Migrated to OGRE's built-in DearIMGUI

STATUS:
- ogre imgui port: keyboard/mouse input working!
- ogre imgui port: FIXME: hacked Renderdash to build, but imgui will likely render into it - how to disable??
- ogre imgui port: builds and runs with default font.
- under Debug I get asserts about NewFrame()/EndFrame() mismatches, to be fixed later.

CODECHANGES:
* imgui deprecated - renamed ImGui::AlignFirstTextHeightToWidgets() to ImGui::AlignTextToFramePadding()
* imgui deprecated - ImGui::GetContentRegionAvailWidth() -> use ImGui::GetContentRegionAvail().x
* imgui deprecated -  GetWindowContentRegionWidth() function. -> 'GetWindowContentRegionMax().x
* imgui deprecated - SetScrollHere() -> SetScrollHereX() + SetScollHereY()
* imgui deprecated - ImGui::TreeAdvanceToLabelPos()      -> use ImGui::SetCursorPosX(ImGui::GetCursorPosX() + ImGui::GetTreeNodeToLabelSpacing());
* imgui deprecated - renamed SetNextTreeNodeOpen() to SetNextItemOpen().
* imgui deprecated - renamed ListBoxHeader(const char* label, ImVec2 size) to BeginListBox().
* imgui deprecated - removed BeginPopupContextWindow(const char*, int mouse_button, bool also_over_items) in favor of BeginPopupContextWindow(const char*, ImGuiPopupFlags flags) with ImGuiPopupFlags_NoOverItems.
* imgui deprecated - removed CalcListClipping() function. Prefer using ImGuiListClipper which can return non-contiguous ranges.
* imgui deprecated - ImGuiCol_ChildWindowBg              -> use ImGuiCol_ChildBg
* imgui deprecated - style: renamed ImGuiCol_ModalWindowDarkening to ImGuiCol_ModalWindowDimBg
* imgui deprecated - GetItemsLineHeightWithSpacing()     -> use GetFrameHeightWithSpacing()
* imgui deprecated - InputText: Renamed  ImGuiTextEditCallbackData to ImGuiInputTextCallbackData
* imgui deprecated - SetNextWindowContentWidth(float w)    ->    SetNextWindowContentSize(ImVec2(w, 0.0f))
* imgui deprecated - SetNextWindowPosCenter(ImGuiCond c=0) { SetNextWindowPos(GetMainViewport()->GetCenter(), c, ImVec2(0.5f,0.5f));
* ogre imgui port: use public `GetFont()/GetFontSize()` instead of internal `ImGuiContext->Font/FontSize`
* VehicleAI panel: `Push/PopItemFlag(Disabled)` (imgui_internal) -> `Begin/EndDisabled()` (public BETA API)

source/main/AppContext.cpp

@@ -75,7 +75,7 @@ bool AppContext::SetUpInput()
 bool AppContext::mouseMoved(const OgreBites::MouseMotionEvent& arg) // overrides OgreBites::InputListener
 {
     App::GetGuiManager()->WakeUpGUI();
-    App::GetGuiManager()->GetImGui().InjectMouseMoved(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->mouseMoved(arg);
 
     if (!ImGui::GetIO().WantCaptureMouse) // true if mouse is over any window
     {
@@ -99,7 +99,7 @@ bool AppContext::mouseMoved(const OgreBites::MouseMotionEvent& arg) // overrides
 bool AppContext::mouseWheelRolled(const OgreBites::MouseWheelEvent& arg)
 {
     App::GetGuiManager()->WakeUpGUI();
-    App::GetGuiManager()->GetImGui().InjectMouseWheelRolled(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->mouseWheelRolled(arg);
 
     if (!ImGui::GetIO().WantCaptureMouse) // true if mouse is over any window
     {
@@ -112,7 +112,7 @@ bool AppContext::mouseWheelRolled(const OgreBites::MouseWheelEvent& arg)
 bool AppContext::mousePressed(const OgreBites::MouseButtonEvent& arg) // overrides OgreBites::InputListener
 {
     App::GetGuiManager()->WakeUpGUI();
-    App::GetGuiManager()->GetImGui().InjectMousePressed(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->mousePressed(arg);
 
     if (!ImGui::GetIO().WantCaptureMouse) // true if mouse is over any window
     {
@@ -135,7 +135,7 @@ bool AppContext::mousePressed(const OgreBites::MouseButtonEvent& arg) // overrid
 bool AppContext::mouseReleased(const OgreBites::MouseButtonEvent& arg) // overrides OgreBites::InputListener
 {
     App::GetGuiManager()->WakeUpGUI();
-    App::GetGuiManager()->GetImGui().InjectMouseReleased(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->mouseReleased(arg);
 
     if (!ImGui::GetIO().WantCaptureMouse) // true if mouse is over any window
     {
@@ -155,7 +155,7 @@ bool AppContext::mouseReleased(const OgreBites::MouseButtonEvent& arg) // overri
 
 bool AppContext::keyPressed(const OgreBites::KeyboardEvent& arg)
 {
-    App::GetGuiManager()->GetImGui().InjectKeyPressed(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->keyPressed(arg);
 
     if (!App::GetGuiManager()->IsGuiCaptureKeyboardRequested() &&
         !ImGui::GetIO().WantCaptureKeyboard)
@@ -168,7 +168,7 @@ bool AppContext::keyPressed(const OgreBites::KeyboardEvent& arg)
 
 bool AppContext::keyReleased(const OgreBites::KeyboardEvent& arg)
 {
-    App::GetGuiManager()->GetImGui().InjectKeyReleased(arg);
+    App::GetGuiManager()->GetImGuiInputListener()->keyReleased(arg);
 
     if (!App::GetGuiManager()->IsGuiCaptureKeyboardRequested() &&
         !ImGui::GetIO().WantCaptureKeyboard)

source/main/CMakeLists.txt

@@ -99,17 +99,6 @@ set(SOURCE_FILES
         gui/GUIUtils.{h,cpp}
         gui/OverlayWrapper.{h,cpp}
         gui/RTTLayer.{h,cpp}
-        gui/imgui/imgui.{h,cpp}
-        gui/imgui/imgui_demo.cpp
-        gui/imgui/imgui_draw.cpp
-        gui/imgui/imgui_widgets.cpp
-        gui/imgui/OgreImGuiOverlay.{h,cpp}
-        gui/imgui/OgreImGui.{h,cpp}
-        gui/imgui/imconfig.h
-        gui/imgui/imgui_internal.h
-        gui/imgui/imstb_rectpack.h
-        gui/imgui/imstb_textedit.h
-        gui/imgui/imstb_truetype.h
         gui/panels/GUI_AngelScriptExamples.{h,cpp}
         gui/panels/GUI_CollisionsDebug.{h,cpp}
         gui/panels/GUI_ConsoleView.{h,cpp}
@@ -323,7 +312,6 @@ target_include_directories(${BINNAME} PRIVATE
         gfx/particle
         gfx/skyx
         gui
-        gui/imgui
         gui/mygui
         gui/panels
         network

source/main/gfx/GfxActor.cpp

@@ -39,7 +39,7 @@
 #include "InputEngine.h" // TODO: Keys shouldn't be queried from here, but buffered in sim. loop ~ only_a_ptr, 06/2018
 #include "MeshObject.h"
 #include "MovableText.h"
-#include "OgreImGui.h"
+
 #include "Renderdash.h" // classic 'renderdash' material
 #include "ActorSpawner.h"
 #include "SlideNode.h"
@@ -50,7 +50,7 @@
 #include "TurboProp.h"
 #include "Utils.h"
 
-#include "imgui_internal.h"
+
 
 #include <Ogre.h>
 

source/main/gfx/GfxScene.cpp

@@ -39,7 +39,7 @@
 #include "TerrainObjectManager.h"
 #include "Utils.h"
 
-#include "imgui_internal.h"
+
 
 #include <Ogre.h>
 
@@ -369,7 +369,6 @@ void GfxScene::DrawNetLabel(Ogre::Vector3 scene_pos, float cam_dist, std::string
         GUIManager::GuiTheme const& theme = App::GetGuiManager()->GetTheme();
 
         ImDrawList* drawlist = GetImDummyFullscreenWindow();
-        ImGuiContext* g = ImGui::GetCurrentContext();
 
         ImVec2 text_pos(pos.x - ((text_size.x / 2)), pos.y - ((text_size.y / 2)));
 
@@ -384,7 +383,7 @@ void GfxScene::DrawNetLabel(Ogre::Vector3 scene_pos, float cam_dist, std::string
         // draw colored text
         Ogre::ColourValue color = App::GetNetwork()->GetPlayerColor(colornum);
         ImVec4 text_color(color.r, color.g, color.b, 1.f);
-        drawlist->AddText(g->Font, g->FontSize, text_pos, ImColor(text_color), caption.c_str());
+        drawlist->AddText(ImGui::GetFont(), ImGui::GetFontSize(), text_pos, ImColor(text_color), caption.c_str());
     }
 }
 

source/main/gfx/Renderdash.cpp

@@ -93,7 +93,8 @@ void RoR::Renderdash::preRenderTargetUpdate(const Ogre::RenderTargetEvent& evt)
     App::GetGfxScene()->GetSceneManager()->setFindVisibleObjects(false);
 
     // Disable DearIMGUI overlay
-    App::GetGfxScene()->GetSceneManager()->removeRenderQueueListener(&App::GetGuiManager()->GetImGui());
+    // FIXME: how to prevent OGRE builtin IMGUI from rendering to renderdash?
+//    App::GetGfxScene()->GetSceneManager()->removeRenderQueueListener(App::GetGuiManager()->GetImGui());
 
     // Disable other overlays
     App::GetOverlayWrapper()->HideRacingOverlay();
@@ -111,7 +112,8 @@ void RoR::Renderdash::postRenderTargetUpdate(const Ogre::RenderTargetEvent& evt)
     App::GetGfxScene()->GetSceneManager()->setFindVisibleObjects(true);
 
     // Enable DearIMGUI overlay
-    App::GetGfxScene()->GetSceneManager()->addRenderQueueListener(&App::GetGuiManager()->GetImGui());
+    // FIXME: how to prevent OGRE builtin IMGUI from rendering to renderdash?
+//    App::GetGfxScene()->GetSceneManager()->addRenderQueueListener(&App::GetGuiManager()->GetImGui());
 
     // Overlays 'racing' and 'direction arrow' are re-enabled automatically if needed
 

source/main/gui/GUIManager.cpp

@@ -33,7 +33,7 @@
 #include "GUIUtils.h"
 #include "InputEngine.h"
 #include "Language.h"
-#include "OgreImGui.h"
+
 #include "OverlayWrapper.h"
 #include "PlatformUtils.h"
 #include "RTTLayer.h"
@@ -310,23 +310,40 @@ void GUIManager::NewImGuiFrame(float dt)
     io.KeySuper = false;
 
     // Call IMGUI
-    Ogre::FrameEvent ev;
-    ev.timeSinceLastFrame = dt;
-    Ogre::ImGuiOverlay::NewFrame(ev);
+    Ogre::ImGuiOverlay::NewFrame();
 
     // Reset state
     m_gui_kb_capture_queued = false;
 }
 
 void GUIManager::SetupImGui()
 {
-    m_imgui.Init();
+    // Initialize OGRE's builtin DearIMGUI
+    // see OGRE source file '/Samples/Simple/include/ImGuiDemo.h'
+    m_imgui_overlay = new Ogre::ImGuiOverlay();
+
+    // handle DPI scaling
+    float vpScale = Ogre::OverlayManager::getSingleton().getPixelRatio();
+    ImGui::GetIO().FontGlobalScale = std::round(vpScale); // default font does not work with fractional scaling
+    ImGui::GetStyle().ScaleAllSizes(vpScale);
+
+    m_imgui_overlay->setZOrder(300);
+    m_imgui_overlay->show();
+    Ogre::OverlayManager::getSingleton().addOverlay(m_imgui_overlay); // now owned by overlaymgr
+
+    // NOTE:
+    // Custom apps will ASSERT on ImGuiOverlay::NewFrame() and not display any UI if they
+    //  have not registered the overlay system by calling mSceneMgr->addRenderQueueListener(mOverlaySystem).
+    // Rigs of Rods does this in main().
+
+    m_imgui_input_listener = new OgreBites::ImGuiInputListener();
+
     // Colors
     ImGuiStyle& style = ImGui::GetStyle();
     style.Colors[ImGuiCol_Text]                  = ImVec4(0.90f, 0.90f, 0.90f, 1.00f);
     style.Colors[ImGuiCol_TextDisabled]          = ImVec4(0.60f, 0.60f, 0.60f, 1.00f);
     style.Colors[ImGuiCol_WindowBg]              = ImVec4(0.06f, 0.06f, 0.06f, 0.90f);
-    style.Colors[ImGuiCol_ChildWindowBg]         = ImVec4(0.00f, 0.00f, 0.00f, 0.1f);
+    style.Colors[ImGuiCol_ChildBg]               = ImVec4(0.00f, 0.00f, 0.00f, 0.1f);
     style.Colors[ImGuiCol_PopupBg]               = ImVec4(0.05f, 0.05f, 0.10f, 0.90f);
     style.Colors[ImGuiCol_Border]                = ImVec4(0.20f, 0.20f, 0.20f, 0.90f);
     style.Colors[ImGuiCol_BorderShadow]          = ImVec4(0.00f, 0.00f, 0.00f, 0.90f);
@@ -358,7 +375,7 @@ void GUIManager::SetupImGui()
     style.Colors[ImGuiCol_PlotHistogram]         = ImVec4(0.18f, 0.53f, 0.79f, 0.90f);
     style.Colors[ImGuiCol_PlotHistogramHovered]  = ImVec4(0.13f, 0.40f, 0.60f, 0.90f);
     style.Colors[ImGuiCol_TextSelectedBg]        = ImVec4(0.00f, 0.00f, 1.00f, 0.90f);
-    style.Colors[ImGuiCol_ModalWindowDarkening]  = ImVec4(0.20f, 0.20f, 0.20f, 0.90f);
+    style.Colors[ImGuiCol_ModalWindowDimBg]      = ImVec4(0.20f, 0.20f, 0.20f, 0.90f);
     // Styles
     style.WindowPadding         = ImVec2(10.f, 10.f);
     style.FrameRounding         = 2.f;
@@ -367,8 +384,6 @@ void GUIManager::SetupImGui()
     style.ItemSpacing           = ImVec2(5.f, 5.f);
     style.GrabRounding          = 3.f;
     style.WindowBorderSize      = 0.f;
-
-    App::GetGfxScene()->GetSceneManager()->addRenderQueueListener(&m_imgui);
 }
 
 void GUIManager::DrawCommonGui()

source/main/gui/GUIManager.h

@@ -24,9 +24,9 @@
 
 #pragma once
 
-#include "OgreImGui.h"
+
 #include "Application.h"
-#include "GUI_MessageBox.h"
+#include "GUIUtils.h"
 
 // GUI panels
 #include "GUI_CollisionsDebug.h"
@@ -55,11 +55,13 @@
 #include "GUI_VehicleButtons.h"
 
 // Deps
+#include <Bites/OgreImGuiInputListener.h>
 #include <Bites/OgreWindowEventUtilities.h>
 #include <MyGUI.h>
 #include <MyGUI_OgrePlatform.h>
 #include <MyGUI_UString.h>
 #include <OgreOverlay.h>
+#include <OgreImGuiOverlay.h>
 
 namespace RoR {
 
@@ -154,7 +156,8 @@ class GUIManager: public ZeroedMemoryAllocator
 
     void SetUpMenuWallpaper();
 
-    inline OgreImGui& GetImGui() { return m_imgui; }
+    inline Ogre::ImGuiOverlay* GetImGui() { return m_imgui_overlay; }
+    OgreBites::ImGuiInputListener* GetImGuiInputListener() { return m_imgui_input_listener; }
     inline GuiTheme&  GetTheme() { return m_theme; }
 
     void WakeUpGUI();
@@ -169,12 +172,15 @@ class GUIManager: public ZeroedMemoryAllocator
     MyGUI::Gui*          m_mygui                    = nullptr;
     MyGUI::OgrePlatform* m_mygui_platform           = nullptr;
     bool                 m_hide_gui                 = false;
-    OgreImGui            m_imgui;
     GuiTheme             m_theme;
     bool                 m_gui_kb_capture_queued    = false; //!< Resets and accumulates every frame
     bool                 m_gui_kb_capture_requested = false; //!< Effective value, persistent
     Ogre::Timer          m_last_mousemove_time;
     bool                 m_is_cursor_supressed      = false; //!< True if cursor was manually hidden.
+
+    // DearIMGUI integration
+    Ogre::ImGuiOverlay* m_imgui_overlay = nullptr;
+    OgreBites::ImGuiInputListener* m_imgui_input_listener = nullptr;
 };
 
 } // namespace RoR