Control a Marquee Selection through Script

Coding
1

Say I want to determine what, if any, components live at, or near, a specfic location in UV Space.
Can I perform a selection through python/API/mel/pymel given only a location and a shape node?

In psuedo code:

def getComponentAtLocation(shape=None, location=None, space=‘uv’, expand=None)
# pad the location with the expand amount to create a selection bounding box
# find any faces that cross the bounding box
# find any uv coordinates contained within the box
# return found components

getComponentAtLocation(shape=‘pSphereShape1’, location=[0.25, 0.75], space=‘uv’, expand=0.1)

Result: [‘pSphereShape1.f[2:5]’, ‘pSphereShape1.f[8]’, ‘pSphereShape1.map[4]’]

Thanks,

2

Just spit-balling here, but what about something like:

  • Get the uv bounding box for the query
  • Get all uvs on the object that fall within that boundingbox
  • Get all faces that are connected to those uvs

Would that give you what you wanted?

3

Something like this?

def getComponentAtLocation(shape=None, location=None, space='uv', expand=None):
    bb_min = location[0] - expand, location[1] - expand
    bb_max = location[0] + expand, location[1] + expand
    
    uv_coords = cmds.polyEditUV('%s.map[li]' % shape, q=True, u=True, v=True)
[/li]    uvs = []
    uv_num = 0
    for u, v in zip(*[iter(uv_coords)]*2):
        if u > bb_min[0] and u < bb_max[0] and v > bb_min[1] and v < bb_max[1]:
            uvs.append('%s.map[%d]' % (shape, uv_num))
        uv_num += 1

    faces = []
    if uvs:
        faces = cmds.polyListComponentConversion(uvs, fuv=True, tf=True)

    return faces, uvs
4

my first thought was to iterate over the uvs and test if the coordinates are inside the region. But i was hoping to avoid this route since it could be quite slow on large meshes/scenes.
I am hoping for some of function or node that wouldn’t need to iterate over the meshes.

5

Also, checking just the UV coordinates for inclusion with in the bounding region doesn’t find me polygons who cross the bounding region, but don’t contain any UVs with in it.

6

If you need to do poly-poly intersections look at GPC (there are python bindings in the cheeseshop) . This has C components so distribution may be tricky.

Planarhas a pure python version so it’s easy to package. It does not have a poly-poly intersection method. However you can use it to do half space tests and 2d - bounding box checks so it’s “easy” to make your own poly - poly intersection checker

7

thanks for the links!

8

I’d be curious to see what your solution ends up being if you feel like updating along the way.