 

Docs need improving.

 

Also need the source for the patch release, as the base 5.2.1 UI code there is soo out of date since the first patch release.

 

What is the relation between the number of vertices of the given mesh, and the amount of "UI vertices" returned in the list that is passed to this method?

Why Is the given text mesh constructed differently (e.g: different number of vertices) than what i'm getting back from this method ?

 

GetUIVertexStream takes a nice optimized mesh with shared verts and completely ruins it. Dont call it. Ever.

They should probably rename it GetUnoptimisedUIVertexStream() or GetBloatedUIVertexStream()

 

1-1.
A UIVertex is simple a struct made up of all the vertex information in a Mesh, from Vertices, normal's, colour, etc

Code (CSharp):

1.     public struct UIVertex
2.     {
3.         public static UIVertex simpleVert;
4.         public Color32 color;
5.         public Vector3 normal;
6.         public Vector3 position;
7.         public Vector4 tangent;
8.         public Vector2 uv0;
9.         public Vector2 uv1;
10.     }

These are just the mesh elements needed for UI.
Personally, I was happy with the last change which just used the base mesh and allowed uniform access to mesh data, the same as 3D stuff, but hay ho

 

It's useful if you want to loop through all the vertex information to make / set changes. In fact it's the only way now since they removed access to the base mesh (unless I missed something). you just cannot change anything through it.

 

If you do a GetUIVertexStream() and then a SetUIVertexStream() you will see exactly what it does...

 

100% agree.

UIVertex is just not required. UIVertexHelper is... pants.

 

While debugging, this doesn't look like the case:


After calling GetUIVertexStream these are the results:


The mesh has 28 vertices, while the list that was initialized contains 42 vertices. What could be the reason for this difference ?

 

Interesting, although that code is a little out of date, as the Patch release removed the mesh from scope and passes an instance of the VertexHelper now :S

Code (CSharp):

1. protected override void OnPopulateMesh(VertexHelper vh)

Your stats are interesting though, as if there is some optimization done in the conversion in to the UIVertex list.
Will have to test on 5.2.1P / 5.3 and see if the same is true.

 

How is that an optimization if there are more vertices? BTW i am on 5.2.1

 

It gives you back 6 verts per quad rather than 4 - as wikmanyo was alluding to the shared verts are no longer shared

 

That's what i was looking for. Understood now, thanks!

 

lol, I read it backwards #FaceSlap

 

Ah. So infuriating. Installed 5.2, updated a few scripts. And now it's all junk again, because I need to rewrite everything for the VertexHelper? Why Unity, Why?

 

i don't think it's such a big update to get it working...

 

If the vertexHelper documentation would be better, maybe

 

Doubt we'll see a doc update until 5.2.2 at the earliest

 

5.2.2 just came out today BTW

 

Yeah spotted that, AFTER I posted
Sadly the docs have NOT been updated (which is crazy) and the UI source still hasn't got any update.
@Tim C any update on when the docs for the changes since 5.2.1P1 or the source are likely to be available? We've been without accurate docs since the first patch release.

 

@SimonDarksideJ i think he said that he's no longer the UI lead (https://twitter.com/stramit/status/656721709756616704)

 

Darn it .
Ahh well, maybe @phil-Unity can chase
#SinkingShip?

 

That does explain things