Merge branch 'master' into docking

# Conflicts:
#	imgui.cpp
#	imgui.h
#	imgui_internal.h

docs/CHANGELOG.txt

@@ -102,9 +102,12 @@ Breaking Changes:
 - Renamed ColorEdit/ColorPicker's ImGuiColorEditFlags_RGB/_HSV/_HEX flags to respectively
   ImGuiColorEditFlags_DisplayRGB/_DisplayHSV/_DisplayHex. This is anticipation of adding new
   flags to ColorEdit/ColorPicker functions which would make those ambiguous. (#2384) [@haldean]
+- Renamed GetOverlayDrawList() to GetForegroundDrawList(). Kept redirection function (will obsolete). (#2391)
 
 Other Changes:
 
+- Added GetBackgroundDrawList() helper to quickly get access to a ImDrawList that will be rendered
+  behind every other windows. (#2391)
 - Nav: Fixed a tap on AltGR (e.g. German keyboard) from navigating to the menu layer.
 - DragScalar, InputScalar, SliderScalar: Added support for u8/s8/u16/s16 data types.
   We are reusing function instances for larger types to reduce code size. (#643, #320, #708, #1011)
@@ -130,6 +133,7 @@ Other Changes:
   tree depth instead of a relative one.
 - Log/Capture: Fixed CollapsingHeader trailing ascii representation being "#" instead of "##".
 - Misc: Asserting in NewFrame() if style.WindowMinSize is zero or smaller than (1.0f,1.0f).
+- Demo: Using GetBackgroundDrawList() and GetForegroundDrawList() in "Custom Rendering" demo.
 - Examples: OpenGL: Fix to be able to run on ES 2.0 / WebGL 1.0. [@rmitton, @gabrielcuvillier]
 - Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN
   even if the OpenGL headers/loader happens to define the value. (#2366, #2186)

imgui.cpp

@@ -375,6 +375,7 @@ CODE
  - 2018/XX/XX (1.XX) - Moved IME support functions from io.ImeSetInputScreenPosFn, io.ImeWindowHandle to the PlatformIO api.
  
 
+ - 2019/03/04 (1.69) - renamed GetOverlayDrawList() to GetForegroundDrawList(). Kept redirection function (will obsolete).
  - 2019/02/26 (1.69) - renamed ImGuiColorEditFlags_RGB/ImGuiColorEditFlags_HSV/ImGuiColorEditFlags_HEX to ImGuiColorEditFlags_DisplayRGB/ImGuiColorEditFlags_DisplayHSV/ImGuiColorEditFlags_DisplayHex. Kept redirection enums (will obsolete).
  - 2019/02/14 (1.68) - made it illegal/assert when io.DisplayTime == 0.0f (with an exception for the first frame). If for some reason your time step calculation gives you a zero value, replace it with a dummy small value!
  - 2019/02/01 (1.68) - removed io.DisplayVisibleMin/DisplayVisibleMax (which were marked obsolete and removed from viewport/docking branch already).
@@ -885,7 +886,8 @@ CODE
  A: - You can create a dummy window. Call Begin() with the NoBackground | NoDecoration | NoSavedSettings | NoInputs flags.
       (The ImGuiWindowFlags_NoDecoration flag itself is a shortcut for NoTitleBar | NoResize | NoScrollbar | NoCollapse)
       Then you can retrieve the ImDrawList* via GetWindowDrawList() and draw to it in any way you like.
-    - You can call ImGui::GetOverlayDrawList() and use this draw list to display contents over every other imgui windows (1 overlay per viewport).
+    - You can call ImGui::GetBackgroundDrawList() or ImGui::GetForegroundDrawList() and use those draw list to display 
+      contents behind or over every other imgui windows. (1 bg/fg drawlist per viewport)
     - You can create your own ImDrawList instance. You'll need to initialize them ImGui::GetDrawListSharedData(), or create
       your own ImDrawListSharedData, and then call your rendered code with your own ImDrawList or ImDrawData data.
 
@@ -3133,33 +3135,51 @@ int ImGui::GetFrameCount()
     return GImGui->FrameCount;
 }
 
-ImDrawList* ImGui::GetOverlayDrawList(ImGuiViewport* viewport_public)
+static ImDrawList* GetViewportDrawList(ImGuiViewportP* viewport, size_t drawlist_no, const char* drawlist_name)
 {
-    // Create the draw list on demand, because it is not frequently used for all viewports
+    // Create the draw list on demand, because they are not frequently used for all viewports
     ImGuiContext& g = *GImGui;
-    ImGuiViewportP* viewport = (ImGuiViewportP*)viewport_public;
-    if (viewport->OverlayDrawList == NULL)
+    IM_ASSERT(drawlist_no >= 0 && drawlist_no < IM_ARRAYSIZE(viewport->DrawLists));
+    ImDrawList* draw_list = viewport->DrawLists[drawlist_no];
+    if (draw_list == NULL)
     {
-        viewport->OverlayDrawList = IM_NEW(ImDrawList)(&g.DrawListSharedData);
-        viewport->OverlayDrawList->_OwnerName = "##Overlay";
+        draw_list = IM_NEW(ImDrawList)(&g.DrawListSharedData);
+        draw_list->_OwnerName = drawlist_name;
+        viewport->DrawLists[drawlist_no] = draw_list;
     }
 
     // Our ImDrawList system requires that there is always a command
-    if (viewport->LastFrameOverlayDrawList != g.FrameCount)
+    if (viewport->LastFrameDrawLists[drawlist_no] != g.FrameCount)
     {
-        viewport->OverlayDrawList->Clear();
-        viewport->OverlayDrawList->PushTextureID(g.IO.Fonts->TexID);
-        viewport->OverlayDrawList->PushClipRect(viewport->Pos, viewport->Pos + viewport->Size, false);
-        viewport->OverlayDrawList->Flags = (g.Style.AntiAliasedLines ? ImDrawListFlags_AntiAliasedLines : 0) | (g.Style.AntiAliasedFill ? ImDrawListFlags_AntiAliasedFill : 0);
-        viewport->LastFrameOverlayDrawList = g.FrameCount;
+        draw_list->Clear();
+        draw_list->PushTextureID(g.IO.Fonts->TexID);
+        draw_list->PushClipRect(viewport->Pos, viewport->Pos + viewport->Size, false);
+        draw_list->Flags = (g.Style.AntiAliasedLines ? ImDrawListFlags_AntiAliasedLines : 0) | (g.Style.AntiAliasedFill ? ImDrawListFlags_AntiAliasedFill : 0);
+        viewport->LastFrameDrawLists[drawlist_no] = g.FrameCount;
     }
-    return viewport->OverlayDrawList;
+    return draw_list;
 }
 
-ImDrawList* ImGui::GetOverlayDrawList()
+ImDrawList* ImGui::GetBackgroundDrawList(ImGuiViewport* viewport)
+{
+    return GetViewportDrawList((ImGuiViewportP*)viewport, 0, "##Background");
+}
+
+ImDrawList* ImGui::GetBackgroundDrawList()
+{
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    return GetBackgroundDrawList(window->Viewport);
+}
+
+ImDrawList* ImGui::GetForegroundDrawList(ImGuiViewport* viewport)
+{
+    return GetViewportDrawList((ImGuiViewportP*)viewport, 1, "##Foreground");
+}
+
+ImDrawList* ImGui::GetForegroundDrawList()
 {
     ImGuiWindow* window = GImGui->CurrentWindow;
-    return GetOverlayDrawList(window->Viewport);
+    return GetForegroundDrawList(window->Viewport);
 }
 
 ImDrawListSharedData* ImGui::GetDrawListSharedData()
@@ -3589,7 +3609,6 @@ void ImGui::NewFrame()
     g.DrawListSharedData.ClipRectFullscreen = ImVec4(0.0f, 0.0f, virtual_space_max.x, virtual_space_max.y);
     g.DrawListSharedData.CurveTessellationTol = g.Style.CurveTessellationTol;
 
-    // Setup Overlay draw list for the viewport.
     // Mark rendering data as invalid to prevent user who may have a handle on it to use it.
     for (int n = 0; n < g.Viewports.Size; n++)
     {
@@ -3985,7 +4004,7 @@ static void ImGui::EndFrameDrawDimmedBackgrounds()
                 continue;
             if (g.NavWindowingTargetAnim && viewport == g.NavWindowingTargetAnim->Viewport)
                 continue;
-            ImDrawList* draw_list = GetOverlayDrawList(viewport);
+            ImDrawList* draw_list = GetForegroundDrawList(viewport);
             const ImU32 dim_bg_col = GetColorU32(dim_bg_for_modal ? ImGuiCol_ModalWindowDimBg : ImGuiCol_NavWindowingDimBg, g.DimBgRatio);
             draw_list->AddRectFilled(viewport->Pos, viewport->Pos + viewport->Size, dim_bg_col);
         }
@@ -4131,7 +4150,13 @@ void ImGui::Render()
     // Gather ImDrawList to render (for each active window)
     g.IO.MetricsRenderVertices = g.IO.MetricsRenderIndices = g.IO.MetricsRenderWindows = 0;
     for (int n = 0; n != g.Viewports.Size; n++)
-        g.Viewports[n]->DrawDataBuilder.Clear();
+    {
+        ImGuiViewportP* viewport = g.Viewports[n];
+        viewport->DrawDataBuilder.Clear();
+        if (viewport->DrawLists[0] != NULL)
+            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], GetBackgroundDrawList(viewport));
+    }
+
     ImGuiWindow* windows_to_render_front_most[2];
     windows_to_render_front_most[0] = (g.NavWindowingTarget && !(g.NavWindowingTarget->Flags & ImGuiWindowFlags_NoBringToFrontOnFocus)) ? g.NavWindowingTarget->RootWindow : NULL;
     windows_to_render_front_most[1] = g.NavWindowingTarget ? g.NavWindowingList : NULL;
@@ -4155,8 +4180,8 @@ void ImGui::Render()
     {
         ImGuiViewportP* viewport = g.Viewports[n];
         viewport->DrawDataBuilder.FlattenIntoSingleLayer();
-        if (viewport->OverlayDrawList != NULL)
-            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], GetOverlayDrawList(viewport));
+        if (viewport->DrawLists[1] != NULL)
+            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], GetForegroundDrawList(viewport));
         SetupViewportDrawData(viewport, &viewport->DrawDataBuilder.Layers[0]);
         g.IO.MetricsRenderVertices += viewport->DrawData->TotalVtxCount;
         g.IO.MetricsRenderIndices += viewport->DrawData->TotalIdxCount;
@@ -5055,7 +5080,7 @@ static void ImGui::UpdateManualResize(ImGuiWindow* window, const ImVec2& size_au
         if (resize_rect.Min.y > resize_rect.Max.y) ImSwap(resize_rect.Min.y, resize_rect.Max.y);
         bool hovered, held;
         ButtonBehavior(resize_rect, window->GetID((void*)(intptr_t)resize_grip_n), &hovered, &held, ImGuiButtonFlags_FlattenChildren | ImGuiButtonFlags_NoNavFocus);
-        //GetOverlayDrawList(window)->AddRect(resize_rect.Min, resize_rect.Max, IM_COL32(255, 255, 0, 255));
+        //GetForegroundDrawList(window)->AddRect(resize_rect.Min, resize_rect.Max, IM_COL32(255, 255, 0, 255));
         if (hovered || held)
             g.MouseCursor = (resize_grip_n & 1) ? ImGuiMouseCursor_ResizeNESW : ImGuiMouseCursor_ResizeNWSE;
 
@@ -5080,7 +5105,7 @@ static void ImGui::UpdateManualResize(ImGuiWindow* window, const ImVec2& size_au
         bool hovered, held;
         ImRect border_rect = GetResizeBorderRect(window, border_n, grip_hover_inner_size, WINDOWS_RESIZE_FROM_EDGES_HALF_THICKNESS);
         ButtonBehavior(border_rect, window->GetID((void*)(intptr_t)(border_n + 4)), &hovered, &held, ImGuiButtonFlags_FlattenChildren);
-        //GetOverlayDrawList(window)->AddRect(border_rect.Min, border_rect.Max, IM_COL32(255, 255, 0, 255));
+        //GetForegroundDrawLists(window)->AddRect(border_rect.Min, border_rect.Max, IM_COL32(255, 255, 0, 255));
         if ((hovered && g.HoveredIdTimer > WINDOWS_RESIZE_FROM_EDGES_FEEDBACK_TIMER) || held)
         {
             g.MouseCursor = (border_n & 1) ? ImGuiMouseCursor_ResizeEW : ImGuiMouseCursor_ResizeNS;
@@ -7620,8 +7645,8 @@ bool ImGui::BeginPopupContextVoid(const char* str_id, int mouse_button)
 ImVec2 ImGui::FindBestWindowPosForPopupEx(const ImVec2& ref_pos, const ImVec2& size, ImGuiDir* last_dir, const ImRect& r_outer, const ImRect& r_avoid, ImGuiPopupPositionPolicy policy)
 {
     ImVec2 base_pos_clamped = ImClamp(ref_pos, r_outer.Min, r_outer.Max - size);
-    //GImGui->OverlayDrawList.AddRect(r_avoid.Min, r_avoid.Max, IM_COL32(255,0,0,255));
-    //GImGui->OverlayDrawList.AddRect(r_outer.Min, r_outer.Max, IM_COL32(0,255,0,255));
+    //GetForegroundDrawList()->AddRect(r_avoid.Min, r_avoid.Max, IM_COL32(255,0,0,255));
+    //GetForegroundDrawList()->AddRect(r_outer.Min, r_outer.Max, IM_COL32(0,255,0,255));
 
     // Combo Box policy (we want a connecting edge)
     if (policy == ImGuiPopupPositionPolicy_ComboBox)
@@ -8544,7 +8569,7 @@ static bool NavScoreItem(ImGuiNavMoveResult* result, ImRect cand)
     if (ImGui::IsMouseHoveringRect(cand.Min, cand.Max))
     {
         ImFormatString(buf, IM_ARRAYSIZE(buf), "dbox (%.2f,%.2f->%.4f)\ndcen (%.2f,%.2f->%.4f)\nd (%.2f,%.2f->%.4f)\nnav %c, quadrant %c", dbx, dby, dist_box, dcx, dcy, dist_center, dax, day, dist_axial, "WENS"[g.NavMoveDir], "WENS"[quadrant]);
-        ImDrawList* draw_list = ImGui::GetOverlayDrawList(window);
+        ImDrawList* draw_list = ImGui::GetForegroundDrawList(window);
         draw_list->AddRect(curr.Min, curr.Max, IM_COL32(255,200,0,100));
         draw_list->AddRect(cand.Min, cand.Max, IM_COL32(255,255,0,200));
         draw_list->AddRectFilled(cand.Max-ImVec2(4,4), cand.Max+ImGui::CalcTextSize(buf)+ImVec2(4,4), IM_COL32(40,0,0,150));
@@ -8556,7 +8581,7 @@ static bool NavScoreItem(ImGuiNavMoveResult* result, ImRect cand)
         if (quadrant == g.NavMoveDir)
         {
             ImFormatString(buf, IM_ARRAYSIZE(buf), "%.0f/%.0f", dist_box, dist_center);
-            ImDrawList* draw_list = ImGui::GetOverlayDrawList(window);
+            ImDrawList* draw_list = ImGui::GetForegroundDrawList(window);
             draw_list->AddRectFilled(cand.Min, cand.Max, IM_COL32(255, 0, 0, 200));
             draw_list->AddText(g.IO.FontDefault, 13.0f, cand.Min, IM_COL32(255, 255, 255, 255), buf);
         }
@@ -8862,7 +8887,7 @@ ImVec2 ImGui::GetNavInputAmount2d(ImGuiNavDirSourceFlags dir_sources, ImGuiInput
 static void NavScrollToBringItemIntoView(ImGuiWindow* window, const ImRect& item_rect)
 {
     ImRect window_rect(window->InnerMainRect.Min - ImVec2(1, 1), window->InnerMainRect.Max + ImVec2(1, 1));
-    //GetOverlayDrawList(window)->AddRect(window_rect.Min, window_rect.Max, IM_COL32_WHITE); // [DEBUG]
+    //GetForegroundDrawList(window)->AddRect(window_rect.Min, window_rect.Max, IM_COL32_WHITE); // [DEBUG]
     if (window_rect.Contains(item_rect))
         return;
 
@@ -9152,11 +9177,15 @@ static void ImGui::NavUpdate()
     g.NavScoringRectScreen.Min.x = ImMin(g.NavScoringRectScreen.Min.x + 1.0f, g.NavScoringRectScreen.Max.x);
     g.NavScoringRectScreen.Max.x = g.NavScoringRectScreen.Min.x;
     IM_ASSERT(!g.NavScoringRectScreen.IsInverted()); // Ensure if we have a finite, non-inverted bounding box here will allows us to remove extraneous ImFabs() calls in NavScoreItem().
-    //g.OverlayDrawList.AddRect(g.NavScoringRectScreen.Min, g.NavScoringRectScreen.Max, IM_COL32(255,200,0,255)); // [DEBUG]
+    //GetForegroundDrawList()->AddRect(g.NavScoringRectScreen.Min, g.NavScoringRectScreen.Max, IM_COL32(255,200,0,255)); // [DEBUG]
     g.NavScoringCount = 0;
 #if IMGUI_DEBUG_NAV_RECTS
-    if (g.NavWindow) { for (int layer = 0; layer < 2; layer++) GetOverlayDrawList(g.NavWindow)->AddRect(g.NavWindow->Pos + g.NavWindow->NavRectRel[layer].Min, g.NavWindow->Pos + g.NavWindow->NavRectRel[layer].Max, IM_COL32(255,200,0,255)); } // [DEBUG]
-    if (g.NavWindow) { ImU32 col = (!g.NavWindow->Hidden) ? IM_COL32(255,0,255,255) : IM_COL32(255,0,0,255); ImVec2 p = NavCalcPreferredRefPos(); char buf[32]; ImFormatString(buf, 32, "%d", g.NavLayer); GetOverlayDrawList(g.NavWindow)->AddCircleFilled(p, 3.0f, col); GetOverlayDrawList(g.NavWindow)->AddText(NULL, 13.0f, p + ImVec2(8,-4), col, buf); }
+    if (g.NavWindow)
+    {
+        ImDrawList* draw_list = GetForegroundDrawList(g.NavWindow);
+        if (1) { for (int layer = 0; layer < 2; layer++) draw_list->AddRect(g.NavWindow->Pos + g.NavWindow->NavRectRel[layer].Min, g.NavWindow->Pos + g.NavWindow->NavRectRel[layer].Max, IM_COL32(255, 200, 0, 255)); } // [DEBUG] 
+        if (1) { ImU32 col = (!g.NavWindow->Hidden) ? IM_COL32(255, 0, 255, 255) : IM_COL32(255, 0, 0, 255); ImVec2 p = NavCalcPreferredRefPos(); char buf[32]; ImFormatString(buf, 32, "%d", g.NavLayer); draw_list->AddCircleFilled(p, 3.0f, col); draw_list->AddText(NULL, 13.0f, p + ImVec2(8, -4), col, buf); }
+    }
 #endif
 }
 
@@ -12309,9 +12338,9 @@ static void ImGui::DockNodePreviewDockRender(ImGuiWindow* host_window, ImGuiDock
     // In case the two windows involved are on different viewports, we will draw the overlay on each of them.
     int overlay_draw_lists_count = 0;
     ImDrawList* overlay_draw_lists[2];
-    overlay_draw_lists[overlay_draw_lists_count++] = GetOverlayDrawList(host_window->Viewport);
+    overlay_draw_lists[overlay_draw_lists_count++] = GetForegroundDrawList(host_window->Viewport);
     if (host_window->Viewport != root_payload->Viewport && !is_transparent_payload)
-        overlay_draw_lists[overlay_draw_lists_count++] = GetOverlayDrawList(root_payload->Viewport);
+        overlay_draw_lists[overlay_draw_lists_count++] = GetForegroundDrawList(root_payload->Viewport);
 
     // Draw main preview rectangle
     const ImU32 overlay_col_tabs = GetColorU32(ImGuiCol_TabActive);
@@ -12586,7 +12615,7 @@ void ImGui::DockNodeTreeUpdateSplitter(ImGuiDockNode* node)
         bb.Max = child_1->Pos;
         bb.Min[axis] += child_0->Size[axis];
         bb.Max[axis ^ 1] += child_1->Size[axis ^ 1];
-        //if (g.IO.KeyCtrl) GetOverlayDrawList(g.CurrentWindow->Viewport)->AddRect(bb.Min, bb.Max, IM_COL32(255,0,255,255));
+        //if (g.IO.KeyCtrl) GetForegroundDrawList(g.CurrentWindow->Viewport)->AddRect(bb.Min, bb.Max, IM_COL32(255,0,255,255));
 
         if (node->Flags & ImGuiDockNodeFlags_NoResize)
         {
@@ -13830,9 +13859,9 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                 return;
             }
 
-            ImDrawList* overlay_draw_list = viewport ? GetOverlayDrawList(viewport) : NULL; // Render additional visuals into the top-most draw list
-            if (window && overlay_draw_list && ImGui::IsItemHovered())
-                overlay_draw_list->AddRect(window->Pos, window->Pos + window->Size, IM_COL32(255, 255, 0, 255));
+            ImDrawList* fg_draw_list = viewport ? GetForegroundDrawList(viewport) : NULL; // Render additional visuals into the top-most draw list
+            if (window && fg_draw_list && ImGui::IsItemHovered())
+                fg_draw_list->AddRect(window->Pos, window->Pos + window->Size, IM_COL32(255, 255, 0, 255));
             if (!node_open)
                 return;
 
@@ -13848,14 +13877,14 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                 }
                 ImDrawIdx* idx_buffer = (draw_list->IdxBuffer.Size > 0) ? draw_list->IdxBuffer.Data : NULL;
                 bool pcmd_node_open = ImGui::TreeNode((void*)(pcmd - draw_list->CmdBuffer.begin()), "Draw %4d %s vtx, tex 0x%p, clip_rect (%4.0f,%4.0f)-(%4.0f,%4.0f)", pcmd->ElemCount, draw_list->IdxBuffer.Size > 0 ? "indexed" : "non-indexed", pcmd->TextureId, pcmd->ClipRect.x, pcmd->ClipRect.y, pcmd->ClipRect.z, pcmd->ClipRect.w);
-                if (show_draw_cmd_clip_rects && overlay_draw_list && ImGui::IsItemHovered())
+                if (show_draw_cmd_clip_rects && fg_draw_list && ImGui::IsItemHovered())
                 {
                     ImRect clip_rect = pcmd->ClipRect;
                     ImRect vtxs_rect;
                     for (int i = elem_offset; i < elem_offset + (int)pcmd->ElemCount; i++)
                         vtxs_rect.Add(draw_list->VtxBuffer[idx_buffer ? idx_buffer[i] : i].pos);
-                    clip_rect.Floor(); overlay_draw_list->AddRect(clip_rect.Min, clip_rect.Max, IM_COL32(255,255,0,255));
-                    vtxs_rect.Floor(); overlay_draw_list->AddRect(vtxs_rect.Min, vtxs_rect.Max, IM_COL32(255,0,255,255));
+                    clip_rect.Floor(); fg_draw_list->AddRect(clip_rect.Min, clip_rect.Max, IM_COL32(255,255,0,255));
+                    vtxs_rect.Floor(); fg_draw_list->AddRect(vtxs_rect.Min, vtxs_rect.Max, IM_COL32(255,0,255,255));
                 }
                 if (!pcmd_node_open)
                     continue;
@@ -13877,12 +13906,12 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                                 (n == 0) ? "idx" : "   ", idx_i, v.pos.x, v.pos.y, v.uv.x, v.uv.y, v.col);
                         }
                         ImGui::Selectable(buf, false);
-                        if (overlay_draw_list && ImGui::IsItemHovered())
+                        if (fg_draw_list && ImGui::IsItemHovered())
                         {
-                            ImDrawListFlags backup_flags = overlay_draw_list->Flags;
-                            overlay_draw_list->Flags &= ~ImDrawListFlags_AntiAliasedLines; // Disable AA on triangle outlines at is more readable for very large and thin triangles.
-                            overlay_draw_list->AddPolyline(triangles_pos, 3, IM_COL32(255,255,0,255), true, 1.0f);
-                            overlay_draw_list->Flags = backup_flags;
+                            ImDrawListFlags backup_flags = fg_draw_list->Flags;
+                            fg_draw_list->Flags &= ~ImDrawListFlags_AntiAliasedLines; // Disable AA on triangle outlines at is more readable for very large and thin triangles.
+                            fg_draw_list->AddPolyline(triangles_pos, 3, IM_COL32(255,255,0,255), true, 1.0f);
+                            fg_draw_list->Flags = backup_flags;
                         }
                     }
                 ImGui::TreePop();
@@ -14033,11 +14062,10 @@ void ImGui::ShowMetricsWindow(bool* p_open)
             ImGuiWindow* window = g.Windows[n];
             if (!window->WasActive || ((window->Flags & ImGuiWindowFlags_ChildWindow) && window->DockNode == NULL))
                 continue;
-
             char buf[64] = "";
             char* p = buf;
             p += ImFormatString(p, buf + IM_ARRAYSIZE(buf) - p, "Order: %d\n", window->BeginOrderWithinContext);
-            ImDrawList* overlay_draw_list = GetOverlayDrawList(window->Viewport);
+            ImDrawList* overlay_draw_list = GetForegroundDrawList(window->Viewport);
             overlay_draw_list->AddRectFilled(window->Pos - ImVec2(1, 1), window->Pos + CalcTextSize(buf) + ImVec2(1, 1), IM_COL32(200, 100, 100, 255));
             overlay_draw_list->AddText(NULL, 0.0f, window->Pos, IM_COL32(255, 255, 255, 255), buf);
         }
@@ -14177,7 +14205,7 @@ void ImGui::ShowDockingDebug()
                         continue;
                 char buf[64] = "";
                 char* p = buf;
-                ImDrawList* overlay_draw_list = node->HostWindow ? GetOverlayDrawList(node->HostWindow) : GetOverlayDrawList((ImGuiViewportP*)GetMainViewport());
+                ImDrawList* overlay_draw_list = node->HostWindow ? GetForegroundDrawList(node->HostWindow) : GetForegroundDrawList((ImGuiViewportP*)GetMainViewport());
                 p += ImFormatString(p, buf + IM_ARRAYSIZE(buf) - p, "DockId: %X%s\n", node->ID, node->IsCentralNode ? " *CentralNode*" : "");
                 p += ImFormatString(p, buf + IM_ARRAYSIZE(buf) - p, "Size: (%.0f, %.0f)\n", node->Size.x, node->Size.y);
                 p += ImFormatString(p, buf + IM_ARRAYSIZE(buf) - p, "SizeRef: (%.0f, %.0f)\n", node->SizeRef.x, node->SizeRef.y);

imgui.h

@@ -652,9 +652,11 @@ namespace ImGui
     IMGUI_API bool          IsRectVisible(const ImVec2& rect_min, const ImVec2& rect_max);      // test if rectangle (in screen space) is visible / not clipped. to perform coarse clipping on user's side.
     IMGUI_API double        GetTime();                                                          // get global imgui time. incremented by io.DeltaTime every frame.
     IMGUI_API int           GetFrameCount();                                                    // get global imgui frame count. incremented by 1 every frame.
-    IMGUI_API ImDrawList*   GetOverlayDrawList();                                               // get overlay draw list for the viewport associated to the current window. this draw list will be the last rendered. useful to quickly draw overlays shapes/text.
-    IMGUI_API ImDrawList*   GetOverlayDrawList(ImGuiViewport* viewport);                        // get overlay draw list for the given viewport. 
-    IMGUI_API ImDrawListSharedData* GetDrawListSharedData();                                    // you may use this when creating your own ImDrawList instances
+    IMGUI_API ImDrawList*   GetBackgroundDrawList();                                            // get background draw list for the viewport associated to the current window. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
+    IMGUI_API ImDrawList*   GetForegroundDrawList();                                            // get foreground draw list for the viewport associated to the current window. this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    IMGUI_API ImDrawList*   GetBackgroundDrawList(ImGuiViewport* viewport);                     // get background draw list for the given viewport. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
+    IMGUI_API ImDrawList*   GetForegroundDrawList(ImGuiViewport* viewport);                     // get foreground draw list for the given viewport. this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    IMGUI_API ImDrawListSharedData* GetDrawListSharedData();                                    // you may use this when creating your own ImDrawList instances.
     IMGUI_API const char*   GetStyleColorName(ImGuiCol idx);                                    // get a string corresponding to the enum value (for display, saving, etc.).
     IMGUI_API void          SetStateStorage(ImGuiStorage* storage);                             // replace current window storage with our own (if you want to manipulate it yourself, typically clear subsection of it)
     IMGUI_API ImGuiStorage* GetStateStorage();
@@ -1589,6 +1591,8 @@ struct ImGuiWindowClass
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
 namespace ImGui
 {
+    // OBSOLETED in 1.69 (from Mar 2019)
+    static inline ImDrawList* GetOverlayDrawList()            { return GetForegroundDrawList(); }
     // OBSOLETED in 1.66 (from Sep 2018)
     static inline void  SetScrollHere(float center_ratio=0.5f){ SetScrollHereY(center_ratio); }
     // OBSOLETED in 1.63 (between Aug 2018 and Sept 2018)

imgui_demo.cpp

@@ -4059,15 +4059,17 @@ static void ShowExampleAppCustomRendering(bool* p_open)
     // In this example we are not using the maths operators!
     ImDrawList* draw_list = ImGui::GetWindowDrawList();
 
+    if (ImGui::BeginTabBar("##TabBar"))
+    {
         // Primitives
-    ImGui::Text("Primitives");
+        if (ImGui::BeginTabItem("Primitives"))
+        {
             static float sz = 36.0f;
             static float thickness = 4.0f;
             static ImVec4 col = ImVec4(1.0f, 1.0f, 0.4f, 1.0f);
             ImGui::DragFloat("Size", &sz, 0.2f, 2.0f, 72.0f, "%.0f");
             ImGui::DragFloat("Thickness", &thickness, 0.05f, 1.0f, 8.0f, "%.02f");
             ImGui::ColorEdit4("Color", &col.x);
-    {
             const ImVec2 p = ImGui::GetCursorScreenPos();
             const ImU32 col32 = ImColor(col);
             float x = p.x + 4.0f, y = p.y + 4.0f, spacing = 8.0f;
@@ -4075,36 +4077,37 @@ static void ShowExampleAppCustomRendering(bool* p_open)
             {
                 // First line uses a thickness of 1.0, second line uses the configurable thickness
                 float th = (n == 0) ? 1.0f : thickness;
-            draw_list->AddCircle(ImVec2(x+sz*0.5f, y+sz*0.5f), sz*0.5f, col32, 6, th); x += sz+spacing;     // Hexagon
-            draw_list->AddCircle(ImVec2(x+sz*0.5f, y+sz*0.5f), sz*0.5f, col32, 20, th); x += sz+spacing;    // Circle
-            draw_list->AddRect(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, 0.0f,  ImDrawCornerFlags_All, th); x += sz+spacing;
-            draw_list->AddRect(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, 10.0f, ImDrawCornerFlags_All, th); x += sz+spacing;
-            draw_list->AddRect(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, 10.0f, ImDrawCornerFlags_TopLeft|ImDrawCornerFlags_BotRight, th); x += sz+spacing;
-            draw_list->AddTriangle(ImVec2(x+sz*0.5f, y), ImVec2(x+sz,y+sz-0.5f), ImVec2(x,y+sz-0.5f), col32, th); x += sz+spacing;
-            draw_list->AddLine(ImVec2(x, y), ImVec2(x+sz, y   ), col32, th); x += sz+spacing;               // Horizontal line (note: drawing a filled rectangle will be faster!)
-            draw_list->AddLine(ImVec2(x, y), ImVec2(x,    y+sz), col32, th); x += spacing;                  // Vertical line (note: drawing a filled rectangle will be faster!)
-            draw_list->AddLine(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, th); x += sz+spacing;               // Diagonal line
-            draw_list->AddBezierCurve(ImVec2(x, y), ImVec2(x+sz*1.3f,y+sz*0.3f), ImVec2(x+sz-sz*1.3f,y+sz-sz*0.3f), ImVec2(x+sz, y+sz), col32, th);
+                draw_list->AddCircle(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col32, 6, th); x += sz + spacing;     // Hexagon
+                draw_list->AddCircle(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col32, 20, th); x += sz + spacing;    // Circle
+                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, 0.0f, ImDrawCornerFlags_All, th); x += sz + spacing;
+                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, 10.0f, ImDrawCornerFlags_All, th); x += sz + spacing;
+                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, 10.0f, ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_BotRight, th); x += sz + spacing;
+                draw_list->AddTriangle(ImVec2(x + sz*0.5f, y), ImVec2(x + sz, y + sz - 0.5f), ImVec2(x, y + sz - 0.5f), col32, th); x += sz + spacing;
+                draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y), col32, th); x += sz + spacing;               // Horizontal line (note: drawing a filled rectangle will be faster!)
+                draw_list->AddLine(ImVec2(x, y), ImVec2(x, y + sz), col32, th); x += spacing;                  // Vertical line (note: drawing a filled rectangle will be faster!)
+                draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, th); x += sz + spacing;               // Diagonal line
+                draw_list->AddBezierCurve(ImVec2(x, y), ImVec2(x + sz*1.3f, y + sz*0.3f), ImVec2(x + sz - sz*1.3f, y + sz - sz*0.3f), ImVec2(x + sz, y + sz), col32, th);
                 x = p.x + 4;
-            y += sz+spacing;
-        }
-        draw_list->AddCircleFilled(ImVec2(x+sz*0.5f, y+sz*0.5f), sz*0.5f, col32, 6); x += sz+spacing;       // Hexagon
-        draw_list->AddCircleFilled(ImVec2(x+sz*0.5f, y+sz*0.5f), sz*0.5f, col32, 32); x += sz+spacing;      // Circle
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+sz, y+sz), col32); x += sz+spacing;
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, 10.0f); x += sz+spacing;
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+sz, y+sz), col32, 10.0f, ImDrawCornerFlags_TopLeft|ImDrawCornerFlags_BotRight); x += sz+spacing;
-        draw_list->AddTriangleFilled(ImVec2(x+sz*0.5f, y), ImVec2(x+sz,y+sz-0.5f), ImVec2(x,y+sz-0.5f), col32); x += sz+spacing;
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+sz, y+thickness), col32); x += sz+spacing;          // Horizontal line (faster than AddLine, but only handle integer thickness)
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+thickness, y+sz), col32); x += spacing+spacing;     // Vertical line (faster than AddLine, but only handle integer thickness)
-        draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x+1, y+1), col32);          x += sz;                  // Pixel (faster than AddLine)
-        draw_list->AddRectFilledMultiColor(ImVec2(x, y), ImVec2(x+sz, y+sz), IM_COL32(0,0,0,255), IM_COL32(255,0,0,255), IM_COL32(255,255,0,255), IM_COL32(0,255,0,255));
-        ImGui::Dummy(ImVec2((sz+spacing)*8, (sz+spacing)*3));
+                y += sz + spacing;
+            }
+            draw_list->AddCircleFilled(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col32, 6); x += sz + spacing;       // Hexagon
+            draw_list->AddCircleFilled(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col32, 32); x += sz + spacing;      // Circle
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col32); x += sz + spacing;
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, 10.0f); x += sz + spacing;
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + sz), col32, 10.0f, ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_BotRight); x += sz + spacing;
+            draw_list->AddTriangleFilled(ImVec2(x + sz*0.5f, y), ImVec2(x + sz, y + sz - 0.5f), ImVec2(x, y + sz - 0.5f), col32); x += sz + spacing;
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + sz, y + thickness), col32); x += sz + spacing;          // Horizontal line (faster than AddLine, but only handle integer thickness)
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + thickness, y + sz), col32); x += spacing + spacing;     // Vertical line (faster than AddLine, but only handle integer thickness)
+            draw_list->AddRectFilled(ImVec2(x, y), ImVec2(x + 1, y + 1), col32);          x += sz;                  // Pixel (faster than AddLine)
+            draw_list->AddRectFilledMultiColor(ImVec2(x, y), ImVec2(x + sz, y + sz), IM_COL32(0, 0, 0, 255), IM_COL32(255, 0, 0, 255), IM_COL32(255, 255, 0, 255), IM_COL32(0, 255, 0, 255));
+            ImGui::Dummy(ImVec2((sz + spacing) * 8, (sz + spacing) * 3));
+            ImGui::EndTabItem();
         }
-    ImGui::Separator();
+
+        if (ImGui::BeginTabItem("Canvas"))
         {
             static ImVector<ImVec2> points;
             static bool adding_line = false;
-        ImGui::Text("Canvas example");
             if (ImGui::Button("Clear")) points.clear();
             if (points.Size >= 2) { ImGui::SameLine(); if (ImGui::Button("Undo")) { points.pop_back(); points.pop_back(); } }
             ImGui::Text("Left-click and drag to add lines,\nRight-click to undo");
@@ -4149,7 +4152,28 @@ static void ShowExampleAppCustomRendering(bool* p_open)
             draw_list->PopClipRect();
             if (adding_preview)
                 points.pop_back();
+            ImGui::EndTabItem();
         }
+
+        if (ImGui::BeginTabItem("BG/FG draw lists"))
+        {
+            static bool draw_bg = true;
+            static bool draw_fg = true;
+            ImGui::Checkbox("Draw in Background draw list", &draw_bg);
+            ImGui::Checkbox("Draw in Foreground draw list", &draw_fg);
+            ImVec2 window_pos = ImGui::GetWindowPos();
+            ImVec2 window_size = ImGui::GetWindowSize();
+            ImVec2 window_center = ImVec2(window_pos.x + window_size.x * 0.5f, window_pos.y + window_size.y * 0.5f);
+            if (draw_bg)
+                ImGui::GetBackgroundDrawList()->AddCircle(window_center, window_size.x * 0.6f, IM_COL32(255, 0, 0, 200), 32, 10);
+            if (draw_fg)
+                ImGui::GetForegroundDrawList()->AddCircle(window_center, window_size.y * 0.6f, IM_COL32(0, 255, 0, 200), 32, 10);
+            ImGui::EndTabItem();
+        }
+
+        ImGui::EndTabBar();
+    }
+
     ImGui::End();
 }
 

imgui_draw.cpp

@@ -2976,7 +2976,7 @@ void ImGui::RenderMouseCursor(ImVec2 pos, float scale, ImGuiMouseCursor mouse_cu
             if (!viewport->GetRect().Overlaps(ImRect(pos, pos + ImVec2(size.x + 2, size.y + 2) * scale)))
                 continue;
 
-            ImDrawList* draw_list = GetOverlayDrawList(viewport);
+            ImDrawList* draw_list = GetForegroundDrawList(viewport);
             draw_list->PushTextureID(tex_id);
             draw_list->AddImage(tex_id, pos + ImVec2(1,0)*scale, pos + ImVec2(1,0)*scale + size*scale, uv[2], uv[3], col_shadow);
             draw_list->AddImage(tex_id, pos + ImVec2(2,0)*scale, pos + ImVec2(2,0)*scale + size*scale, uv[2], uv[3], col_shadow);

imgui_internal.h

@@ -737,7 +737,7 @@ struct ImGuiViewportP : public ImGuiViewport
 {
     int                 Idx;
     int                 LastFrameActive;          // Last frame number this viewport was activated by a window
-    int                 LastFrameOverlayDrawList;
+    int                 LastFrameDrawLists[2];    // Last frame number the background (0) and foreground (1) draw lists were used
     int                 LastFrontMostStampCount;  // Last stamp number from when a window hosted by this viewport was made front-most (by comparing this value between two viewport we have an implicit viewport z-order
     ImGuiID             LastNameHash;
     ImVec2              LastPos;
@@ -747,15 +747,15 @@ struct ImGuiViewportP : public ImGuiViewport
     bool                PlatformWindowCreated;
     bool                PlatformWindowMinimized;  // When minimized we tend to avoid using the viewport pos/size for clipping window or testing if they are contained in the viewport
     ImGuiWindow*        Window;                   // Set when the viewport is owned by a window (and ImGuiViewportFlags_CanHostOtherWindows is NOT set)
-    ImDrawList*         OverlayDrawList;          // For convenience, a draw list we can render to that's always rendered last (we use it to draw software mouse cursor when io.MouseDrawCursor is set)
+    ImDrawList*         DrawLists[2];             // Convenience background (0) and foreground (1) draw lists. We use them to draw software mouser cursor when io.MouseDrawCursor is set and to draw most debug overlays.
     ImDrawData          DrawDataP;
     ImDrawDataBuilder   DrawDataBuilder;
     ImVec2              LastPlatformPos;
     ImVec2              LastPlatformSize;
     ImVec2              LastRendererSize;
 
-    ImGuiViewportP()            { Idx = -1; LastFrameActive = LastFrameOverlayDrawList = LastFrontMostStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; PlatformMonitor = -1; PlatformWindowCreated = PlatformWindowMinimized = false; Window = NULL; OverlayDrawList = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
-    ~ImGuiViewportP()           { if (OverlayDrawList) IM_DELETE(OverlayDrawList); }
+    ImGuiViewportP()            { Idx = -1; LastFrameActive = LastFrameDrawLists[0] = LastFrameDrawLists[1] = LastFrontMostStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; PlatformMonitor = -1; PlatformWindowCreated = PlatformWindowMinimized = false; Window = NULL; DrawLists[0] = DrawLists[1] = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
+    ~ImGuiViewportP()           { if (DrawLists[0]) IM_DELETE(DrawLists[0]); if (DrawLists[1]) IM_DELETE(DrawLists[1]); }
     ImRect  GetRect() const     { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
     ImVec2  GetCenter() const   { return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
     void    ClearRequestFlags() { PlatformRequestClose = PlatformRequestMove = PlatformRequestResize = false; }
@@ -1547,7 +1547,7 @@ namespace ImGui
 
     IMGUI_API void          SetCurrentFont(ImFont* font);
     inline ImFont*          GetDefaultFont() { ImGuiContext& g = *GImGui; return g.IO.FontDefault ? g.IO.FontDefault : g.IO.Fonts->Fonts[0]; }
-    inline ImDrawList*      GetOverlayDrawList(ImGuiWindow* window) { return GetOverlayDrawList(window->Viewport); }
+    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { return GetForegroundDrawList(window->Viewport); }
 
     // Init
     IMGUI_API void          Initialize(ImGuiContext* context);

imgui_widgets.cpp

@@ -6755,7 +6755,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     {
         // Enlarge tab display when hovering
         bb.Max.x = bb.Min.x + (float)(int)ImLerp(bb.GetWidth(), tab->WidthContents, ImSaturate((g.HoveredIdNotActiveTimer - 0.40f) * 6.0f));
-        display_draw_list = GetOverlayDrawList(window);
+        display_draw_list = GetForegroundDrawList(window);
         TabItemBackground(display_draw_list, bb, flags, GetColorU32(ImGuiCol_TitleBgActive));
     }
 #endif