Detect wayland sessions and report a clear error prompting users to switch to X11 or choose a different graphics mode

PiperOrigin-RevId: 904460146
Change-Id: I9324f403cb09787833c06f863ac157059eea60e7

src/experimental/platform/hal/window.cc

@@ -16,6 +16,7 @@
 
 #include <algorithm>
 #include <cstddef>
+#include <cstdlib>
 #include <span>
 #include <string>
 #include <string_view>

src/experimental/studio/main.cc

@@ -75,7 +75,7 @@ class FileResource {
 int main(int argc, char** argv, char** envp) {
   absl::ParseCommandLine(argc, argv);
 
-  const char* home = getenv("HOME");
+  const char* home = std::getenv("HOME");
   const std::string ini_path = std::string(home ? home : ".") + "/.mujoco.ini";
 
   mjpResourceProvider resource_provider;
@@ -103,6 +103,20 @@ int main(int argc, char** argv, char** envp) {
 
   std::string gfx = absl::GetFlag(FLAGS_gfx);
 
+  const char* session_type = std::getenv("XDG_SESSION_TYPE");
+  const char* wayland_display = std::getenv("WAYLAND_DISPLAY");
+  if ((session_type && std::string_view(session_type) == "wayland") ||
+      wayland_display) {
+    if (gfx.empty()) {
+      gfx = "opengl_headless";
+    } else if (gfx == "classic" || gfx == "opengl") {
+      mju_error(
+          "Wayland does not support '%s' graphics mode. "
+          "Restart with a different graphics mode, or login using X11.",
+          gfx.c_str());
+    }
+  }
+
   mujoco::platform::GraphicsMode gfx_mode =
       mujoco::platform::GraphicsModeFromString(
           gfx, mujoco::platform::GraphicsMode::FilamentOpenGl);