Hi,
I want to write a function that returns the uv coordinates of a specified mesh vertice. I read through the section “Understanding Texture Coordinates and Vertex Colors”, esp. the paragraph “Finding the corresponding vertices”:
In order to find out which texture vertex corresponds to a mesh vertex, you have to do the following:
- Take the index of the mesh vertex.
- Find out which faces reference the index of the face.
- Note the number of the vertex (1st, 2nd or 3rd – .x, .y or .z) inside each face.
- For each face referencing the vertex, get the texture face with the same index.
- Get the index of the respective texture vertex from the face – 1st, 2nd or 3rd / .x, .y or .z
- The vertex you got corresonds to the mesh vertex we started with.
- Repeat steps 3 to 6 for all faces found.
Same applies to color vertices.
So, my function looks like this:
-- Returns mapping coordinates of the indexed vertice in uv space
fn getUVCoordByVert theMesh mapChannel vertIndex = (
local faces = (meshOp.getFacesUsingVert theMesh vertIndex) as array -- All faces using this vertice
local vertices = (meshOp.getVertsUsingFace theMesh faces[1]) as array -- All vertices using the first face
local mapVertIndices = meshOp.getMapFace theMesh mapChannel faces[1] -- All map vertices using the same face in the same order
local mapVertIndex = -1
for i = 1 to vertices.count do (
if vertices[i] == vertIndex then (
mapVertIndex = mapVertIndices[i] as integer
)
)
return (meshOp.getMapVert theMesh mapChannel mapVertIndex) -- Return UV coordinates
)
But it doesn’t work very well because there are sometimes ambigous results in the getMapFace array and I’m not sure if I use them right.
Can somebody help me out?
Christian
This link can help you to understand the mapping coordinates.
You will probably have ideas by looking the functions of this script…
When I said “note the number inside the face – .x, .y, .z”, I REALLY meant the components of the face.
local faces = (meshOp.getFacesUsingVert theMesh vertIndex) as array
–returns an array of faces.
mapVertices = #() –init. an array to collect all map verts corresponding to vertIndex.
–Now for each face, use
for theFace in faces do
(
theFaceDef = getFace theMesh theFace
–theFaceDef will be a Point3 value where .x, .y and .z point at 3 vertices.
–Get the map face with the same index (theFace)
theMapFace = meshOp.getMapFace theMesh mapChannel theFace
–Now you can check which one of the 3 face’s vertices is the one you are looking for:
if theFaceDef.x == vertIndex then theMapVert = theMapFace.x as integer
if theFaceDef.y == vertIndex then theMapVert = theMapFace.y as integer
if theFaceDef.z == vertIndex then theMapVert = theMapFace.z as integer
–So at this point, theMapVert contains the index of a map vertex that corresponds
–to the verIndex parameter you passed to the function.
if findItem mapVertices theMapVert == 0 do
append mapVertices theMapVert –add to the array if not already there
)
–You repeat the same for all other faces and in the end,
–mapVertices will contain all map verts corresponding to your mesh vertex.
…
Here is the whole function:
fn getUVCoordByVert theMesh mapChannel vertIndex = (
local faces = (meshOp.getFacesUsingVert theMesh vertIndex) as array
mapVertices = #()
for theFace in faces do
(
theFaceDef = getFace theMesh theFace
theMapFace = meshOp.getMapFace theMesh mapChannel theFace
if theFaceDef.x == vertIndex then theMapVert = theMapFace.x as integer
if theFaceDef.y == vertIndex then theMapVert = theMapFace.y as integer
if theFaceDef.z == vertIndex then theMapVert = theMapFace.z as integer
if findItem mapVertices theMapVert == 0 do append mapVertices theMapVert
)
return mapVertices
)
getUVCoordByVert $ 1 1
Thank you both for helping me understand the whole topic better!
When I said “note the number inside the face – .x, .y, .z”, I REALLY meant the components of the face.
So you are one of the guys who wrote the 3d max help? You’ve done a great job, the 3ds max help is by far the best of all 3d applications I know!
Christian