From 917309e99c3784c18029db1da78de0f5e88e8a04 Mon Sep 17 00:00:00 2001
From: Patrick Wuttke <mewin@mewin.de>
Date: Sat, 20 Sep 2025 15:28:08 +0200
Subject: [PATCH] Prefer SDL X11 video driver on Linux for ImGui viewport
 support.

---
 private/raid/SModule         |  2 +-
 private/raid/application.cpp | 33 +++++++++++++++++++++++++++++++--
 public/raid/raid.hpp         |  1 +
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/private/raid/SModule b/private/raid/SModule
index 3f09d28..b0efdda 100644
--- a/private/raid/SModule
+++ b/private/raid/SModule
@@ -4,7 +4,7 @@ import json
 Import('env')
 
 if not hasattr(env, 'Jinja'):
-    env.Error('RAID requires the Jinja tool.')
+    env.Error('RAID requires Jinja.')
 
 src_files = Split("""
     application.cpp
diff --git a/private/raid/application.cpp b/private/raid/application.cpp
index 32fb999..cdc27e5 100644
--- a/private/raid/application.cpp
+++ b/private/raid/application.cpp
@@ -13,6 +13,7 @@
 #include <mijin/virtual_filesystem/mapping.hpp>
 #include <mijin/virtual_filesystem/relative.hpp>
 #include <imgui.h>
+#include <imgui_internal.h>
 #include <backends/imgui_impl_opengl3.h>
 #include <backends/imgui_impl_sdl3.h>
 #include <stb_image.h>
@@ -289,6 +290,11 @@ void Application::handleSDLEvent(const SDL_Event& event)
     }
 }
 
+void Application::handleSDLError(const char* message)
+{
+    msgError("SDL: {}", message);
+}
+
 bool Application::init()
 {
     auto addConfigDir = [&](const fs::path& path)
@@ -419,12 +425,19 @@ void Application::cleanup()
 
 bool Application::initSDL()
 {
-    if (!SDL_Init(0))
+#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
+    // prefer x11 over wayland, as ImGui viewports don't work with wayland
+    // TODO: this still doesn't work all the time, maybe there will be an update to ImGui in the future?
+    SDL_SetHint(SDL_HINT_VIDEO_DRIVER, "x11,wayland");
+#endif
+    if (!SDL_Init(SDL_INIT_VIDEO))
     {
         msgError("Error initializing SDL: {}.", SDL_GetError());
         return false;
     }
 
+    msgInfo("SDL video driver: {}", SDL_GetCurrentVideoDriver());
+
     // GL attributes must be set before window creation
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
@@ -475,12 +488,18 @@ bool Application::initImGui()
 {
     IMGUI_CHECKVERSION(); // not exactly useful when using static libs, but won't hurt
 
-    if (ImGui::CreateContext() == nullptr)
+    ImGuiContext* imguiContext = ImGui::CreateContext();
+    if (imguiContext == nullptr)
     {
         msgError("Error initializing ImGui context.");
         return false;
     }
 
+    imguiContext->ErrorCallbackUserData = this;
+    imguiContext->ErrorCallback = [](ImGuiContext* /* ctx */, void* userData, const char* msg) {
+        static_cast<Application*>(userData)->handleSDLError(msg);
+    };
+
     loadImGuiConfig();
 
     configureImgui();
@@ -503,6 +522,16 @@ bool Application::initImGui()
         return false;
     }
 
+    if (imguiIO.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        if (!(imguiIO.BackendFlags & ImGuiBackendFlags_PlatformHasViewports)) {
+            msgWarning("ImGUI viewports enabled, but platform doesn't support them.");
+        }
+        if (!(imguiIO.BackendFlags & ImGuiBackendFlags_RendererHasViewports)) {
+            msgWarning("ImGUI viewports enabled, but renderer doesn't support them.");
+        }
+    }
+
     // init font
     if (imguiIO.Fonts->Fonts.empty())
     {
diff --git a/public/raid/raid.hpp b/public/raid/raid.hpp
index 8fcd33a..5a1f54b 100644
--- a/public/raid/raid.hpp
+++ b/public/raid/raid.hpp
@@ -138,6 +138,7 @@ protected:
     virtual void initMemoryFS();
     virtual void handleMessage(const Message& message);
     virtual void handleSDLEvent(const SDL_Event& event);
+    virtual void handleSDLError(const char* message);
 
     void msgInfo(const char* text)
     {