Add multi-select, specifier column, and visibility shortcuts to hierarchy panel

Ctrl+click toggles prim selection; Shift+click range-selects using a
per-frame visible-order list. Multi-selection is broadcast to the viewport
via a new SetOnPrimsSelected callback so Hydra highlights all selected prims.

Adds a 5th table column showing each prim's SdfSpecifier (def/over/class)
with colour coding. 'over' prims are shown in orange to make overrides
immediately visible.

Visibility icon updated: invisible prims show EyeSlash in orange instead
of grey. Ctrl+H / Shift+H keyboard shortcuts hide / show all selected prims.

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

src/ui/Application.cpp

@@ -115,6 +115,11 @@ bool Application::Initialize(const std::string& windowTitle, int width, int heig
             m_curveEditorPanel->SetSelectedPrimPath(path);
         });
 
+    m_sceneHierarchyPanel->SetOnPrimsSelected(
+        [this](const std::vector<std::string>& paths) {
+            m_viewportPanel->SetSelectedPrimPaths(paths);
+        });
+
     m_sceneHierarchyPanel->SetOnStageMetadataChanged(
         [this]() {
             RefreshManagers();

src/ui/SceneHierarchyPanel.cpp

@@ -86,9 +86,58 @@ void SceneHierarchyPanel::SetSelectedPathFromClick(const std::string& path) {
     m_primarySelectedPath = path;
     m_primarySdfPath      = path.empty() ? SdfPath() : SdfPath(path);
     if (!path.empty()) m_selectedPaths.insert(path);
-    // No scroll — user clicked the item directly, it's already visible.
+    if (!path.empty()) m_rangeAnchorPath = SdfPath(path);
     m_scrollToSelected = false;
-    if (m_onPrimSelected) m_onPrimSelected(path);
+    if (m_onPrimSelected)   m_onPrimSelected(path);
+    if (m_onPrimsSelected) {
+        std::vector<std::string> v;
+        if (!path.empty()) v.push_back(path);
+        m_onPrimsSelected(v);
+    }
+}
+
+void SceneHierarchyPanel::ToggleSelectionFromClick(const std::string& path) {
+    if (m_selectedPaths.count(path)) {
+        m_selectedPaths.erase(path);
+        if (m_primarySelectedPath == path) {
+            m_primarySelectedPath = m_selectedPaths.empty() ? "" : *m_selectedPaths.begin();
+            m_primarySdfPath = m_primarySelectedPath.empty()
+                ? SdfPath() : SdfPath(m_primarySelectedPath);
+        }
+    } else {
+        m_selectedPaths.insert(path);
+        m_primarySelectedPath = path;
+        m_primarySdfPath      = SdfPath(path);
+        m_rangeAnchorPath     = SdfPath(path);
+    }
+    m_scrollToSelected = false;
+    if (m_onPrimSelected) m_onPrimSelected(m_primarySelectedPath);
+    if (m_onPrimsSelected) {
+        std::vector<std::string> v(m_selectedPaths.begin(), m_selectedPaths.end());
+        m_onPrimsSelected(v);
+    }
+}
+
+void SceneHierarchyPanel::RangeSelectToPath(const SdfPath& path) {
+    auto it1 = std::find(m_visiblePrimOrder.begin(), m_visiblePrimOrder.end(), m_rangeAnchorPath);
+    auto it2 = std::find(m_visiblePrimOrder.begin(), m_visiblePrimOrder.end(), path);
+    if (it1 != m_visiblePrimOrder.end() && it2 != m_visiblePrimOrder.end()) {
+        int idx1 = static_cast<int>(it1 - m_visiblePrimOrder.begin());
+        int idx2 = static_cast<int>(it2 - m_visiblePrimOrder.begin());
+        if (idx1 > idx2) std::swap(idx1, idx2);
+        for (int i = idx1; i <= idx2; ++i)
+            m_selectedPaths.insert(m_visiblePrimOrder[i].GetString());
+    } else {
+        m_selectedPaths.insert(path.GetString());
+    }
+    m_primarySelectedPath = path.GetString();
+    m_primarySdfPath      = path;
+    m_scrollToSelected    = false;
+    if (m_onPrimSelected) m_onPrimSelected(m_primarySelectedPath);
+    if (m_onPrimsSelected) {
+        std::vector<std::string> v(m_selectedPaths.begin(), m_selectedPaths.end());
+        m_onPrimsSelected(v);
+    }
 }
 
 const char* SceneHierarchyPanel::GetPrimTypeIcon(const UsdPrim& prim) const {
@@ -185,6 +234,26 @@ void SceneHierarchyPanel::HandleKeyboardShortcuts() {
         SetSelectedPathFromClick(groupPath.GetString());
     }
 
+    // Ctrl+H — hide selected prims (visibility = invisible).
+    if (ImGui::GetIO().KeyCtrl && ImGui::IsKeyPressed(ImGuiKey_H, false) &&
+        !m_selectedPaths.empty() && m_stage) {
+        for (const auto& pathStr : m_selectedPaths) {
+            UsdPrim prim = m_stage->GetPrimAtPath(SdfPath(pathStr));
+            if (prim.IsValid() && prim.IsA<UsdGeomImageable>())
+                UsdGeomImageable(prim).GetVisibilityAttr().Set(UsdGeomTokens->invisible);
+        }
+    }
+
+    // Shift+H — show selected prims (visibility = inherited).
+    if (ImGui::GetIO().KeyShift && ImGui::IsKeyPressed(ImGuiKey_H, false) &&
+        !m_selectedPaths.empty() && m_stage) {
+        for (const auto& pathStr : m_selectedPaths) {
+            UsdPrim prim = m_stage->GetPrimAtPath(SdfPath(pathStr));
+            if (prim.IsValid() && prim.IsA<UsdGeomImageable>())
+                UsdGeomImageable(prim).GetVisibilityAttr().Set(UsdGeomTokens->inherited);
+        }
+    }
+
     // Delete — open the remove-prim confirmation modal.
     if (ImGui::IsKeyPressed(ImGuiKey_Delete, false) && !m_primarySdfPath.IsEmpty()) {
         auto rootLayer = m_stage->GetRootLayer();
@@ -266,6 +335,9 @@ void SceneHierarchyPanel::Render() {
     } else {
         UsdPrim root = m_stage->GetPseudoRoot();
 
+        // Rebuilt each frame as RenderPrimNode visits prims — used for range select.
+        m_visiblePrimOrder.clear();
+
         // Rebuild local-layer set once per frame (used by RenderPrimNode to
         // detect attribute overrides).  GetLayerStack() returns only the stage's
         // own layers — root layer, sublayers, session layer — NOT reference layers.
@@ -288,12 +360,14 @@ void SceneHierarchyPanel::Render() {
             ImGuiTableFlags_RowBg           |
             ImGuiTableFlags_SizingFixedFit;
 
-        if (ImGui::BeginTable("##primtree", 4, tblFlags)) {
+        const float kSpecW = ImGui::CalcTextSize("over").x + 2.f;
-            // Col 0 stretches; cols 1-3 are small fixed-width icon columns.
+        if (ImGui::BeginTable("##primtree", 5, tblFlags)) {
+            // Col 0 stretches; cols 1-4 are small fixed-width columns.
             ImGui::TableSetupColumn("##prim", ImGuiTableColumnFlags_WidthStretch);
             ImGui::TableSetupColumn("##type", ImGuiTableColumnFlags_WidthFixed, kIconW);
             ImGui::TableSetupColumn("##vis",  ImGuiTableColumnFlags_WidthFixed, kIconW);
             ImGui::TableSetupColumn("##ref",  ImGuiTableColumnFlags_WidthFixed, kIconW);
+            ImGui::TableSetupColumn("##spec", ImGuiTableColumnFlags_WidthFixed, kSpecW);
 
             for (const auto& child : root.GetChildren())
                 RenderPrimNode(child);
@@ -524,6 +598,7 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
     bool isInvisible = false;
     bool hasRefs     = prim.HasAuthoredReferences();
     bool hasChildren = !prim.GetChildren().empty();
+    SdfSpecifier spec = prim.GetSpecifier();
 
     if (isImageable) {
         UsdGeomImageable img(prim);
@@ -565,6 +640,7 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
     // ────────────────────────────────────────────────────────────────────────
 
     ImGui::TableNextRow();
+    m_visiblePrimOrder.push_back(primPath);  // for Shift+LMB range select
     ImGui::TableNextColumn();   // Col 0 — prim name + tree arrow
 
     ImGui::PushID(primStr.c_str());
@@ -642,6 +718,7 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
         ImGui::TableNextColumn();   // Col 1
         ImGui::TableNextColumn();   // Col 2
         ImGui::TableNextColumn();   // Col 3
+        ImGui::TableNextColumn();   // Col 4
         if (open && hasChildren)
             ImGui::TreePop();
         ImGui::PopID();
@@ -655,9 +732,16 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
     }
 
     if (!isRenaming) {
-        // Selection on click (not on toggle arrow).
+        // Selection on LMB click (not on toggle arrow).
-        if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen())
+        // Shift+LMB: range-select from anchor. Ctrl+LMB: toggle. Plain: replace.
-            SetSelectedPathFromClick(primStr);
+        if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen()) {
+            if (ImGui::GetIO().KeyShift)
+                RangeSelectToPath(primPath);
+            else if (ImGui::GetIO().KeyCtrl)
+                ToggleSelectionFromClick(primStr);
+            else
+                SetSelectedPathFromClick(primStr);
+        }
 
         // Double-click to start inline rename.
         if (ImGui::IsItemHovered() && ImGui::IsMouseDoubleClicked(ImGuiMouseButton_Left)) {
@@ -705,7 +789,7 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
             ImGui::EndDragDropTarget();
         }
 
-        // Context menu (must follow the last widget = the tree node).
+        // Context menu on RMB.
         RenderContextMenu(prim);
 
         // A context menu op (Unparent, Group, etc.) may have moved this prim,
@@ -714,6 +798,7 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
             ImGui::TableNextColumn();   // Col 1
             ImGui::TableNextColumn();   // Col 2
             ImGui::TableNextColumn();   // Col 3
+            ImGui::TableNextColumn();   // Col 4
             if (open && hasChildren)
                 ImGui::TreePop();
             ImGui::PopID();
@@ -740,8 +825,9 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
         const float  iconSz  = ImGui::GetTextLineHeight();
         const ImVec2 iconVec(iconSz, iconSz);
         Icon   visIcon = isInvisible ? Icon::EyeSlash : Icon::Eye;
-        ImVec4 visTint = isInvisible ? ImVec4(0.45f, 0.45f, 0.45f, 0.6f)
+        // Invisible: EyeSlash in orange; Visible: Eye at full alpha (dimmer tint).
-                                     : ImVec4(0.9f,  0.9f,  0.9f,  1.0f);
+        ImVec4 visTint = isInvisible ? ImVec4(1.00f, 0.60f, 0.15f, 1.0f)
+                                     : ImVec4(0.60f, 0.60f, 0.60f, 1.0f);
         ImTextureID id = m_iconManager ? m_iconManager->Get(visIcon) : ImTextureID_Invalid;
 
         ImGui::PushStyleColor(ImGuiCol_Button,        ImVec4(0,0,0,0));
@@ -750,7 +836,8 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
         ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0,0));
         ImGui::SetCursorPosX(ImGui::GetCursorPosX() + 1.f);
 
-        if (ImGui::ImageButton("##vis", ImTextureRef(id), iconVec,
+        std::string visId = "##vis_" + primStr;
+        if (ImGui::ImageButton(visId.c_str(), ImTextureRef(id), iconVec,
                                ImVec2(0,0), ImVec2(1,1), ImVec4(0,0,0,0), visTint)) {
             try {
                 UsdGeomImageable img(prim);
@@ -789,6 +876,28 @@ void SceneHierarchyPanel::RenderPrimNode(const UsdPrim& prim) {
             ImGui::SetTooltip("Has references");
     }
 
+    // ── Col 4: Specifier (def / over / class) ──────────────────────────────
+    ImGui::TableNextColumn();
+    {
+        const char* label = nullptr;
+        ImVec4      color;
+        switch (spec) {
+        case SdfSpecifierOver:
+            label = "over";
+            color = ImVec4(1.00f, 0.60f, 0.10f, isActive ? 1.0f : 0.45f);
+            break;
+        case SdfSpecifierClass:
+            label = "class";
+            color = ImVec4(0.40f, 0.70f, 1.00f, isActive ? 1.0f : 0.45f);
+            break;
+        default: // SdfSpecifierDef
+            label = "def";
+            color = ImVec4(0.45f, 0.45f, 0.45f, isActive ? 0.55f : 0.30f);
+            break;
+        }
+        ImGui::TextColored(color, "%s", label);
+    }
+
     // ── Recurse into children ───────────────────────────────────────────────
     // TreePop must be called in the SAME column as TreeNodeEx (col 0).
     // Since we called TableNextColumn three more times above, we must move

src/ui/SceneHierarchyPanel.h

@@ -1,4 +1,4 @@
-#pragma once
+#pragma once
 
 #include "../core/PropertyManager.h"
 #include "../core/CommandHistory.h"
@@ -62,6 +62,9 @@ public:
     using PrimSelectCallback = std::function<void(const std::string& path)>;
     void SetOnPrimSelected(PrimSelectCallback callback) { m_onPrimSelected = callback; }
 
+    using MultiPrimSelectCallback = std::function<void(const std::vector<std::string>&)>;
+    void SetOnPrimsSelected(MultiPrimSelectCallback cb) { m_onPrimsSelected = cb; }
+
     /// Called when stage-level metadata (e.g. up axis) is changed via the hierarchy panel.
     using StageMetadataChangedCallback = std::function<void()>;
     void SetOnStageMetadataChanged(StageMetadataChangedCallback callback) { m_onStageMetadataChanged = callback; }
@@ -96,7 +99,12 @@ private:
     /// NOT layers that came in through references or payloads.
     std::unordered_set<std::string> m_localLayers;
 
+    /// Visible prim order rebuilt each frame — used for Shift+RMB range select.
+    std::vector<pxr::SdfPath>        m_visiblePrimOrder;
+    pxr::SdfPath                     m_rangeAnchorPath;
+
     PrimSelectCallback           m_onPrimSelected;
+    MultiPrimSelectCallback      m_onPrimsSelected;
     StageMetadataChangedCallback m_onStageMetadataChanged;
 
     /// Remove-prim confirmation state.
@@ -121,6 +129,8 @@ private:
     bool                         m_renameJustStarted  = false;
 
     void         HandleKeyboardShortcuts();
+    void         ToggleSelectionFromClick(const std::string& path);
+    void         RangeSelectToPath(const pxr::SdfPath& path);
     SdfPath      FindUniqueChildPath(const SdfPath& parent, const std::string& baseName);
 };
 

src/ui/ViewportPanel.cpp

@@ -138,6 +138,17 @@ void ViewportPanel::SetSelectedPrimPath(const std::string& path)
     BroadcastSelection();
 }
 
+void ViewportPanel::SetSelectedPrimPaths(const std::vector<std::string>& paths)
+{
+    m_selectedSdfPaths.clear();
+    m_selectedPrimPath.clear();
+    for (const auto& p : paths)
+        m_selectedSdfPaths.push_back(pxr::SdfPath(p));
+    if (!paths.empty())
+        m_selectedPrimPath = paths.front();
+    BroadcastSelection();
+}
+
 // ---------------------------------------------------------------------------
 // Forwarding accessors
 // ---------------------------------------------------------------------------
@@ -384,7 +395,7 @@ void ViewportPanel::RenderGlobalLeftToolbar(ImVec2 contentPos, ImVec2 /*contentS
     const float kIconPad  =  5.0f;
     const float kRounding =  4.0f;
     const float kSpacing  =  3.0f;
-    const float kPadX     =  9.0f;  // left padding inside the strip
+    const float kPadX     =  4.0f;  // left padding inside the strip
     const float kPadY     = 10.0f;  // top padding
     const float kSepH     =  1.0f;  // separator line height
     const float kSepGap   =  6.0f;  // space around separator

src/ui/ViewportPanel.h

@@ -48,6 +48,8 @@ public:
     // ── Selection (called by SceneHierarchyPanel) ────────────────────────────
     /// Set a single selected prim (clears any multi-selection).
     void SetSelectedPrimPath(const std::string& path);
+    /// Set multiple selected prims (from hierarchy Ctrl+click multi-select).
+    void SetSelectedPrimPaths(const std::vector<std::string>& paths);
 
     // ── Main render (called from Application::RenderUI) ──────────────────────
     void Render(bool* p_open = nullptr);
@@ -99,7 +101,7 @@ private:
     bool IsMouseOverDivider(ImVec2 origin, ImVec2 total) const;
 
     /// Width (px) of the reserved left toolbar strip.
-    static constexpr float kToolbarW = 52.0f;
+    static constexpr float kToolbarW = 40.0f;
 
     // ── Selection management ─────────────────────────────────────────────────
     /// Push the current shared selection into every tile and the manipulator.