Creating Mesh With Vertices And Connection Info

[amitc]

Folks,

I have 36,000 vertex positions, and I have their connectivity info for these vertices forming 66,000 triangles.
This will form a terrain. Since this is not on a regular grid its bit different then DEM's

Data looks something like
Vertex positions
x y z
3.0 2.0 1.0
3.0 4.5 1.0
.
.
.
so on 36,000 vertex

Triangles (Vertex connectivity)
0 1 3
4 6 5
.
.
.
so on 66,000 triangles

How do I go about creating this mesh?

I would also like to keep the vertex id as in data file as later on I'll be using this mesh as a soft body and deform it using synthetically created PDC cache files. (So the vertex id needs to be in particular order)

I can use polycreatfacet command to create triangles. But how do I create a mesh which is correctly stitched?
Again the vertex order needs to be preserved.

Any pointers appreciated.
Thanks
--Amit

[naughty]

Initially I thought, if it were me, I'd write a MEL script that read in your data file and constructed a mesh.. but then I couldn't think of how to get round the vertex Ids, and combining faces, etc, etc..

Then I just thought, why don't you just convert your original text data file into a Maya ASCII file and just open it in maya.

The MA format is pretty straightforward from what I can see, (from the point of view of a simple mesh) so you could probably even do it with a key-stoke macro in your text editor (if you have a decent one)

try creating a poly plane, triangulate it and delete all history. Select it and export selected as MA-SCII format. open this up into a text editor and have a look at it. it's not that different from the data you are starting with...

:nathaN

[user_deleted]

As said already several times, with such data the best is to create a model in OBJ file format.
Don't have the syntax with me, but it's a pretty simple one. Google for it ...

Guyb

[amitc]

QUOTE(guy_iti @ 02/02/06, 07:45 AM) [snapback]227116[/snapback]
As said already several times, with such data the best is to create a model in OBJ file format.
Don't have the syntax with me, but it's a pretty simple one. Google for it ...

Good you mentioned this I was thinking to open another thred on obj import
I did create an obj file the format is pretty simple just write vertex and faces on per line basis in ascii.
But Maya does not import it. Although in script editor the result of import is 1. No object is created no errors are printed out. Nothing happens. The vertex positions are in 600000 400.00 400000 range I wonder if this messes up Maya. A simple cube written out in obj is imported pretty well.

I would like to know the solution for this if it exists

QUOTE(Naughty @ 02/02/06, 01:02 AM) [snapback]227073[/snapback]
try creating a poly plane, triangulate it and delete all history. Select it and export selected as MA-SCII format. open this up into a text editor and have a look at it. it's not that different from the data you are starting with...

Aha, now that might work. Good thinking Naughty . Gonna give it a shot
Thanks
--Amit

[amitc]

OBJ Issue
I have found that maya does not like all types of OBJ's it likes vertex info as
V x y z w (where w is 1 for unstructured data)
.
.
. so on
F v1/vt1/vn1 v2/vt2/vn1 v3/vt3/vn3
.
.
. so on
(where v is vertex index, vt is vertex texture index and vn is vertex normal)
vt is optional but v and vn should be there else mesh is not generated so something like v//vn

Anyways I have gotten around it.
Now the trouble is the vertex order is messed up. Does any one know how to change vertex order or get it right to begin with?

Maya ascii Option
Looks like Maya uses mesh node to create a mesh
setAttr ".vt[start:end]" //vertex
setAttr ".ed[start:end]" //edges
setAttr ".n[start:end]" //normals
setAttr ".fc[start:end]" //faces

I have no idea how to set the edges. Any example of Mesh creation with Maya ascii would be very helpful.

It seems like I am hitting the wall here. Can someone please enlightne me how to work around this problem.
In the worst case I'll have to do comparisions of each mesh vertex with original data and find out the modified vertex index. This is a bad thing to do I guess.

Please Help!
Thanks
--Amit

[amitc]

More trouble with OBJ import.
Maya is eating(probably merging) 52 points from the obj model.
The triangle count remains correct. There are several duplicate vertices in the obj model.
Is there a way to avoid this?

I am still stuck on vertex ordering as well.

No luck in creating Maya ascii either. (not enough in documentation).
Very little help from reverse enginnering the files written out by maya.

Common guys give me a hand here.

--Amit

[joojaa]

Yes maya will allways reoragnize a obj file as it sees best fit to do!

the format is described in the api section. Atleast sortof.

[amitc]

QUOTE(Joojaa @ 02/03/06, 01:14 AM) [snapback]227203[/snapback]
the format is described in the api section. Atleast sortof.

Ya its minimal. More could have been helpful

QUOTE(Joojaa @ 02/03/06, 01:14 AM) [snapback]227203[/snapback]
Yes maya will allways reoragnize a obj file as it sees best fit to do!

Actually I just found out that the missing points in obj import are dangling vertices. They are not connected to anything. I guess Maya just ignores them.

Now only if someone can tell me how to reorder the mesh vertex id or atleast find the mapping.
I wrote a simple mel script checking the cooridnates with original data. I did not get much success with it.

--Amit

[joojaa]

QUOTE(amitc @ 02/03/06, 12:35 PM) [snapback]227210[/snapback]
Ya its minimal. More could have been helpful

well yes its spread a bit around in node refernce for mesh and MFnMesh api class. But thing is its the way most stuff in mayas documentted. Its also absolutely clear, what did you expect a tutorial or something.

Come on they are made by and for programmers. Whom we all know are as retarded as the guys shouting "I'm an artist I dont need to know this!" Besides all programmers know stuff like algebra and cryptic referencing because what works in one place must correlate to the hierarchy in another if not specified otherwise. This is result of how they minimize their own work so all programmers instinctively know all other programmers do this too.

[amitc]

QUOTE(amitc @ 02/03/06, 12:13 AM) [snapback]227196[/snapback]
I am still stuck on vertex ordering as well.

Sunit gave me a nice tip how to maintain tthe vertex ordering when importing obj files.

Look at the import options after importing any obj file.

under options set the set the multi object setting to false. (ie -mo 0)
By default this is on which cause changes in the vertex ordering.

Its funny I could not find any documentation for this option.

Hats off to Sunit

--Amit