Shifter: Chain Utils: Add locator removal and fix single locator add offset

docs/source/shifterUserDocumentation.rst

@@ -1592,7 +1592,7 @@ Hover over items to see detailed tooltips showing component names and additional
 Chain Utils
 ------------
 
-Chain Utils provides specialized tools for working with chain components (such as spine chains, tail chains, finger chains, etc.). It simplifies the process of extending chains by adding new locators.
+Chain Utils provides specialized tools for working with chain components (such as spine chains, tail chains, finger chains, etc.). It simplifies extending and shortening chains by adding or removing locators.
 
 .. image:: images/shifter/guide_utils/chain_utils.png
     :align: center
@@ -1608,6 +1608,14 @@ Extend an existing chain by adding a new locator at the end.
 - **Index Increment**: The new locator automatically receives the correct index number.
 - **Display Curve Update**: Connection curves are regenerated to include the new locator.
 
+**Remove Locator from Chain**
+
+Shorten an existing chain by removing its last locator.
+
+- **Minimum Length Guard**: At least one chain locator is always preserved.
+- **Child Guide Preservation**: Child component guides are moved to the new chain end.
+- **Display Curve Update**: Connection curves are regenerated after removal.
+
 **X-Ray Connection**
 
 For Maya 2022 and later, the tool automatically connects the ``guide_x_ray`` attribute to new locators, maintaining consistent X-ray visualization settings.
@@ -1621,8 +1629,8 @@ How to Use
 
 1. Select one or more chain guide roots in your scene.
 2. Open Chain Utils from **Shifter > Guide Utils > Chain Utils**.
-3. Click the button to add a locator to the selected chain(s).
-4. The new locator will appear at the end of each chain with proper positioning and naming.
+3. Click the add or remove button to modify the selected chain(s).
+4. The chain display curve will update to match the current locators.
 
 .. _bindplane-control-utils:
 

release/scripts/mgear/shifter/guide_tools/chain_utils.py

@@ -7,10 +7,11 @@
 from maya import cmds
 
 from mgear.vendor.Qt import QtWidgets
-from mgear.core import pyqt
 
 import mgear.pymaya as pm
 from mgear.core import icon
+from mgear.core import pyqt
+from mgear.core import utils
 
 
 # =============================================================================
@@ -143,14 +144,18 @@ def calculate_chain_offset(chain_end, chain_end_parent):
 
     Returns:
         list: [x, y, z] offset to apply to the new locator, or [0, 0, 0]
-            if no parent exists.
+            if no parent or component root exists.
     """
-    if chain_end_parent is None:
+    direction_source = chain_end_parent
+    if direction_source is None:
+        direction_source = find_component_root(chain_end)
+
+    if direction_source is None:
         return [0.0, 0.0, 0.0]
 
     # Get world positions
     end_pos = get_world_position(chain_end)
-    parent_pos = get_world_position(chain_end_parent)
+    parent_pos = get_world_position(direction_source)
 
     # Calculate direction vector (parent -> end)
     offset = [
@@ -426,10 +431,15 @@ def regenerate_display_curve(node):
         print("Warning: No mgear_curveCns found for: %s" % disp_curve)
         return None
 
-    # Collect all chain locators
+    # Collect the component root and all chain locators
+    # Component guides build display curves from the root followed by locators.
+    # Preserve that order so the root-to-first-locator segment is not lost
+    # during regeneration. A root + 1 locator is the minimum valid curve.
     locators = collect_chain_locators(node)
-    if len(locators) < 2:
-        print("Warning: Need at least 2 locators for display curve")
+    centers = [component_root]
+    centers.extend(locators)
+    if len(centers) < 2:
+        print("Warning: Need at least 2 centers for display curve")
         return None
 
     # Store curve properties before deleting
@@ -453,8 +463,8 @@ def regenerate_display_curve(node):
     cmds.delete(disp_curve)
 
     # Create new curve with updated locators using pymaya/icon
-    pm_locators = [pm.PyNode(loc) for loc in locators]
-    new_curve = icon.connection_display_curve(curve_name, pm_locators, degree)
+    pm_centers = [pm.PyNode(center) for center in centers]
+    new_curve = icon.connection_display_curve(curve_name, pm_centers, degree)
 
     # Restore line width
     if line_width >= 0:
@@ -571,6 +581,97 @@ def add_locator_to_chain(nodes=None):
     return results
 
 
+def remove_locator_from_chain(nodes=None):
+    """Remove the last locator from each selected chain.
+
+    The selected node may be anywhere in the chain. Child component guides
+    parented under the last locator are moved to the new chain end before the
+    display curve is regenerated. At least one chain locator is preserved.
+
+    Args:
+        nodes (list[str] or None): Nodes to process. If None, the current
+            selection (transforms) is used.
+
+    Returns:
+        list[tuple[str, str]]: List of (parent, removed_node) name pairs.
+
+    Raises:
+        RuntimeError: If no valid nodes are provided.
+    """
+    if nodes is None:
+        nodes = cmds.ls(sl=True, type="transform")
+        if nodes is None:
+            nodes = []
+
+    if not nodes:
+        raise RuntimeError("No transform selected or provided.")
+
+    results = []
+    processed_chains = set()
+
+    for node in nodes:
+        if not cmds.objExists(node):
+            print("Warning: node not found, skipping: %s" % node)
+            continue
+
+        chain_end, chain_end_parent = find_chain_end(node)
+        chain_locators = collect_chain_locators(chain_end)
+        if not chain_locators:
+            print("Warning: no chain locators found for: %s" % node)
+            continue
+
+        chain_key = chain_locators[0]
+        if chain_key in processed_chains:
+            continue
+        processed_chains.add(chain_key)
+
+        if len(chain_locators) <= 1 or chain_end_parent is None:
+            print(
+                "Warning: cannot remove '%s'. "
+                "At least one chain locator is required." % chain_end
+            )
+            continue
+
+        # Get the child guides
+        child_guides = []
+        children = cmds.listRelatives(
+            chain_end,
+            children=True,
+            type="transform",
+            fullPath=True,
+        )
+        if children is None:
+            children = []
+        for child in children:
+            if cmds.attributeQuery("isGearGuide", node=child, exists=True):
+                # temporarily parent the child guide to world space
+                unparented = cmds.parent(child, world=True)
+                if unparented:
+                    child_guides.append(unparented[0])
+
+        # Delete the chain end
+        removed_node = chain_end.split("|")[-1]
+        try:
+            cmds.delete(chain_end)
+        except Exception:
+            # If the deletion fails, parent the child guides back to the chain end
+            for child_guide in child_guides:
+                cmds.parent(child_guide, chain_end)
+            raise
+
+        for child_guide in child_guides:
+            cmds.parent(child_guide, chain_end_parent)
+
+        regenerate_display_curve(chain_end_parent)
+        results.append((chain_end_parent, removed_node))
+        print(
+            "Removed '%s' from chain (new end is '%s')"
+            % (removed_node, chain_end_parent)
+        )
+
+    return results
+
+
 # =============================================================================
 # UI Dialog
 # =============================================================================
@@ -603,27 +704,39 @@ def __init__(self, parent=None):
     def _create_widgets(self):
         """Create UI widgets."""
         self.add_locator_group = QtWidgets.QGroupBox("Add Locator to Chain")
+        self.remove_locator_group = QtWidgets.QGroupBox("Remove Locator from Chain")
 
         self.add_locator_btn = QtWidgets.QPushButton("Add Locator")
         self.add_locator_btn.setToolTip(
             "Add a new locator at the end of the selected chain.\n\n"
             "Select any locator in a chain - the new locator will be\n"
             "added at the end with the correct incremented index."
         )
+        self.remove_locator_btn = QtWidgets.QPushButton("Remove Locator")
+        self.remove_locator_btn.setToolTip(
+            "Remove the last locator from the selected chain.\n\n"
+            "Child component guides are moved to the new chain end.\n"
+            "At least one chain locator is preserved."
+        )
 
     def _create_layout(self):
         """Create UI layouts."""
         add_locator_layout = QtWidgets.QVBoxLayout(self.add_locator_group)
         add_locator_layout.addWidget(self.add_locator_btn)
+        remove_locator_layout = QtWidgets.QVBoxLayout(self.remove_locator_group)
+        remove_locator_layout.addWidget(self.remove_locator_btn)
 
         main_layout = QtWidgets.QVBoxLayout(self)
         main_layout.addWidget(self.add_locator_group)
+        main_layout.addWidget(self.remove_locator_group)
         main_layout.addStretch()
 
     def _create_connections(self):
         """Connect signals and slots."""
         self.add_locator_btn.clicked.connect(self._on_add_locator)
+        self.remove_locator_btn.clicked.connect(self._on_remove_locator)
 
+    @utils.one_undo
     def _on_add_locator(self):
         """Handle add locator button click."""
         try:
@@ -635,6 +748,18 @@ def _on_add_locator(self):
         except RuntimeError as exc:
             cmds.warning(str(exc))
 
+    @utils.one_undo
+    def _on_remove_locator(self):
+        """Handle remove locator button click."""
+        try:
+            results = remove_locator_from_chain()
+            if results:
+                # Select the newly end nodes
+                new_ends = [r[0] for r in results]
+                cmds.select(new_ends, r=True)
+        except RuntimeError as exc:
+            cmds.warning(str(exc))
+
 
 # =============================================================================
 # Entry Points