Docking: Reworked SetNextWindowUserType() as SetNextWindowDockFamily(), allowing multiple scene to be tagged with their scene id and not receive tabs from other scene + persistent storage for family id to allow for docking tree fork/remap.

imgui.cpp

@@ -2371,7 +2371,6 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
     HiddenFramesRegular = HiddenFramesForResize = 0;
     SetWindowPosAllowFlags = SetWindowSizeAllowFlags = SetWindowCollapsedAllowFlags = SetWindowDockAllowFlags = ImGuiCond_Always | ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing;
     SetWindowPosVal = SetWindowPosPivot = ImVec2(FLT_MAX, FLT_MAX);
-    UserTypeId = 0;
 
     LastFrameActive = -1;
     ItemWidthDefault = 0.0f;
@@ -4969,7 +4968,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     {
         window->SizeContentsExplicit = ImVec2(0.0f, 0.0f);
     }
-    window->UserTypeId = g.NextWindowData.UserTypeId;
+    window->DockFamily = g.NextWindowData.DockFamily;
     if (g.NextWindowData.CollapsedCond)
         SetWindowCollapsed(window, g.NextWindowData.CollapsedVal, g.NextWindowData.CollapsedCond);
     if (g.NextWindowData.FocusCond)
@@ -6357,10 +6356,10 @@ void ImGui::SetNextWindowDock(ImGuiID id, ImGuiCond cond)
     g.NextWindowData.DockId = id;
 }
 
-void ImGui::SetNextWindowUserType(ImGuiID user_type)
+void ImGui::SetNextWindowDockFamily(const ImGuiDockFamily* family)
 {
     ImGuiContext& g = *GImGui;
-    g.NextWindowData.UserTypeId = user_type;
+    g.NextWindowData.DockFamily = *family;
 }
 
 // In window space (not screen space!)
@@ -10178,19 +10177,19 @@ void ImGui::DockContextProcessUndockNode(ImGuiContext* ctx, ImGuiDockNode* node)
 ImGuiDockNode::ImGuiDockNode(ImGuiID id)
 {
     ID = id;
-    UserTypeIdFilter = 0;
     Flags = 0;
     ParentNode = ChildNodes[0] = ChildNodes[1] = NULL;
     TabBar = NULL;
     SplitAxis = ImGuiAxis_None;
+
     HostWindow = VisibleWindow = NULL;
     OnlyNodeWithWindows = NULL;
     LastFrameAlive = LastFrameActive = -1;
     LastFocusedNodeID = 0;
     SelectedTabID = 0;
     WantCloseTabID = 0;
-    IsVisible = true;
     InitFromFirstWindowPosSize = InitFromFirstWindowViewport = false;
+    IsVisible = true;
     IsDockSpace = IsDocumentRoot = HasCloseButton = HasCollapseButton = WantCloseAll = WantLockSizeOnce = WantMouseMove = false;
 }
 
@@ -10493,9 +10492,18 @@ static void ImGui::DockNodeUpdate(ImGuiDockNode* node)
             DockNodeUpdateFindOnlyNodeWithWindowsRec(node, &count, &first_node_with_windows);
             node->OnlyNodeWithWindows = (count == 1 ? first_node_with_windows : NULL);
 
-            // Copy the user type from _any_ of our window so it can be used for proper dock filtering.
+            // Copy the dock family from of our window so it can be used for proper dock filtering.
+            // When node has mixed windows, prioritize the family with the most constraint (CompatibleWithNeutral = false) as the reference to copy.
             if (first_node_with_windows)
-                node->UserTypeIdFilter = first_node_with_windows->Windows[0]->UserTypeId;
+            {
+                node->DockFamily = first_node_with_windows->Windows[0]->DockFamily;
+                for (int n = 1; n < first_node_with_windows->Windows.Size; n++)
+                    if (first_node_with_windows->Windows[n]->DockFamily.CompatibleWithFamilyZero == false)
+                    {
+                        node->DockFamily = first_node_with_windows->Windows[n]->DockFamily;
+                        break;
+                    }
+            }
         }
     }
 
@@ -10863,9 +10871,16 @@ static bool DockNodeIsDropAllowedOne(ImGuiWindow* payload, ImGuiWindow* host_win
     if ((host_window->Flags & ImGuiWindowFlags_DockNodeHost) && host_window->DockNodeAsHost->IsDockSpace && payload->BeginOrderWithinContext < host_window->BeginOrderWithinContext)
         return false;
 
-    ImGuiID host_user_type_id = host_window->DockNodeAsHost ? host_window->DockNodeAsHost->UserTypeIdFilter : host_window->UserTypeId;
+    ImGuiDockFamily* host_family = host_window->DockNodeAsHost ? &host_window->DockNodeAsHost->DockFamily : &host_window->DockFamily;
-    if (payload->UserTypeId != host_user_type_id)
+    ImGuiDockFamily* payload_family = &payload->DockFamily;
+    if (host_family->FamilyId != payload_family->FamilyId)
+    {
+        if (host_family->FamilyId != 0 && host_family->CompatibleWithFamilyZero && payload_family->FamilyId == 0)
+            return true;
+        if (payload_family->FamilyId != 0 && payload_family->CompatibleWithFamilyZero && host_family->FamilyId == 0)
+            return true;
         return false;
+    }
 
     return true;
 }
@@ -11443,7 +11458,7 @@ void ImGui::SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond)
 
 // Create an explicit dockspace node within an existing window. Also expose dock node flags and creates a DocumentRoot node by default.
 // The DocumentRoot node is always displayed even when empty and shrink/extend according to the requested size of its neighbors.
-void ImGui::DockSpace(ImGuiID id, const ImVec2& size_arg, ImGuiDockNodeFlags dock_space_flags, ImGuiID user_type_filter)
+void ImGui::DockSpace(ImGuiID id, const ImVec2& size_arg, ImGuiDockNodeFlags dock_space_flags, const ImGuiDockFamily* dock_family)
 {
     ImGuiContext* ctx = GImGui;
     ImGuiContext& g = *ctx;
@@ -11456,7 +11471,7 @@ void ImGui::DockSpace(ImGuiID id, const ImVec2& size_arg, ImGuiDockNodeFlags doc
         node->IsDocumentRoot = true;
     }
     node->Flags = dock_space_flags;
-    node->UserTypeIdFilter = user_type_filter;
+    node->DockFamily = dock_family ? *dock_family : ImGuiDockFamily();
 
     // When a Dockspace transitioned form implicit to explicit this may be called a second time
     // It is possible that the node has already been claimed by a docked window which appeared before the DockSpace() node, so we overwrite IsDockSpace again.
@@ -12391,6 +12406,7 @@ static void SettingsHandlerWindow_ReadLine(ImGuiContext*, ImGuiSettingsHandler*,
     else if (sscanf(line, "Collapsed=%d", &i) == 1)             { settings->Collapsed = (i != 0); }
     else if (sscanf(line, "DockId=0x%X,%d", &u1, &i) == 2)      { settings->DockId = u1; settings->DockOrder = (short)i; }
     else if (sscanf(line, "DockId=0x%X", &u1) == 1)             { settings->DockId = u1; settings->DockOrder = -1; }
+    else if (sscanf(line, "DockFamilyId=0x%X", &u1) == 1)       { settings->DockFamilyId = u1; }
 }
 
 static void SettingsHandlerWindow_WriteAll(ImGuiContext* imgui_ctx, ImGuiSettingsHandler* handler, ImGuiTextBuffer* buf)
@@ -12419,6 +12435,7 @@ static void SettingsHandlerWindow_WriteAll(ImGuiContext* imgui_ctx, ImGuiSetting
         settings->ViewportPos = window->ViewportPos;
         IM_ASSERT(window->DockNode == NULL || window->DockNode->ID == window->DockId);
         settings->DockId = window->DockId;
+        settings->DockFamilyId = window->DockFamily.FamilyId;
         settings->DockOrder = window->DockOrder;
         settings->Collapsed = window->Collapsed;
     }
@@ -12449,6 +12466,8 @@ static void SettingsHandlerWindow_WriteAll(ImGuiContext* imgui_ctx, ImGuiSetting
                 buf->appendf("DockId=0x%08X\n", settings->DockId);
             else
                 buf->appendf("DockId=0x%08X,%d\n", settings->DockId, settings->DockOrder);
+            if (settings->DockFamilyId != 0)
+                buf->appendf("DockFamilyId=0x%08X\n", settings->DockFamilyId);
         }
         buf->appendf("\n");
     }

imgui.h

@@ -77,6 +77,7 @@ struct ImColor;                     // Helper functions to create a color that c
 typedef void* ImTextureID;          // User data to identify a texture (this is whatever to you want it to be! read the FAQ about ImTextureID in imgui.cpp)
 #endif
 struct ImGuiContext;                // ImGui context (opaque)
+struct ImGuiDockFamily;             // Docking family for dock filtering
 struct ImGuiIO;                     // Main configuration and I/O between your application and ImGui
 struct ImGuiInputTextCallbackData;  // Shared state of InputText() when using custom ImGuiInputTextCallback (rare/advanced use)
 struct ImGuiListClipper;            // Helper to manually clip large list of items
@@ -519,9 +520,9 @@ namespace ImGui
     // [BETA API] Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable.
     // Note: you DO NOT need to call DockSpace() to use most Docking facilities! You can hold SHIFT anywhere while moving windows. 
     // Use DockSpace() to create an explicit dock node _within_ an existing window. See Docking demo for details.
-    IMGUI_API void          DockSpace(ImGuiID id, const ImVec2& size = ImVec2(0, 0), ImGuiDockNodeFlags flags = 0, ImGuiID user_type_filter = 0);
+    IMGUI_API void          DockSpace(ImGuiID id, const ImVec2& size = ImVec2(0, 0), ImGuiDockNodeFlags flags = 0, const ImGuiDockFamily* dock_family = NULL);
     IMGUI_API void          SetNextWindowDock(ImGuiID dock_id, ImGuiCond cond = 0);             // set next window dock id (FIXME-DOCK)
-    IMGUI_API void          SetNextWindowUserType(ImGuiID user_type);                           // FIXME-DOCK: set next window user type (docking filters by same user_type)
+    IMGUI_API void          SetNextWindowDockFamily(const ImGuiDockFamily* dock_family);        // FIXME-DOCK: set next window user type (docking filters by same user_type)
     IMGUI_API bool          IsWindowDocked();                                                   // is current window docked into another window? 
 
     // Logging/Capture: all text output from interface is captured to tty/file/clipboard. By default, tree nodes are automatically opened during logging.
@@ -1563,6 +1564,15 @@ struct ImGuiSizeCallbackData
     ImVec2  DesiredSize;    // Read-write.  Desired size, based on user's mouse position. Write to this field to restrain resizing.
 };
 
+// For SetNextWindowDockFamily() and DockSpace() function
+struct ImGuiDockFamily
+{
+    ImGuiID FamilyId;                   // 0 = unaffiliated
+    bool    CompatibleWithFamilyZero;   // true = can be docked/merged with an unaffiliated window
+
+    ImGuiDockFamily() { FamilyId = 0; CompatibleWithFamilyZero = true; } 
+};
+
 // Data payload for Drag and Drop operations
 struct ImGuiPayload
 {

imgui_internal.h

@@ -541,10 +541,11 @@ struct ImGuiWindowSettings
     ImVec2      ViewportPos;
     ImGuiID     ViewportId;
     ImGuiID     DockId;         // ID of last known DockNode (even if the DockNode is invisible because it has only 1 active window), or 0 if none. 
+    ImGuiID     DockFamilyId;   // ID of dock family if specified
     short       DockOrder;      // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
     bool        Collapsed;
 
-    ImGuiWindowSettings() { Name = NULL; ID = 0; Pos = Size = ViewportPos = ImVec2(0, 0); ViewportId = DockId = 0; DockOrder = -1; Collapsed = false; }
+    ImGuiWindowSettings() { Name = NULL; ID = 0; Pos = Size = ViewportPos = ImVec2(0, 0); ViewportId = DockId = DockFamilyId = 0; DockOrder = -1; Collapsed = false; }
 };
 
 struct ImGuiSettingsHandler
@@ -704,7 +705,7 @@ struct ImGuiNextWindowData
     float                   BgAlphaVal;
     ImGuiID                 ViewportId;
     ImGuiID                 DockId;
-    ImGuiID                 UserTypeId;
+    ImGuiDockFamily         DockFamily;
     ImVec2                  MenuBarOffsetMinVal;                // This is not exposed publicly, so we don't clear it.
 
     ImGuiNextWindowData()
@@ -717,14 +718,14 @@ struct ImGuiNextWindowData
         SizeCallback = NULL;
         SizeCallbackUserData = NULL;
         BgAlphaVal = FLT_MAX;
-        ViewportId = DockId = UserTypeId = 0;
+        ViewportId = DockId = 0;
         MenuBarOffsetMinVal = ImVec2(0.0f, 0.0f);
     }
 
     void    Clear()
     {
         PosCond = SizeCond = ContentSizeCond = CollapsedCond = SizeConstraintCond = FocusCond = BgAlphaCond = ViewportCond = DockCond = 0;
-        UserTypeId = 0;
+        DockFamily = ImGuiDockFamily();
     }
 };
 
@@ -742,7 +743,6 @@ struct ImGuiTabBarSortItem
 struct ImGuiDockNode
 {
     ImGuiID                 ID;
-    ImGuiID                 UserTypeIdFilter;
     ImGuiDockNodeFlags      Flags;
     ImGuiDockNode*          ParentNode;
     ImGuiDockNode*          ChildNodes[2];          // [Split node only] Child nodes (left/right or top/bottom). Consider switching to an array.
@@ -752,6 +752,7 @@ struct ImGuiDockNode
     ImVec2                  Size;                   // Current size
     ImVec2                  SizeRef;                // [Split node only] Last explicitly written-to size (overridden when using a splitter affecting the node), used to calculate Size.
     int                     SplitAxis;              // [Split node only] Split axis (X or Y)
+    ImGuiDockFamily         DockFamily;
 
     ImGuiWindow*            HostWindow;
     ImGuiWindow*            VisibleWindow;
@@ -1208,7 +1209,7 @@ struct IMGUI_API ImGuiWindow
     ImGuiCond               SetWindowDockAllowFlags;            // store acceptable condition flags for SetNextWindowDock() use.
     ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
     ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0,0) when positioning from top-left corner; ImVec2(0.5f,0.5f) for centering; ImVec2(1,1) for bottom right.
-    ImGuiID                 UserTypeId;                         // user value set with SetNextWindowUserType(const char*)
+    ImGuiDockFamily         DockFamily;                         // set with SetNextWindowDockFamily()
 
     ImGuiWindowTempData     DC;                                 // Temporary per-window data, reset at the beginning of the frame. This used to be called ImGuiDrawContext, hence the "DC" variable name.
     ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack