koobas.hobune.stream
Vertices array in mesh vertices
Is there a specific way that unity adds vertices to the mesh.vertices array? Does it differ from mesh to mesh/program to program/ or is it just random altogether(or based on many variables)? I guess all the tools are there for me to determine that the index is of each vertex in a specific mesh, but if they are added to the array in a specifc order i can cut down uv/normal calculations(this would be very optimal if you can hint to how unity handles importing a meshes vertices).
Im still working out the whole uv/normal calc for each vertex using references here from other answers like: @bunny83 's post about http://answers.unity3d.com/questions/259127/does-anyone-have-any-code-to-subdivide-a-mesh-and.html>subdividing and @Statement 's post about http://answers.unity3d.com/questions/52728/fetching-triangles-from-a-3d-mesh.html>fetching triangles. I actually got inspired by Lasse 's answer to @Fattie 's question about finding http://answers.unity3d.com/questions/193695/in-unity-is-there-a-fast-way-to-find-nearby-triang.html>nearby triangles, which is basically exactly what i am doing. I want to set up a tree for an equal planes triangles(unitys built-in plane for now)(quadtree built from Start() ?) , i suppose thats the most relevant part of my question/inquiry other than order of vertices in the mesh.vertices array.
Sorry for the compacted question/answer post, hopefully it will inspire others as it has me. I look forward to your insight on this, ive been pondering this question for days now and just trying to figure out the best method before i type it all out(cuz ill probly get lazy and not continue research if i type it out first, at least 'til it becomes a problem :P).
"Is there a specific way that unity adds vertices to the mesh.vertices array"
Unity does not add the vertices: it would be like asking, "Why does microsoft word choose to write a particular type of novel?"
Furthermore, there is a deeper very important point to understand.
in 3D models generally (forget about unity, which is just a tool that USES 3D models), there is NO $$anonymous$$EANING or ORDER to the vertices.
Even very sophisticated programmers often do not understand this. Your question is a ver good one.
@fattie thanks, i appreciate this simple clarification. I kinda figured that at the very least a program like 3ds$$anonymous$$ax would somehow 'know' where the vertices are(order wise) so they can somehow be 'arranged' in an fbx export. But i suppose its more of a decipher job than an ordering job, which makes more sense from a program$$anonymous$$g standpoint. Thanks for that, im beginning to piece it together. It seems like the more time i spend, the easier a modeling programs functionality s become(other than well optimized procedures, which i suppose is...everything :X). Wish i knew that type of smarts right - now, lol. but dont we all... Thanks again.
it was incredibly bizarre to me when i started out that the 3D pipeline has no knowledge, at all, of tri positions. But, that's life!! again that other question linked to is basically a massive investigation of the issue "how to find nearby tris". really the answer is you just do it yourself.
some difficult issues arise conceptually, like, what do you "mean" by nearby, what if there's a very small gap, etc!
pls do not hesitate to up-thumb any long-winded answers that were helpful :-)
You have hit on an incredibly critical point here, jinx.
(1) Unity merely uses 3D models, it does not make or decide on them in any way.
It's important to note that even very sophisticated programmers often misunderstand this.
For example,
http://answers.unity3d.com/questions/193695/in-unity-is-there-a-fast-way-to-find-nearby-triang.html
Note that someone was saying: "It is an absolutely true statement that Unity shares vertices where it can. There is no situation where this is not true." ... that statement, is utterly incorrect.
but more importantly - the statement doesn't even make sense. It would be exactly like saying "Microsoft Word only produces crime novels where possible, it never produces action novels" It simply: makes no sense. You could MAYBE say something like "MAYA shares vertices where it can". (That claim would be totally incorrect and demonstrate a misunderstanding of 3D models.) But the sentence "UNITY shares vertices where it can" is just utterly meaningless - UNITY is to 3D models as your Laser Printer is to Novels. Your laser printer does not make any decisions on anything such as the plot or characters in your novel :-)
Moving on to the meat of your question.
(2) There is absolutely no - utterly no, whatoever - "rules" about vertex placement in 3D models.
it is very mportant to understand this, and again, even many sophisticated people do not understand this. People not unreasonably think that 3D models must "understand" surfaces, or that 3D models have verts in some arrangement. Again it is totally untrue.
You can read about this at vast length in the yellow comments on the images here
http://answers.unity3d.com/questions/193695/in-unity-is-there-a-fast-way-to-find-nearby-triang.html
Finally! the true meat of your question!! As you said I'm basically trying to create a quick reference for touching tris...
The answer is!
(3) Unfortunately - and very surprisingly - the 3D pipeline has absolutely, definitely, NO idea about the location of any triangles.
This was very surprising, incredibly surprising, to me when I first was fooling around w/ the 3D pipeline. But that's how it is. It all makes perfect sense when you get in to it. But the bottom line is, that is exactly what i was asking in this question, just like you "I'm bascially trying to create a quick reference for touching tris"
http://answers.unity3d.com/questions/193695/in-unity-is-there-a-fast-way-to-find-nearby-triang.html
So unfortunately the simple answer to your issue ("I'm bascially trying to create a quick reference for touching tris") is that you just have to, when you start up the app, look through the mesh and on your own, build a list (or whatever you want) with the information about touching tris.
Very simply, loop through each tri, look at each edge, and then loop through for a matching one. (again it is discussed at vast length in that other question!)
Hopefully this long-winded reply is of some value to you or others!! Cheers
Thanks! i appreciate you taking the time to explain this. I suppose it isnt as cut and dry as i had originally thought, but it isnt as bad as connecting a nuclear power plant to an outlet(just a guess :) ). Im just hoping it wont take too much to loop through all the given tris of a single mesh..obviously the more tris the more work, but as a general incentive im gonna test the average fps drop between 100 tris and maybe 1,000 or 10,000 to get an idea and set a warning limit/per resources available. I appreciate the help, im working on a procedural script which should be on the asset store within a cpl weeks...hopefully, though time seems to fly by these days. Ill let you, and all the others that helped me out know when its done so you can have fun testing it out if you so desire!
Read your question...in its entirety(man theres alot of back and forth and tons of comments), but i understand it much better looking at it with fresh wine soak-en eyes o_0. Any-who, im gonna give it my best shot in the A$$anonymous$$ and im sure ill get much more accomplished with the added support. Thanks again.
You will be pleased to hear, it is unbelievably fast to loo through the tris/verts like that looking for friends. it's one of those things where you worry about performance but it proves to be no problem.
I suppose, quite simply, it's just a blazingly fast native array (ie "some memory in a line") so it is damn fast.
typically it is something you do n start up, but it is so fast you could do it in realtime, really.
Don't forget too, you may well want to do it at BUILD TI$$anonymous$$E, and then the information is there locked in and you can just look it up instantly in a list or whatever.
Ask anything any time
There's no order other than what you supply. If you say "mesh.vertices = [Vector3(1, 1, 1), Vector3(2, 2, 2), Vector3(3, 3, 3), Vector3(4, 4, 4)];", then that's the order. If you're asking does Unity rearrange them for any reason, then no, it doesn't.
