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Vlad
Vlad

Reputation: 77

how to find Y face of the cube in Maya with Python

sorry for such specific question guys , I think people only with knowledge of Maya will answer tho. In Maya I have cubes different sizes and I need to find with python which face of cube is pointing Y axis down. (Pivot is in center) Any tips will be appreciated

Thanks a lot :)

Upvotes: 1

Views: 983

Answers (3)

theodox
theodox

Reputation: 12218

If you just need a quick solution without vector math and Pymel or the the API, you can use cmds.polySelectConstraint to find the faces aligned with a normal. All you need to do is select all the faces, then use the constraint to get only the ones pointing the right way. This will select all the faces in a mesh that are pointing along a given axis:

import maya.cmds as cmds
def select_faces_by_axis (mesh, axis = (0,1,0), tolerance = 45):
    cmds.select(mesh + ".f[*]")
    cmds.polySelectConstraint(mode = 3, type = 8, orient = 2, orientaxis = axis, orientbound = (0, tolerance))
    cmds.polySelectConstraint(dis=True)  # remember to turn constraint off!

The axis is the x,y,z axis you want and tolerance is the slop in degrees you'll tolerate. To get the downward faces you'd do

select_faces_by_axis ('your_mesh_here', (0,0,-1))

or

select_faces_by_axis ('your_mesh_here', (0,0,-1), 1)  
# this would get faces only within 1 degree of downard

This method has the advantage of operating mostly in Maya's C++, it's going to be faster than python-based methods that loop over all the faces in a mesh.

Upvotes: 1

haggi krey
haggi krey

Reputation: 1978

With pymel the code can be a bit more compact. Selecting the faces pointing downwards:

n=pm.PyNode("pCubeShape1")
s = []
for f in n.faces:
    if f.getNormal(space='world')[1] < 0.0:
        s.append(f)
pm.select(s)

Upvotes: 1

ababak
ababak

Reputation: 1803

import re
from maya import cmds
from pymel.core.datatypes import Vector, Matrix, Point

obj = 'pCube1'
# Get the world transformation matrix of the object
obj_matrix = Matrix(cmds.xform(obj, query=True, worldSpace=True, matrix=True))
# Iterate through all faces
for face in cmds.ls(obj + '.f[*]', flatten=True):
    # Get face normal in object space
    face_normals_text = cmds.polyInfo(face, faceNormals=True)[0]
    # Convert to a list of floats
    face_normals = [float(digit) for digit in re.findall(r'-?\d*\.\d*', face_normals_text)]
    # Create a Vector object and multiply with matrix to get world space
    v = Vector(face_normals) * obj_matrix
    # Check if vector faces downwards
    if max(abs(v[0]), abs(v[1]), abs(v[2])) == -v[1]:
        print face, v

Upvotes: 3

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