Updated ImGui.

3rdparty/dear-imgui/imgui.cpp

@@ -3504,16 +3504,21 @@ void ImGui::NewFrame()
     IM_ASSERT(g.Font->IsLoaded());
     g.DrawListSharedData.ClipRectFullscreen = ImVec4(0.0f, 0.0f, g.IO.DisplaySize.x, g.IO.DisplaySize.y);
     g.DrawListSharedData.CurveTessellationTol = g.Style.CurveTessellationTol;
+    g.DrawListSharedData.InitialFlags = ImDrawListFlags_None;
+    if (g.Style.AntiAliasedLines)
+        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLines;
+    if (g.Style.AntiAliasedFill)
+        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedFill;
+    if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)
+        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AllowVtxOffset;
 
     g.BackgroundDrawList.Clear();
     g.BackgroundDrawList.PushTextureID(g.IO.Fonts->TexID);
     g.BackgroundDrawList.PushClipRectFullScreen();
-    g.BackgroundDrawList.Flags = (g.Style.AntiAliasedLines ? ImDrawListFlags_AntiAliasedLines : 0) | (g.Style.AntiAliasedFill ? ImDrawListFlags_AntiAliasedFill : 0);
 
     g.ForegroundDrawList.Clear();
     g.ForegroundDrawList.PushTextureID(g.IO.Fonts->TexID);
     g.ForegroundDrawList.PushClipRectFullScreen();
-    g.ForegroundDrawList.Flags = (g.Style.AntiAliasedLines ? ImDrawListFlags_AntiAliasedLines : 0) | (g.Style.AntiAliasedFill ? ImDrawListFlags_AntiAliasedFill : 0);
 
     // Mark rendering data as invalid to prevent user who may have a handle on it to use it.
     g.DrawData.Clear();
@@ -3777,19 +3782,28 @@ static void AddDrawListToDrawData(ImVector<ImDrawList*>* out_list, ImDrawList* d
             return;
     }
 
-    // Draw list sanity check. Detect mismatch between PrimReserve() calls and incrementing _VtxCurrentIdx, _VtxWritePtr etc. May trigger for you if you are using PrimXXX functions incorrectly.
+    // Draw list sanity check. Detect mismatch between PrimReserve() calls and incrementing _VtxCurrentIdx, _VtxWritePtr etc. 
+    // May trigger for you if you are using PrimXXX functions incorrectly.
     IM_ASSERT(draw_list->VtxBuffer.Size == 0 || draw_list->_VtxWritePtr == draw_list->VtxBuffer.Data + draw_list->VtxBuffer.Size);
     IM_ASSERT(draw_list->IdxBuffer.Size == 0 || draw_list->_IdxWritePtr == draw_list->IdxBuffer.Data + draw_list->IdxBuffer.Size);
-    IM_ASSERT((int)draw_list->_VtxCurrentIdx == draw_list->VtxBuffer.Size);
+    if (!(draw_list->Flags & ImDrawListFlags_AllowVtxOffset))
+        IM_ASSERT((int)draw_list->_VtxCurrentIdx == draw_list->VtxBuffer.Size);
 
     // Check that draw_list doesn't use more vertices than indexable (default ImDrawIdx = unsigned short = 2 bytes = 64K vertices per ImDrawList = per window)
     // If this assert triggers because you are drawing lots of stuff manually:
-    // A) Make sure you are coarse clipping, because ImDrawList let all your vertices pass. You can use the Metrics window to inspect draw list contents.
-    // B) If you need/want meshes with more than 64K vertices, uncomment the '#define ImDrawIdx unsigned int' line in imconfig.h to set the index size to 4 bytes.
-    //    You'll need to handle the 4-bytes indices to your renderer. For example, the OpenGL example code detect index size at compile-time by doing:
-    //      glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer_offset);
-    //    Your own engine or render API may use different parameters or function calls to specify index sizes. 2 and 4 bytes indices are generally supported by most API.
-    // C) If for some reason you cannot use 4 bytes indices or don't want to, a workaround is to call BeginChild()/EndChild() before reaching the 64K limit to split your draw commands in multiple draw lists.
+    // - First, make sure you are coarse clipping yourself and not trying to draw many things outside visible bounds. 
+    //   Be mindful that the ImDrawList API doesn't filter vertices. Use the Metrics window to inspect draw list contents.
+    // - If you want large meshes with more than 64K vertices, you can either:
+    //   (A) Handle the ImDrawCmd::VtxOffset value in your renderer back-end, and set 'io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset'.
+    //       Most example back-ends already support this from 1.71. Pre-1.71 back-ends won't.
+    //       Some graphics API such as GL ES 1/2 don't have a way to offset the starting vertex so it is not supported for them.
+    //   (B) Or handle 32-bits indices in your renderer back-end, and uncomment '#define ImDrawIdx unsigned int' line in imconfig.h.
+    //       Most example back-ends already support this. For example, the OpenGL example code detect index size at compile-time:
+    //         glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer_offset);
+    //       Your own engine or render API may use different parameters or function calls to specify index sizes. 
+    //       2 and 4 bytes indices are generally supported by most graphics API.
+    // - If for some reason neither of those solutions works for you, a workaround is to call BeginChild()/EndChild() before reaching 
+    //   the 64K limit to split your draw commands in multiple draw lists.
     if (sizeof(ImDrawIdx) == 2)
         IM_ASSERT(draw_list->_VtxCurrentIdx < (1 << 16) && "Too many vertices in ImDrawList using 16-bit indices. Read comment above");
 
@@ -5531,7 +5545,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
 
         // Setup draw list and outer clipping rectangle
         window->DrawList->Clear();
-        window->DrawList->Flags = (g.Style.AntiAliasedLines ? ImDrawListFlags_AntiAliasedLines : 0) | (g.Style.AntiAliasedFill ? ImDrawListFlags_AntiAliasedFill : 0);
         window->DrawList->PushTextureID(g.Font->ContainerAtlas->TexID);
         PushClipRect(host_rect.Min, host_rect.Max, false);
 
@@ -9794,9 +9807,10 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                     continue;
                 }
                 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", (void*)(intptr_t)pcmd->TextureId, pcmd->ClipRect.x, pcmd->ClipRect.y, pcmd->ClipRect.z, pcmd->ClipRect.w);
+                char buf[300];
+                ImFormatString(buf, IM_ARRAYSIZE(buf), "Draw %4d triangles, tex 0x%p, clip_rect (%4.0f,%4.0f)-(%4.0f,%4.0f)",
+                    pcmd->ElemCount/3, (void*)(intptr_t)pcmd->TextureId, pcmd->ClipRect.x, pcmd->ClipRect.y, pcmd->ClipRect.z, pcmd->ClipRect.w);
+                bool pcmd_node_open = ImGui::TreeNode((void*)(pcmd - draw_list->CmdBuffer.begin()), "%s", buf);
                 if (show_drawcmd_clip_rects && fg_draw_list && ImGui::IsItemHovered())
                 {
                     ImRect clip_rect = pcmd->ClipRect;
@@ -9810,11 +9824,11 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                     continue;
 
                 // Display individual triangles/vertices. Hover on to get the corresponding triangle highlighted.
+                ImGui::Text("ElemCount: %d, ElemCount/3: %d, VtxOffset: +%d, IdxOffset: +%d", pcmd->ElemCount, pcmd->ElemCount/3, pcmd->VtxOffset, pcmd->IdxOffset);
                 ImGuiListClipper clipper(pcmd->ElemCount/3); // Manually coarse clip our print out of individual vertices to save CPU, only items that may be visible.
                 while (clipper.Step())
                     for (int prim = clipper.DisplayStart, idx_i = elem_offset + clipper.DisplayStart*3; prim < clipper.DisplayEnd; prim++)
                     {
-                        char buf[300];
                         char *buf_p = buf, *buf_end = buf + IM_ARRAYSIZE(buf);
                         ImVec2 triangles_pos[3];
                         for (int n = 0; n < 3; n++, idx_i++)
@@ -9823,7 +9837,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                             ImDrawVert& v = draw_list->VtxBuffer[vtx_i];
                             triangles_pos[n] = v.pos;
                             buf_p += ImFormatString(buf_p, buf_end - buf_p, "%s %04d: pos (%8.2f,%8.2f), uv (%.6f,%.6f), col %08X\n",
-                                (n == 0) ? "idx" : "   ", idx_i, v.pos.x, v.pos.y, v.uv.x, v.uv.y, v.col);
+                                (n == 0) ? "elem" : "    ", idx_i, v.pos.x, v.pos.y, v.uv.x, v.uv.y, v.col);
                         }
                         ImGui::Selectable(buf, false);
                         if (fg_draw_list && ImGui::IsItemHovered())

3rdparty/dear-imgui/imgui.h

@@ -47,7 +47,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.71 WIP"
-#define IMGUI_VERSION_NUM           17002
+#define IMGUI_VERSION_NUM           17003
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 
 // Define attributes of all API symbols declarations (e.g. for DLL under Windows)
@@ -219,9 +219,9 @@ namespace ImGui
     IMGUI_API ImDrawData*   GetDrawData();                              // valid after Render() and until the next call to NewFrame(). this is what you have to render.
 
     // Demo, Debug, Information
-    IMGUI_API void          ShowDemoWindow(bool* p_open = NULL);        // create demo/test window (previously called ShowTestWindow). demonstrate most ImGui features. call this to learn about the library! try to make it always available in your application!
-    IMGUI_API void          ShowAboutWindow(bool* p_open = NULL);       // create about window. display Dear ImGui version, credits and build/system information.
-    IMGUI_API void          ShowMetricsWindow(bool* p_open = NULL);     // create metrics/debug window. display Dear ImGui internals: draw commands (with individual draw calls and vertices), window list, basic internal state, etc.
+    IMGUI_API void          ShowDemoWindow(bool* p_open = NULL);        // create Demo window (previously called ShowTestWindow). demonstrate most ImGui features. call this to learn about the library! try to make it always available in your application!
+    IMGUI_API void          ShowAboutWindow(bool* p_open = NULL);       // create About window. display Dear ImGui version, credits and build/system information.
+    IMGUI_API void          ShowMetricsWindow(bool* p_open = NULL);     // create Metrics/Debug window. display Dear ImGui internals: draw commands (with individual draw calls and vertices), window list, basic internal state, etc.
     IMGUI_API void          ShowStyleEditor(ImGuiStyle* ref = NULL);    // add style editor block (not a window). you can pass in a reference ImGuiStyle structure to compare to, revert to and save to (else it uses the default style)
     IMGUI_API bool          ShowStyleSelector(const char* label);       // add style selector block (not a window), essentially a combo listing the default styles.
     IMGUI_API void          ShowFontSelector(const char* label);        // add font selector block (not a window), essentially a combo listing the loaded fonts.
@@ -1004,9 +1004,10 @@ enum ImGuiConfigFlags_
 enum ImGuiBackendFlags_
 {
     ImGuiBackendFlags_None                  = 0,
-    ImGuiBackendFlags_HasGamepad            = 1 << 0,   // Back-end supports gamepad and currently has one connected.
-    ImGuiBackendFlags_HasMouseCursors       = 1 << 1,   // Back-end supports honoring GetMouseCursor() value to change the OS cursor shape.
-    ImGuiBackendFlags_HasSetMousePos        = 1 << 2    // Back-end supports io.WantSetMousePos requests to reposition the OS mouse position (only used if ImGuiConfigFlags_NavEnableSetMousePos is set).
+    ImGuiBackendFlags_HasGamepad            = 1 << 0,   // Back-end Platform supports gamepad and currently has one connected.
+    ImGuiBackendFlags_HasMouseCursors       = 1 << 1,   // Back-end Platform supports honoring GetMouseCursor() value to change the OS cursor shape.
+    ImGuiBackendFlags_HasSetMousePos        = 1 << 2,   // Back-end Platform supports io.WantSetMousePos requests to reposition the OS mouse position (only used if ImGuiConfigFlags_NavEnableSetMousePos is set).
+    ImGuiBackendFlags_RendererHasVtxOffset  = 1 << 3    // Back-end Renderer supports ImDrawCmd::VtxOffset. This enables output of large meshes (64K+ vertices) while still using 16-bits indices.
 };
 
 // Enumeration for PushStyleColor() / PopStyleColor()
@@ -1772,25 +1773,31 @@ struct ImColor
 // The expected behavior from your rendering function is 'if (cmd.UserCallback != NULL) { cmd.UserCallback(parent_list, cmd); } else { RenderTriangles() }'
 typedef void (*ImDrawCallback)(const ImDrawList* parent_list, const ImDrawCmd* cmd);
 
-// Special Draw Callback value to request renderer back-end to reset the graphics/render state.
+// Special Draw callback value to request renderer back-end to reset the graphics/render state.
 // The renderer back-end needs to handle this special value, otherwise it will crash trying to call a function at this address.
 // This is useful for example if you submitted callbacks which you know have altered the render state and you want it to be restored.
 // It is not done by default because they are many perfectly useful way of altering render state for imgui contents (e.g. changing shader/blending settings before an Image call).
 #define ImDrawCallback_ResetRenderState     (ImDrawCallback)(-1)
 
 // Typically, 1 command = 1 GPU draw call (unless command is a callback)
+// Pre 1.71 back-ends will typically ignore the VtxOffset/IdxOffset fields. When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset'
+// is enabled, those fields allow us to render meshes larger than 64K vertices while keeping 16-bits indices.
 struct ImDrawCmd
 {
     unsigned int    ElemCount;              // Number of indices (multiple of 3) to be rendered as triangles. Vertices are stored in the callee ImDrawList's vtx_buffer[] array, indices in idx_buffer[].
     ImVec4          ClipRect;               // Clipping rectangle (x1, y1, x2, y2). Subtract ImDrawData->DisplayPos to get clipping rectangle in "viewport" coordinates
     ImTextureID     TextureId;              // User-provided texture ID. Set by user in ImfontAtlas::SetTexID() for fonts or passed to Image*() functions. Ignore if never using images or multiple fonts atlas.
+    unsigned int    VtxOffset;              // Start offset in vertex buffer. Pre-1.71 or without ImGuiBackendFlags_RendererHasVtxOffset: always 0. With ImGuiBackendFlags_RendererHasVtxOffset: may be >0 to support meshes larger than 64K vertices with 16-bits indices.
+    unsigned int    IdxOffset;              // Start offset in index buffer. Always equal to sum of ElemCount drawn so far.
     ImDrawCallback  UserCallback;           // If != NULL, call the function instead of rendering the vertices. clip_rect and texture_id will be set normally.
     void*           UserCallbackData;       // The draw callback code can access this.
 
-    ImDrawCmd() { ElemCount = 0; ClipRect.x = ClipRect.y = ClipRect.z = ClipRect.w = 0.0f; TextureId = (ImTextureID)NULL; UserCallback = NULL; UserCallbackData = NULL; }
+    ImDrawCmd() { ElemCount = 0; ClipRect.x = ClipRect.y = ClipRect.z = ClipRect.w = 0.0f; TextureId = (ImTextureID)NULL; VtxOffset = IdxOffset = 0;  UserCallback = NULL; UserCallbackData = NULL; }
 };
 
-// Vertex index (override with '#define ImDrawIdx unsigned int' in imconfig.h)
+// Vertex index 
+// (to allow large meshes with 16-bits indices: set 'io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset' and handle ImDrawCmd::VtxOffset in the renderer back-end)
+// (to use 32-bits indices: override with '#define ImDrawIdx unsigned int' in imconfig.h)
 #ifndef ImDrawIdx
 typedef unsigned short ImDrawIdx;
 #endif
@@ -1836,7 +1843,8 @@ enum ImDrawListFlags_
 {
     ImDrawListFlags_None             = 0,
     ImDrawListFlags_AntiAliasedLines = 1 << 0,  // Lines are anti-aliased (*2 the number of triangles for 1.0f wide line, otherwise *3 the number of triangles)
-    ImDrawListFlags_AntiAliasedFill  = 1 << 1   // Filled shapes have anti-aliased edges (*2 the number of vertices)
+    ImDrawListFlags_AntiAliasedFill  = 1 << 1,  // Filled shapes have anti-aliased edges (*2 the number of vertices)
+    ImDrawListFlags_AllowVtxOffset   = 1 << 2   // Can emit 'VtxOffset > 0' to allow large meshes. Set when 'ImGuiBackendFlags_RendererHasVtxOffset' is enabled.
 };
 
 // Draw command list
@@ -1856,7 +1864,8 @@ struct ImDrawList
     // [Internal, used while building lists]
     const ImDrawListSharedData* _Data;          // Pointer to shared draw data (you can use ImGui::GetDrawListSharedData() to get the one from current ImGui context)
     const char*             _OwnerName;         // Pointer to owner window's name for debugging
-    unsigned int            _VtxCurrentIdx;     // [Internal] == VtxBuffer.Size
+    unsigned int            _VtxCurrentOffset;  // [Internal] Always 0 unless 'Flags & ImDrawListFlags_AllowVtxOffset'.
+    unsigned int            _VtxCurrentIdx;     // [Internal] Generally == VtxBuffer.Size unless we are past 64K vertices, in which case this gets reset to 0.
     ImDrawVert*             _VtxWritePtr;       // [Internal] point within VtxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
     ImDrawIdx*              _IdxWritePtr;       // [Internal] point within IdxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
     ImVector<ImVec4>        _ClipRectStack;     // [Internal]

3rdparty/dear-imgui/imgui_demo.cpp

@@ -350,6 +350,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
             ImGui::CheckboxFlags("io.BackendFlags: HasGamepad", (unsigned int *)&backend_flags, ImGuiBackendFlags_HasGamepad);
             ImGui::CheckboxFlags("io.BackendFlags: HasMouseCursors", (unsigned int *)&backend_flags, ImGuiBackendFlags_HasMouseCursors);
             ImGui::CheckboxFlags("io.BackendFlags: HasSetMousePos", (unsigned int *)&backend_flags, ImGuiBackendFlags_HasSetMousePos);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasVtxOffset", (unsigned int *)&backend_flags, ImGuiBackendFlags_RendererHasVtxOffset);
             ImGui::TreePop();
             ImGui::Separator();
         }
@@ -2862,6 +2863,7 @@ void ImGui::ShowAboutWindow(bool* p_open)
         if (io.BackendFlags & ImGuiBackendFlags_HasGamepad)             ImGui::Text(" HasGamepad");
         if (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors)        ImGui::Text(" HasMouseCursors");
         if (io.BackendFlags & ImGuiBackendFlags_HasSetMousePos)         ImGui::Text(" HasSetMousePos");
+        if (io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)   ImGui::Text(" RendererHasVtxOffset");
         ImGui::Separator();
         ImGui::Text("io.Fonts: %d fonts, Flags: 0x%08X, TexSize: %d,%d", io.Fonts->Fonts.Size, io.Fonts->Flags, io.Fonts->TexWidth, io.Fonts->TexHeight);
         ImGui::Text("io.DisplaySize: %.2f,%.2f", io.DisplaySize.x, io.DisplaySize.y);

3rdparty/dear-imgui/imgui_draw.cpp

@@ -348,6 +348,7 @@ ImDrawListSharedData::ImDrawListSharedData()
     FontSize = 0.0f;
     CurveTessellationTol = 0.0f;
     ClipRectFullscreen = ImVec4(-8192.0f, -8192.0f, +8192.0f, +8192.0f);
+    InitialFlags = ImDrawListFlags_None;
 
     // Const data
     for (int i = 0; i < IM_ARRAYSIZE(CircleVtx12); i++)
@@ -362,7 +363,8 @@ void ImDrawList::Clear()
     CmdBuffer.resize(0);
     IdxBuffer.resize(0);
     VtxBuffer.resize(0);
-    Flags = ImDrawListFlags_AntiAliasedLines | ImDrawListFlags_AntiAliasedFill;
+    Flags = _Data->InitialFlags;
+    _VtxCurrentOffset = 0;
     _VtxCurrentIdx = 0;
     _VtxWritePtr = NULL;
     _IdxWritePtr = NULL;
@@ -415,6 +417,8 @@ void ImDrawList::AddDrawCmd()
     ImDrawCmd draw_cmd;
     draw_cmd.ClipRect = GetCurrentClipRect();
     draw_cmd.TextureId = GetCurrentTextureId();
+    draw_cmd.VtxOffset = _VtxCurrentOffset;
+    draw_cmd.IdxOffset = IdxBuffer.Size;
 
     IM_ASSERT(draw_cmd.ClipRect.x <= draw_cmd.ClipRect.z && draw_cmd.ClipRect.y <= draw_cmd.ClipRect.w);
     CmdBuffer.push_back(draw_cmd);
@@ -603,6 +607,14 @@ void ImDrawList::ChannelsSetCurrent(int idx)
 // NB: this can be called with negative count for removing primitives (as long as the result does not underflow)
 void ImDrawList::PrimReserve(int idx_count, int vtx_count)
 {
+    // Large mesh support (when enabled)
+    if (sizeof(ImDrawIdx) == 2 && (_VtxCurrentIdx + vtx_count >= (1 << 16)) && (Flags & ImDrawListFlags_AllowVtxOffset))
+    {
+        _VtxCurrentOffset = VtxBuffer.Size;
+        _VtxCurrentIdx = 0;
+        AddDrawCmd();
+    }
+
     ImDrawCmd& draw_cmd = CmdBuffer.Data[CmdBuffer.Size-1];
     draw_cmd.ElemCount += idx_count;
 
@@ -2949,7 +2961,7 @@ void ImFont::RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col
     draw_list->CmdBuffer[draw_list->CmdBuffer.Size-1].ElemCount -= (idx_expected_size - draw_list->IdxBuffer.Size);
     draw_list->_VtxWritePtr = vtx_write;
     draw_list->_IdxWritePtr = idx_write;
-    draw_list->_VtxCurrentIdx = (unsigned int)draw_list->VtxBuffer.Size;
+    draw_list->_VtxCurrentIdx = vtx_current_idx;
 }
 
 //-----------------------------------------------------------------------------

3rdparty/dear-imgui/imgui_internal.h

@@ -731,6 +731,7 @@ struct IMGUI_API ImDrawListSharedData
     float           FontSize;                   // Current/default font size (optional, for simplified AddText overload)
     float           CurveTessellationTol;
     ImVec4          ClipRectFullscreen;         // Value for PushClipRectFullscreen()
+    ImDrawListFlags InitialFlags;               // Initial flags at the beginning of the frame (it is possible to alter flags on a per-drawlist basis afterwards)
 
     // Const data
     // FIXME: Bake rounded corners fill/borders in atlas
@@ -1034,7 +1035,7 @@ struct ImGuiContext
     int                     WantTextInputNextFrame;
     char                    TempBuffer[1024*3+1];               // Temporary text buffer
 
-    ImGuiContext(ImFontAtlas* shared_font_atlas) : BackgroundDrawList(NULL), ForegroundDrawList(NULL)
+    ImGuiContext(ImFontAtlas* shared_font_atlas) : BackgroundDrawList(&DrawListSharedData), ForegroundDrawList(&DrawListSharedData)
     {
         Initialized = false;
         FrameScopeActive = FrameScopePushedImplicitWindow = false;
@@ -1109,9 +1110,7 @@ struct ImGuiContext
         FocusTabPressed = false;
 
         DimBgRatio = 0.0f;
-        BackgroundDrawList._Data = &DrawListSharedData;
         BackgroundDrawList._OwnerName = "##Background"; // Give it a name for debugging
-        ForegroundDrawList._Data = &DrawListSharedData;
         ForegroundDrawList._OwnerName = "##Foreground"; // Give it a name for debugging
         MouseCursor = ImGuiMouseCursor_Arrow;