Add Maya-style prim editing to SceneHierarchyPanel

- Inline rename: double-click prim label or F2 to edit name in-place;
  Enter commits, click-away or Esc cancels (undo-able)
- Drag-and-drop reparent: drag any prim onto another to make it a child;
  invisible root drop zone below tree to reparent to stage root (undo-able)
- Ctrl+G group: creates Xform group at common parent, reparents selection
  under it; filters descendant duplication; selects new group (undo-able)
- Delete key shortcut: opens existing remove-prim modal when panel focused
- Context menu: Rename (F2) and Group (Ctrl+G) items added
- Three new undo-able commands using UsdNamespaceEditor (USD 25.05):
  RenamePrimCommand, ReparentPrimCommand, GroupPrimsCommand

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ui/SceneHierarchyPanel.cpp

@@ -5,6 +5,9 @@
 #include "../core/commands/DeletePrimCommand.h"
 #include "../core/commands/AddReferenceCommand.h"
 #include "../core/commands/ReplaceReferenceCommand.h"
+#include "../core/commands/RenamePrimCommand.h"
+#include "../core/commands/ReparentPrimCommand.h"
+#include "../core/commands/GroupPrimsCommand.h"
 #include <pxr/usd/usd/prim.h>
 #include <pxr/usd/usd/primRange.h>
 #include <pxr/usd/usd/references.h>
@@ -118,12 +121,88 @@ Icon SceneHierarchyPanel::GetPrimTypeIconEnum(const UsdPrim& prim) const {
     return Icon::CircleDot;
 }
 
+SdfPath SceneHierarchyPanel::FindUniqueChildPath(const SdfPath& parent,
+                                                  const std::string& baseName) {
+    std::string name = baseName;
+    int n = 1;
+    while (m_stage->GetPrimAtPath(parent.AppendChild(TfToken(name))).IsValid())
+        name = baseName + "_" + std::to_string(n++);
+    return parent.AppendChild(TfToken(name));
+}
+
+void SceneHierarchyPanel::HandleKeyboardShortcuts() {
+    if (!ImGui::IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows)) return;
+    // Don't steal keys while any InputText (rename, arc modal, etc.) is active.
+    if (ImGui::GetIO().WantTextInput) return;
+
+    // F2 — start inline rename on the primary selection.
+    if (ImGui::IsKeyPressed(ImGuiKey_F2, false) && !m_primarySdfPath.IsEmpty()) {
+        UsdPrim prim = m_stage->GetPrimAtPath(m_primarySdfPath);
+        if (prim.IsValid()) {
+            m_renamingPath = m_primarySdfPath;
+            std::string name = prim.GetName().GetString();
+            strncpy(m_renameBuf, name.c_str(), sizeof(m_renameBuf) - 1);
+            m_renameBuf[sizeof(m_renameBuf) - 1] = '\0';
+            m_renameJustStarted = true;
+            m_scrollToSelected  = true; // ensure the prim is visible
+        }
+    }
+
+    // Ctrl+G — group selected prims under a new Xform.
+    if (ImGui::GetIO().KeyCtrl &&
+        ImGui::IsKeyPressed(ImGuiKey_G, false) &&
+        !m_selectedPaths.empty() && m_commandHistory && m_stage) {
+
+        std::vector<SdfPath> srcs;
+        for (const auto& s : m_selectedPaths)
+            srcs.emplace_back(s);
+
+        // Filter out paths that are descendants of other selected paths
+        // (they'll move with their ancestor, so grouping them separately is wrong).
+        std::vector<SdfPath> filtered;
+        for (const SdfPath& p : srcs) {
+            bool hasAncestorInSet = false;
+            for (const SdfPath& other : srcs) {
+                if (other != p && p.HasPrefix(other)) {
+                    hasAncestorInSet = true;
+                    break;
+                }
+            }
+            if (!hasAncestorInSet)
+                filtered.push_back(p);
+        }
+        if (filtered.empty()) return;
+
+        // Compute common parent of the filtered set.
+        SdfPath commonParent = filtered[0].GetParentPath();
+        for (const SdfPath& p : filtered) {
+            while (!p.HasPrefix(commonParent))
+                commonParent = commonParent.GetParentPath();
+        }
+
+        SdfPath groupPath = FindUniqueChildPath(commonParent, "group1");
+        m_commandHistory->Push(std::make_unique<GroupPrimsCommand>(m_stage, filtered, groupPath));
+        SetSelectedPathFromClick(groupPath.GetString());
+    }
+
+    // Delete — open the remove-prim confirmation modal.
+    if (ImGui::IsKeyPressed(ImGuiKey_Delete, false) && !m_primarySdfPath.IsEmpty()) {
+        auto rootLayer = m_stage->GetRootLayer();
+        if (rootLayer && !!rootLayer->GetPrimAtPath(m_primarySdfPath)) {
+            m_pendingRemovePrimPath = m_primarySdfPath;
+            m_showRemovePrimConfirm = true;
+        }
+    }
+}
+
 void SceneHierarchyPanel::Render() {
     if (!m_stage) {
         ImGui::TextDisabled("No stage loaded");
         return;
     }
 
+    HandleKeyboardShortcuts();
+
     // ── Edit-target layer switcher ────────────────────────────────────
     {
         struct LayerEntry { SdfLayerHandle layer; std::string label; };
@@ -222,6 +301,25 @@ void SceneHierarchyPanel::Render() {
             ImGui::EndTable();
         }
 
+        // ── Stage-root drop zone ───────────────────────────────────────────
+        // Invisible strip below the tree: drop here to reparent a prim to root.
+        ImGui::InvisibleButton("##rootdrop", ImVec2(-1.0f, 8.0f));
+        if (ImGui::BeginDragDropTarget()) {
+            if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload("USD_PRIM_PATH")) {
+                SdfPath srcPath(static_cast<const char*>(payload->Data));
+                // Only reparent if not already a root prim.
+                if (m_commandHistory && srcPath.GetPathElementCount() > 1) {
+                    std::string name = FindUniqueChildPath(SdfPath("/"), srcPath.GetName()).GetName();
+                    m_commandHistory->Push(std::make_unique<ReparentPrimCommand>(
+                        m_stage, srcPath, SdfPath("/"), name));
+                    SetSelectedPathFromClick(SdfPath("/").AppendChild(TfToken(name)).GetString());
+                }
+            }
+            ImGui::EndDragDropTarget();
+        }
+        if (ImGui::IsItemHovered())
+            ImGui::SetTooltip("Drop here to reparent to stage root");
+
         // Deselect when left-clicking on blank space (no prim item hovered).
         if (ImGui::IsWindowHovered(ImGuiHoveredFlags_RootAndChildWindows) &&
             ImGui::IsMouseClicked(ImGuiMouseButton_Left) &&
@@ -490,45 +588,111 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
         pushedColor = true;
     }
 
-    ImGuiTreeNodeFlags flags = ImGuiTreeNodeFlags_OpenOnArrow        |
-                               ImGuiTreeNodeFlags_OpenOnDoubleClick  |
-                               ImGuiTreeNodeFlags_SpanAllColumns;    // ← key: full-row item rect
-    if (isSelected)   flags |= ImGuiTreeNodeFlags_Selected;
-    if (!hasChildren) flags |= ImGuiTreeNodeFlags_Leaf |
-                               ImGuiTreeNodeFlags_NoTreePushOnOpen;
+    bool isRenaming = (m_renamingPath == primPath);
 
-    bool open = ImGui::TreeNodeEx(displayName.c_str(), flags);
+    ImGuiTreeNodeFlags flags = ImGuiTreeNodeFlags_OpenOnArrow |
+                               ImGuiTreeNodeFlags_SpanAllColumns;    // full-row item rect
+    if (!isRenaming)   flags |= ImGuiTreeNodeFlags_OpenOnDoubleClick;
+    if (isSelected)    flags |= ImGuiTreeNodeFlags_Selected;
+    if (!hasChildren)  flags |= ImGuiTreeNodeFlags_Leaf |
+                                ImGuiTreeNodeFlags_NoTreePushOnOpen;
 
-    if (pushedColor)
-        ImGui::PopStyleColor();
+    bool open = false;
+    if (isRenaming) {
+        // Render just the arrow (hidden label) so we keep indentation and open/close,
+        // then overlay an InputText inline for the prim name.
+        open = ImGui::TreeNodeEx("##renaming", flags);
+        if (pushedColor)
+            ImGui::PopStyleColor();
+        ImGui::SameLine();
+        ImGui::SetNextItemWidth(-1.0f);
+        if (m_renameJustStarted) {
+            ImGui::SetKeyboardFocusHere();
+            m_renameJustStarted = false;
+        }
+        bool commit = ImGui::InputText("##rename_input", m_renameBuf, sizeof(m_renameBuf),
+                                       ImGuiInputTextFlags_EnterReturnsTrue |
+                                       ImGuiInputTextFlags_AutoSelectAll);
+        bool canceled = ImGui::IsItemDeactivated() && !commit;
+        if (commit && m_renameBuf[0] != '\0') {
+            std::string newName = SanitizeUsdName(m_renameBuf);
+            if (!newName.empty() && newName != displayName && m_commandHistory) {
+                m_commandHistory->Push(std::make_unique<RenamePrimCommand>(
+                    m_stage, primPath, newName));
+                SdfPath newPath = primPath.GetParentPath().AppendChild(TfToken(newName));
+                SetSelectedPathFromClick(newPath.GetString());
+            }
+            m_renamingPath = SdfPath();
+        }
+        if (canceled)
+            m_renamingPath = SdfPath();
+    } else {
+        open = ImGui::TreeNodeEx(displayName.c_str(), flags);
+        if (pushedColor)
+            ImGui::PopStyleColor();
+    }
 
-    // ── Scroll-to-selection (now reliable: SpanAllColumns gives correct row rect) ──
+    // ── Scroll-to-selection (SpanAllColumns gives correct full-row rect) ────
     if (m_scrollToSelected && primStr == m_primarySelectedPath) {
         ImGui::SetScrollHereY(0.5f);
         m_scrollToSelected = false;
     }
 
-    // Selection on click (not on toggle arrow).
-    if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen())
-        SetSelectedPathFromClick(primStr);
+    if (!isRenaming) {
+        // Selection on click (not on toggle arrow).
+        if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen())
+            SetSelectedPathFromClick(primStr);
 
-    // Tooltip.
-    if (ImGui::IsItemHovered()) {
-        std::string tip = "Type: " + (typeName.empty() ? "(unknown)" : typeName) +
-                          "\nPath: " + primStr +
-                          "\nActive: " + (isActive ? "Yes" : "No");
-        if (isImageable)
-            tip += std::string("\nVisibility: ") + (isInvisible ? "Invisible" : "Visible");
-        if (hasRefs)
-            tip += "\nHas references";
-        if (m_selectedPaths.size() > 1)
-            tip += "\n\n" + std::to_string(m_selectedPaths.size()) + " prims selected";
-        ImGui::SetTooltip("%s", tip.c_str());
+        // Double-click to start inline rename.
+        if (ImGui::IsItemHovered() && ImGui::IsMouseDoubleClicked(ImGuiMouseButton_Left)) {
+            m_renamingPath = primPath;
+            strncpy(m_renameBuf, displayName.c_str(), sizeof(m_renameBuf) - 1);
+            m_renameBuf[sizeof(m_renameBuf) - 1] = '\0';
+            m_renameJustStarted = true;
+        }
+
+        // Tooltip.
+        if (ImGui::IsItemHovered()) {
+            std::string tip = "Type: " + (typeName.empty() ? "(unknown)" : typeName) +
+                              "\nPath: " + primStr +
+                              "\nActive: " + (isActive ? "Yes" : "No");
+            if (isImageable)
+                tip += std::string("\nVisibility: ") + (isInvisible ? "Invisible" : "Visible");
+            if (hasRefs)
+                tip += "\nHas references";
+            if (m_selectedPaths.size() > 1)
+                tip += "\n\n" + std::to_string(m_selectedPaths.size()) + " prims selected";
+            ImGui::SetTooltip("%s", tip.c_str());
+        }
+
+        // ── Drag-and-drop source ─────────────────────────────────────────
+        if (ImGui::BeginDragDropSource()) {
+            ImGui::SetDragDropPayload("USD_PRIM_PATH",
+                                      primStr.c_str(), primStr.size() + 1,
+                                      ImGuiCond_Once);
+            ImGui::Text("Move: %s", displayName.c_str());
+            ImGui::EndDragDropSource();
+        }
+
+        // ── Drag-and-drop target ─────────────────────────────────────────
+        if (ImGui::BeginDragDropTarget()) {
+            if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload("USD_PRIM_PATH")) {
+                SdfPath src(static_cast<const char*>(payload->Data));
+                // Guard: don't reparent onto self or onto a descendant.
+                if (src != primPath && !primPath.HasPrefix(src) && m_commandHistory) {
+                    std::string name = FindUniqueChildPath(primPath, src.GetName()).GetName();
+                    m_commandHistory->Push(std::make_unique<ReparentPrimCommand>(
+                        m_stage, src, primPath, name));
+                    SetSelectedPathFromClick(primPath.AppendChild(TfToken(name)).GetString());
+                }
+            }
+            ImGui::EndDragDropTarget();
+        }
+
+        // Context menu (must follow the last widget = the tree node).
+        RenderContextMenu(prim);
     }
 
-    // Context menu (must follow the last widget = the tree node).
-    RenderContextMenu(prim);
-
     // ── Col 1: Prim-type icon ───────────────────────────────────────────────
     ImGui::TableNextColumn();
     {
@@ -653,6 +817,43 @@ void SceneHierarchyPanel::RenderContextMenu(const UsdPrim& prim) {
 
         ImGui::Separator();
 
+        // ── Rename / Group ────────────────────────────────────────────────────
+        if (ImGui::MenuItem("Rename", "F2")) {
+            m_renamingPath = prim.GetPath();
+            std::string name = prim.GetName().GetString();
+            strncpy(m_renameBuf, name.c_str(), sizeof(m_renameBuf) - 1);
+            m_renameBuf[sizeof(m_renameBuf) - 1] = '\0';
+            m_renameJustStarted = true;
+            m_scrollToSelected  = true;
+        }
+        if (ImGui::MenuItem("Group", "Ctrl+G")) {
+            std::vector<SdfPath> srcs;
+            if (m_selectedPaths.count(prim.GetPath().GetString()))
+                for (const auto& s : m_selectedPaths) srcs.emplace_back(s);
+            else
+                srcs.push_back(prim.GetPath());
+            if (!srcs.empty() && m_commandHistory && m_stage) {
+                // Filter descendants
+                std::vector<SdfPath> filtered;
+                for (const SdfPath& p : srcs) {
+                    bool hasAncestor = false;
+                    for (const SdfPath& other : srcs)
+                        if (other != p && p.HasPrefix(other)) { hasAncestor = true; break; }
+                    if (!hasAncestor) filtered.push_back(p);
+                }
+                if (!filtered.empty()) {
+                    SdfPath commonParent = filtered[0].GetParentPath();
+                    for (const SdfPath& p : filtered)
+                        while (!p.HasPrefix(commonParent)) commonParent = commonParent.GetParentPath();
+                    SdfPath groupPath = FindUniqueChildPath(commonParent, "group1");
+                    m_commandHistory->Push(std::make_unique<GroupPrimsCommand>(m_stage, filtered, groupPath));
+                    SetSelectedPathFromClick(groupPath.GetString());
+                }
+            }
+        }
+
+        ImGui::Separator();
+
         bool hasChildren = !prim.GetChildren().empty();
         if (ImGui::MenuItem("Expand Children", nullptr, false, hasChildren)) {
             ImGui::GetStateStorage()->SetInt(ImGui::GetID(prim.GetPath().GetText()), 1);

src/ui/SceneHierarchyPanel.h

@@ -114,6 +114,14 @@ private:
     std::string                  m_arcModalVarSetName;
     char                         m_arcModalBuf[512]   = {};
     bool                         m_openArcModal       = false;
+
+    /// Inline rename state.
+    SdfPath                      m_renamingPath;          ///< non-empty while renaming
+    char                         m_renameBuf[256]     = {};
+    bool                         m_renameJustStarted  = false;
+
+    void         HandleKeyboardShortcuts();
+    SdfPath      FindUniqueChildPath(const SdfPath& parent, const std::string& baseName);
 };
 
 } // namespace UsdLayerManager