Programatically specify the input group behaviour at the modifier panel

[rsaccon]

When directly editing nodes, there is the Group Input Panel to specify Input Default, Min, Max and more, see screenshot below. But with Geometry Script what I have found out so far, only Default can be set. Is there a way to programatically set the other fields from that panel ? For numbers it would be great to be able to specify Min and Max

[carson-katri]

An implementation was started, but not completed here:

geometry-script/api/types.py

Lines 35 to 39 in da99654

	for s in filter(lambda x: isinstance(x, slice), args):
	if (isinstance(s.start, float) or isinstance(s.start, int)) and (isinstance(s.stop, float) or isinstance(s.stop, int)):
	print(f"minmax: ({s.start}, {s.stop})")
	elif isinstance(s.start, str):
	print(f"{s.start} = {s.stop}")

It would allow you to write something like this:

def min_max_demo(value: Int[slice(0, 1)]):
    pass

It's just a matter of completing the implementation.

[carson-katri]

The API should probably be extended to support more options:

def test(value: Int[0, 1]): pass # min, max
def test(value: Int["My Value"]): pass # custom input name
def test(value: Int[InputOptions(min=0, max=1, tooltip="The value you want", ...)]): pass # full-featured configuration

Alternatively, wrapper types could be used. I find this is a bit more confusing to read though:

def test(value: MinMax[Int, 0, 1]): pass
def test(value: Named[Int, "My Value"]): pass
def test(value: Tooltip[MinMax[Int, 0, 1], "The value you want"]): pass

[rsaccon]

Great, thanks, so this will be coming eventually ...

[rsaccon]

I started looking at the source code, in order to try to complete the implementation. But I have a question regarding the missing parts of the implementation. I see at several places in the code base that a value gets assigned to the default_value attribute of an input node. Now I assume at those places also start and stop attributes need to be set for min and max. And the same or similar for custom input name, tooltip, etc. Does that make sense ?

[rsaccon]

Got one microstep further in understanding things. Could not find any attributes at he output sockets of the input group which suggest they serve to set min and max. These are the attributes for an example input socket I played with (as learning exercise for later actually setting the options via geometry script):

['__doc__', '__module__', '__slots__', 'bl_idname', 'bl_label', 'bl_rna', 'bl_subtype_label', 'default_value', 'description', 'display_shape', 'draw', 'draw_color', 'enabled', 'hide', 'hide_value', 'identifier', 'is_linked', 'is_multi_input', 'is_output', 'is_unavailable', 'label', 'link_limit', 'name', 'node', 'rna_type', 'show_expanded', 'type']

I can set visually in the UI things like default, bl_subtype_label and I can retrieve those those attributes in Python by walking the node tree and checking the links between the nodes. But there is nothing there for setting min and max. Anything obvious I am missing ?

[BradyAJohnston]

@rsaccon the min and max have to be set via the interface.items_tree for the node group, and not the output sockets for the Group Input.

node_group = bpy.data.node_groups['my_node']
node_group.interface.items_tree["Value"].default_value = 1
node_group.interface.items_tree["Value"].min_value = 1
node_group.interface.items_tree["Value"].max_value = 0

[rsaccon]

@BradyAJohnston That really helped. Thanks a lot.

[rsaccon]

After trying to halfway understand what is going on under the hood at Geometry Script, I managed to implement min and max input options at my fork. The API looks like this right now:

 # min
def test(value: Int[0]): pass
def test(value: Float[0.0]): pass

# min, max
def test(value: Int[0, 1]): pass
def test(value: Float[0.0, 1.0]): pass

# min, max (slice notation)
def test(value: Int[0:1]): pass
def test(value: Float[0.0:1.0]): pass

Before making a PR I want to test some more edge cases and properly handle them. And extend with an InputOption class to allow additional input options (subtype, custom-name, tooltip and hide-in-modifier).

[rsaccon]

Now I got stuck with trying to set the input subtype (such as Distance, Percentage, etc). While it is straight forward to set name, default, min, max and tooltip just by setting the proper input socket attribute, for the subtype it seems an operator needs to be called (just setting the attribute only changes the selector label but not the value). If I do it by hand in the Node UI, then this shows up in the console log:

bpy.ops.node.tree_socket_change_subtype(socket_subtype='DISTANCE')

so I try to do it programmatically in the console and it fails:

>>> bpy.ops.node.tree_socket_change_subtype(socket_subtype='DISTANCE')
...
Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
  File "/Applications/Blender36.app/Contents/Resources/3.6/scripts/modules/bpy/ops.py", line 113, in __call__
    ret = _op_call(self.idname_py(), None, kw)
RuntimeError: Operator bpy.ops.node.tree_socket_change_subtype.poll() failed, context is incorrect

next I try set the context. After taking a look at the node input options UI source code, I come up with another failed attempt:

>>> active_socket = bpy.data.node_groups['example'].inputs[0]
>>> context_override = bpy.context.copy()
>>> context_override["interface_socket"] = active_socket
>>> with bpy.context.temp_override(**context_override):
...     bpy.ops.node.tree_socket_change_subtype(socket_subtype='DISTANCE')
... 
Traceback (most recent call last):
  File "<blender_console>", line 2, in <module>
  File "/Applications/Blender36.app/Contents/Resources/3.6/scripts/modules/bpy/ops.py", line 113, in __call__
    ret = _op_call(self.idname_py(), None, kw)
RuntimeError: Operator bpy.ops.node.tree_socket_change_subtype.poll() failed, context is incorrect

So how do I set the right context ??? The second attempt failed because there is no interface_socket in bpy.context. But what context do I have to set ? Or is there a different way to set programmatically the input subtype ?

[rsaccon]

I did another attempt and I finally managed to change the input subtype (just in the python console for now), but there is still a context error:

>>> active_socket = bpy.data.node_groups['experiment'].inputs[3]
>>> for area in bpy.context.screen.areas:
...     for space in area.spaces:
...         if space.type == 'NODE_EDITOR':
...             with bpy.context.temp_override(area=area, space=space, interface_socket=active_socket):
...                 bpy.ops.node.tree_socket_change_subtype('INVOKE_DEFAULT', socket_subtype='DISTANCE')
...                 break
... 
{'FINISHED'}

Traceback (most recent call last):
  File "<blender_console>", line 7, in <module>
  File "/Applications/Blender36.app/Contents/Resources/3.6/scripts/modules/bpy/ops.py", line 111, in __call__
    ret = _op_call(self.idname_py(), C_dict, kw, C_exec, C_undo)
RuntimeError: Operator bpy.ops.node.tree_socket_change_subtype.poll() failed, context is incorrect

here is the poll source code of the tree_socket_change_subtype operator:
https://github.com/blender/blender/blob/c7fc78b81ecb8beb332d064f572d8e2ed9219717/source/blender/editors/space_node/node_edit.cc#L2501-L2513

I don't know what is causing that exception. Maybe my approach to set the context is wrong.

Anyway, I will continue now to implement this input options in my fork, for vectors as well.

[rsaccon]

My suggested solution for this issue is in this PR, so closing this.