Angle and distance to connected verices


#1

propably easy, i wanna build a model of a 3d mesh in real. so i was thinking to connect pipes with balls,
by already knowing the angle and distance to the connected vertices. so i can put in the index and
have all the measurement available.

i know vertexbuffer a bit, but how do i know wich ones are connected? than i might be ready to do with myself


#2

the Index buffer contains the information of which vertices are connected with each other.
it defines the triangles by a sequence of integer numbers. 3 consecutive numbers represent the vertex indices of one triangle.


#3

hey Tonfilm,

i studied the vertex buffer node a bit, and i can see that each vertext appeares one time in the position XYZ pin. But i cant find these index buffer pin or node. If i would, i just could look for the appearence of the vertex to find all connections.

Another question, i actually use “distance” and “angle”, the angle node gives me 0 when the angle should be about “0,125”. ( image ) or it has some wierd orientation. This could also happened because i use a decompose transform node.


#4

of you want to have the position of a transformation then you need to do ApplyTransform (Vector) or * (3d) to take all transformations of the matrix into account.


#5

I hope i am not making a complete fool myselfe but the angle should be something close to 0.5 (“fully open” and assuming both vectors are on Z=0 but non of them is at 0,0,0) as with 3d vectors the angles usually limit to 0-0.5 and thats also the limit the formula inside the angle module calculates. This results from the angle beeing just a 2d angle between these vectors on their span plane, right?

see this video and especially from 6:30 how a span plane between 3d vectors looks like.

so this angle node might be not a good approach at all if i understand your question right.


#6

hey there,

thanks so far, i will study this quitely.

I still dont know how to find all vertices/triangles connected to a specific vertex.
The vertexbuffer(split) is what i studied, but i cant find a pin with id`s.

cheers


#7

it is the indices pin on the mesh split.


#8

well,

i am quite happy with the progress, here is some visulisation.
Almost there, in the best way i would use longitude and latitude for the angles,
would this be easier in vvvv with having the xyz values of two points?

Also i downloaded a stl file to try, they seem to have each triangle for its own.
So i need to prepare them in meshlab i guess, or having a routine in vvvv that checks for equal xyz vertice positions
and unify those together.

thanks so far


#10

okay,

i tried multiple meshes downloaded from the web.
Often the triangles are not connected.

So i need to find points sharing the same position i guess.
One vertice with xyz values, and a spread with of all vertices
with there xyz values.

if i simply use a “=” node,but i think it compares each value for its own.
So how could i check for a match of 3 following values.

cheers


#11

Just do AND (Spectral) with binsize 3 after =


#12

that worked perfectly. thanks so far.

another problem in this work seems, that each connection between two points
is there at least twice, because a -> b and b -> a.

seems simple to solve, i tried with the “=” node and could delete some, but its still to much.
would be really happy to get some help.

thx,ronny

lines.v4p (57.9 KB)


#13

Have a look at Occurrence (3d).


#14

woh, thats a huge one.

it helps me a lot on another issue, espaically the “first occurance” pin.

i still struggle to find not only same 3d positions, more to find a specific combination between two points.
so all lines that occure twice.


#15

i am thinking to combine the two positions to its center position, to then have only
one position i can work with. need to try at home…