Named Attribute node

docs/nodes/object_nodes/named_attribute.rst

@@ -0,0 +1,34 @@
+Named attribute
+===============
+
+Functionality
+-------------
+
+The node takes a blender object and an attribute name and tries to find
+attribute with such name if it fails it rises an error. The size and type
+of attributes remains unchanged by the node.
+
+Category
+--------
+
+BPY Data -> Set mesh attribute
+
+Inputs
+------
+
+- **Object** - Blender data blocks
+- **Name** - name of attribute to read
+
+Outputs
+-------
+
+- **Object** - Blender data blocks
+- **Attribute** - Values of the attriubte
+
+Usage
+-----
+
+Setting and reading some attribute on a mesh
+
+.. image:: https://user-images.githubusercontent.com/28003269/181222478-42302284-b72f-460d-9df2-6fed2b49f625.png
+   :width: 800px

docs/nodes/object_nodes/object_nodes_index.rst

@@ -20,3 +20,4 @@ Objects
    set_mesh_attribute
    set_collection
    copy_modifiers
+   named_attribute

index.md

@@ -642,6 +642,7 @@
     SvSortObjsNode
     SvFilterObjsNode
     SvSetMeshAttributeNode
+    SvNamedMeshAttributeNode
     SvPointOnMeshNodeMK2
     SvOBJRayCastNodeMK2
     SvSCNRayCastNodeMK2

nodes/object_nodes/named_attribute.py

@@ -0,0 +1,84 @@
+# This file is part of project Sverchok. It's copyrighted by the contributors
+# recorded in the version control history of the file, available from
+# its original location https://github.com/nortikin/sverchok/commit/master
+#
+# SPDX-License-Identifier: GPL3
+# License-Filename: LICENSE
+
+import numpy as np
+
+import bpy
+from sverchok.data_structure import fixed_iter
+from sverchok.node_tree import SverchCustomTreeNode
+
+
+def read_mesh_attribute(obj, name):
+    attr = obj.data.attributes[name]
+
+    if attr.data_type == 'FLOAT':
+        out = np.zeros(len(attr.data), dtype=np.float32)
+        attr.data.foreach_get('value', out)
+    elif attr.data_type == 'INT':
+        out = np.zeros(len(attr.data), dtype=int)
+        attr.data.foreach_get('value', out)
+    elif attr.data_type == 'BOOLEAN':
+        out = np.zeros(len(attr.data), dtype=bool)
+        attr.data.foreach_get('value', out)
+    elif attr.data_type == 'FLOAT_VECTOR':
+        out = np.zeros(len(attr.data) * 3, dtype=np.float32)
+        attr.data.foreach_get('vector', out)
+        out.shape = (-1, 3)
+    elif attr.data_type == 'FLOAT2':
+        out = np.zeros(len(attr.data) * 2, dtype=np.float32)
+        attr.data.foreach_get('vector', out)
+        out.shape = (-1, 2)
+    elif attr.data_type == 'FLOAT_COLOR':
+        out = np.zeros(len(attr.data) * 4, dtype=np.float32)
+        attr.data.foreach_get('color', out)
+        out.shape = (-1, 4)
+    elif attr.data_type == 'BYTE_COLOR':
+        # it seems blender keeps the values as floats internally
+        out = np.zeros(len(attr.data) * 4)
+        attr.data.foreach_get('color', out)
+        out *= 255
+        out = out.astype(np.uint8)
+        out.shape = (-1, 4)
+    else:
+        raise TypeError(f"Unknown {attr.data_type=}")
+    return out
+
+
+class SvNamedMeshAttributeNode(SverchCustomTreeNode, bpy.types.Node):
+    """
+    Triggers: object mesh
+    Tooltip: Reading mesh attribute
+    """
+    bl_idname = 'SvNamedMeshAttributeNode'
+    bl_label = 'Named Attribute'
+    bl_icon = 'SORTALPHA'
+
+    def sv_init(self, context):
+        self.inputs.new('SvObjectSocket', 'Object')
+        self.inputs.new('SvTextSocket', 'Name').use_prop = True
+        self.outputs.new('SvObjectSocket', "Object")
+        self.outputs.new('SvStringsSocket', "Attribute")
+
+    def process(self):
+        objs = self.inputs['Object'].sv_get(deepcopy=False, default=[])
+        names = self.inputs['Name'].sv_get(deepcopy=False)
+
+        attrs = []
+        names = fixed_iter(names, len(objs))
+        for obj, name in zip(objs, names):
+            name = name[0]
+            if name:
+                attrs.append(read_mesh_attribute(obj, name))
+            else:
+                attrs.append([])
+
+        self.outputs['Object'].sv_set(objs)
+        self.outputs['Attribute'].sv_set(attrs)
+
+
+register, unregister = bpy.utils.register_classes_factory(
+    [SvNamedMeshAttributeNode])