Select everything inside the UV 0-1

Question

I have a problem that I can't solve on my own. I want to select (or in my case deselect) everything that's inside the UV 0-1 space. I have a specific workflow that I follow and all my objects are placed in a number of UV quadrants. I want to select everything that's inside the first quadrant without selecting anything else.

The bpy.ops.uv.select lets you only select a single vertex located at the given coordinates, so that's the only workaround that I have at the moment, but this could be slow and, considering the following operations, is not really an option.

The other thing I looked at is the bpy.ops.uv.select_box. Unfortunately, this one works with mouse coordinates instead of 0-1 space coordinates which makes it totally useless.

I'm still looking but kind of running out of ideas.

Thank you in advance!

Answer 1

Have a look into the python templates that come along with Blender. There is an Operator Mesh UV template you can modify to your needs. Based on that, all you would have to figure out is how to set the select state of each UV vertex you're iterating on, by searching in the docs.

import bpy
import bmesh
def main(context):
    obj = context.active_object
    me = obj.data
    bm = bmesh.from_edit_mesh(me)
uv_layer = bm.loops.layers.uv.verify()

# adjust uv coordinates
for face in bm.faces:
    for loop in face.loops:
        loop_uv = loop[uv_layer]
        # Select UV vertex if in certain range
        if 0 <= loop_uv.uv.x <= 1 and 0 <= loop_uv.uv.y <= 1:
            loop_uv.select = True

bmesh.update_edit_mesh(me)



class UvOperator(bpy.types.Operator):
    """UV Operator description"""
    bl_idname = "uv.simple_operator"
    bl_label = "Simple UV Operator"
@classmethod
def poll(cls, context):
    obj = context.active_object
    return obj and obj.type == 'MESH' and obj.mode == 'EDIT'

def execute(self, context):
    main(context)
    return {'FINISHED'}



def register():
    bpy.utils.register_class(UvOperator)
def unregister():
    bpy.utils.unregister_class(UvOperator)
if name == "main":
    register()
# test call
bpy.ops.uv.simple_operator()

Performance: Using the bmesh method above takes 0.433614 seconds for a vertex count of 175,979 on my machine while iterating through the object data takes 1.514 seconds.

---

If you want to (de-)select the vertices of the actual mesh as well (keeping both in sync), you can set the selection state per vertex of the loop you are iterating on using BMVert.select_set() call:

Mesh vertices in Edit Mode (left), UV Vertices in the UV Editor (right)

class CUSTOM_OT_uvSelectBmesh(bpy.types.Operator):
    """Select UV and Mesh Vertices if in given range"""
    bl_idname = "uv.select_verts_bmesh"
    bl_label = "Select UV vertices (Bmesh)"
@classmethod
def poll(cls, context):
    obj = context.active_object
    return obj and obj.type == 'MESH' and obj.mode == 'EDIT'

def execute(self, context):
    min, max = (0.0, 1.0)

    obj = context.active_object
    me = obj.data
    bm = bmesh.from_edit_mesh(me)

    uv_layer = bm.loops.layers.uv.verify()
    for face in bm.faces:
        for loop in face.loops:
            loop_uv = loop[uv_layer]
            # Select UV vertex if in certain range
            if min <= loop_uv.uv.x <= max and min <= loop_uv.uv.y <= max:
                loop_uv.select = True
                loop.vert.select_set(True)
            else:
                loop.vert.select_set(False)

    bmesh.update_edit_mesh(me)
    return {'FINISHED'}

Performance: Selecting the UV vertices and the actual mesh vertices using the operator above takes 0.517211 seconds for a vertex count of 175,979 on my machine.

Answer 2

Via Select Box Operator

Example in blender version 2.91,2, after running script, adding Box Select operator with range options (arbitrarily labelled Select UV Image Bounds) to UV editors select menu.

AFAICT the select box operator uses normalized image 0-1 coordinates in the UV editor, as does the cursor, totally debunking this assertion in question.

Unfortunately, this one works with mouse coordinates instead of 0-1 space coordinates which makes it totally useless.

To which case can add the select box operator to a menu in the UV editor space, set the selection to our range and exec the operator so it does not wait for input via the UI.

Appended as choice Select UV Image Bounds in the select menu of UV / Image Editor.

import bpy
def draw(self, context):
    layout = self.layout
    layout.operator_context = 'EXEC_DEFAULT'
    op = layout.operator('uv.select_box', text="Select UV  Image Bounds")
    op.mode = 'SET'
    op.xmin = 0
    op.xmax = 1
op.ymin = 0
op.ymax = 1

op.wait_for_input = False
op.pinned = False


bpy.types.IMAGE_MT_select.append(draw)

PS May notice that in GIF some UV verts are shown selected outside the 0-1 range when in sync selection mode. This is because a vert can have many uvs (1 per loop) and need only one assoc. UV in range for all to be selected.

Via numpy

Run this script in object mode.

Can do this pretty quickly using the foreach_get and foreach_set methods to quickly get and set data.

import bpy
import numpy as np
ob = bpy.context.object
me = ob.data
uv_layer = me.uv_layers.active
get uv values
uvs = np.empty((2 * len(me.loops), 1))
uv_layer.data.foreach_get("uv", uvs)
select
u, v = uvs.reshape((-1, 2)).T
uv_layer.data.foreach_set(
        "select",
         np.logical_and(
            (u >= 0) & (u <= 1),
            (v >= 0) & (v <= 1)
            )
        )

PS. Relatively new to numpy. Feel there could be a quicker way still to create the True / False mask directly from uvs above. Please advise re any tips in this direction.