Added build-stamp watermark

Extract the build watermark into its own BuildStampOverlay (rex/ui/overlay/build_stamp_overlay.*), a non-interactive drawer in the lower-left corner - independent of the F3 debug overlay. It stamps the short git commit hash (REXGLUE_GIT_HASH, captured by CMake via git rev-parse --short HEAD -> version.h; re-run cmake to refresh) via REXGLUE_BUILD_HASH_STAMP, instead of the build date. Drawing is gated by the show_build_stamp cvar (category UI, default true) so players can hide it; registered next to the other built-in overlays in rex_app.

thirdparty/rexglue-sdk/CMakeLists.txt

@@ -136,6 +136,17 @@ add_compile_definitions(REXGLUE_BUILD_CONFIG="$<CONFIG>")
 # Generate version header -- must run after REX_PLATFORM is set
 # Timestamp is set at configure time -- intentionally not updated on every rebuild
 string(TIMESTAMP REXGLUE_BUILD_TIMESTAMP "%Y%m%d_%H%M")
+# Short git commit hash of the containing project (re-run cmake to refresh it).
+execute_process(
+    COMMAND git rev-parse --short HEAD
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE REXGLUE_GIT_HASH
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+    ERROR_QUIET
+)
+if(NOT REXGLUE_GIT_HASH)
+    set(REXGLUE_GIT_HASH "nogit")
+endif()
 configure_file(
     ${CMAKE_CURRENT_SOURCE_DIR}/include/rex/version.h.in
     ${CMAKE_CURRENT_BINARY_DIR}/include/rex/version.h

thirdparty/rexglue-sdk/include/rex/rex_app.h

@@ -23,6 +23,7 @@
 #include <rex/ui/imgui_dialog.h>
 #include <rex/ui/imgui_drawer.h>
 #include <rex/ui/immediate_drawer.h>
+#include <rex/ui/overlay/build_stamp_overlay.h>
 #include <rex/ui/overlay/debug_overlay.h>
 #include <rex/ui/window.h>
 #include <rex/ui/window_listener.h>
@@ -139,6 +140,7 @@ class ReXApp : public ui::WindowedApp, public ui::WindowListener, public ui::Win
   // Built-in overlays
   std::shared_ptr<LogCaptureSink> log_sink_;
   std::unique_ptr<ui::DebugOverlayDialog> debug_overlay_;
+  std::unique_ptr<ui::BuildStampOverlay> build_stamp_overlay_;
   std::unique_ptr<ui::ConsoleDialog> console_overlay_;
   std::unique_ptr<ui::SettingsDialog> settings_overlay_;
 };

thirdparty/rexglue-sdk/include/rex/ui/overlay/build_stamp_overlay.h

@@ -0,0 +1,26 @@
+/**
+ * @file        rex/ui/overlay/build_stamp_overlay.h
+ * @brief       Always-on build-stamp watermark (short git commit hash) drawn in
+ *              the lower-left corner, independent of the F3 debug overlay.
+ *
+ * @copyright   Copyright (c) 2026 Project Gracemeria
+ * @license     BSD 3-Clause License
+ */
+#pragma once
+#include <rex/ui/imgui_dialog.h>
+
+namespace rex::ui {
+
+// A non-interactive dialog that draws the build's short git commit hash in the
+// lower-left corner every frame. Registers itself with the ImGuiDrawer on
+// construction (like any ImGuiDialog). Drawing is gated by the show_build_stamp
+// cvar (on by default); set it false to hide the watermark.
+class BuildStampOverlay : public ImGuiDialog {
+ public:
+  explicit BuildStampOverlay(ImGuiDrawer* imgui_drawer);
+
+ protected:
+  void OnDraw(ImGuiIO& io) override;
+};
+
+}  // namespace rex::ui

thirdparty/rexglue-sdk/include/rex/version.h.in

@@ -8,6 +8,7 @@
 
 #define REXGLUE_BUILD_PLATFORM "@REX_PLATFORM@"
 #define REXGLUE_BUILD_TIMESTAMP "@REXGLUE_BUILD_TIMESTAMP@"
+#define REXGLUE_GIT_HASH "@REXGLUE_GIT_HASH@"
 
 // Requires REXGLUE_BUILD_CONFIG compile definition
 // Title: "[rexglue-v0.7.1-Release]"
@@ -18,3 +19,7 @@
 #define REXGLUE_BUILD_STAMP \
   "build: rexglue-v" REXGLUE_VERSION_STRING "-" REXGLUE_BUILD_PLATFORM \
   "-" REXGLUE_BUILD_CONFIG "@" REXGLUE_BUILD_TIMESTAMP
+
+// Watermark: "rexglue-v0.7.1-Release @5120188b" (short git commit hash)
+#define REXGLUE_BUILD_HASH_STAMP \
+  "rexglue-v" REXGLUE_VERSION_STRING "-" REXGLUE_BUILD_CONFIG " @" REXGLUE_GIT_HASH

thirdparty/rexglue-sdk/src/native/ui/CMakeLists.txt

@@ -17,6 +17,7 @@ set(REXUI_CORE_SOURCES
 
 set(REXUI_OVERLAY_SOURCES
     ${REXGLUE_ROOT}/src/ui/overlay/debug_overlay.cpp
+    ${REXGLUE_ROOT}/src/ui/overlay/build_stamp_overlay.cpp
     ${REXGLUE_ROOT}/src/ui/overlay/console_overlay.cpp
     ${REXGLUE_ROOT}/src/ui/overlay/settings_overlay.cpp
 )

thirdparty/rexglue-sdk/src/native/ui/rex_app.cpp

@@ -223,6 +223,7 @@ bool ReXApp::OnInitialize() {
         imgui_drawer_->SetPresenterAndImmediateDrawer(presenter, immediate_drawer_.get());
         // Built-in overlays
         debug_overlay_ = std::make_unique<ui::DebugOverlayDialog>(imgui_drawer_.get());
+        build_stamp_overlay_ = std::make_unique<ui::BuildStampOverlay>(imgui_drawer_.get());
         console_overlay_ = std::make_unique<ui::ConsoleDialog>(imgui_drawer_.get(), log_sink_);
         settings_overlay_ = std::make_unique<ui::SettingsDialog>(
             imgui_drawer_.get(), config_path);
@@ -309,6 +310,7 @@ void ReXApp::OnDestroy() {
   // ImGui cleanup (reverse of setup)
   settings_overlay_.reset();
   console_overlay_.reset();
+  build_stamp_overlay_.reset();
   debug_overlay_.reset();
   if (imgui_drawer_) {
     imgui_drawer_->SetPresenterAndImmediateDrawer(nullptr, nullptr);

thirdparty/rexglue-sdk/src/ui/CMakeLists.txt

@@ -19,6 +19,7 @@ set(REXUI_CORE_SOURCES
 # Optional overlay dialogs
 set(REXUI_OVERLAY_SOURCES
     overlay/debug_overlay.cpp
+    overlay/build_stamp_overlay.cpp
     overlay/console_overlay.cpp
     overlay/settings_overlay.cpp
 )

thirdparty/rexglue-sdk/src/ui/overlay/build_stamp_overlay.cpp

@@ -0,0 +1,40 @@
+/**
+ * @file        ui/overlay/build_stamp_overlay.cpp
+ * @brief       Always-on build-stamp watermark. See build_stamp_overlay.h.
+ *
+ * @copyright   Copyright (c) 2026 Project Gracemeria
+ * @license     BSD 3-Clause License
+ */
+#include <rex/ui/overlay/build_stamp_overlay.h>
+#include <rex/cvar.h>
+#include <rex/version.h>
+#include <imgui.h>
+
+REXCVAR_DEFINE_BOOL(show_build_stamp, true, "UI",
+                    "Draw the build-stamp watermark (short git commit hash) in the "
+                    "lower-left corner. On by default; set false to hide it.");
+
+namespace rex::ui {
+
+BuildStampOverlay::BuildStampOverlay(ImGuiDrawer* imgui_drawer) : ImGuiDialog(imgui_drawer) {}
+
+void BuildStampOverlay::OnDraw(ImGuiIO& io) {
+  if (!REXCVAR_GET(show_build_stamp))
+    return;
+
+  const float margin = io.DisplaySize.y * 0.02f;
+  const ImVec2 size = ImGui::CalcTextSize(REXGLUE_BUILD_HASH_STAMP);
+  ImGui::SetNextWindowPos(ImVec2(margin, io.DisplaySize.y - size.y - margin));
+  ImGui::SetNextWindowSize(ImVec2(0, 0));
+  ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(1.0f, 1.0f, 1.0f, 0.5f));
+  if (ImGui::Begin("##buildstamp", nullptr,
+                   ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoBackground |
+                       ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoNav |
+                       ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_AlwaysAutoResize)) {
+    ImGui::TextUnformatted(REXGLUE_BUILD_HASH_STAMP);
+  }
+  ImGui::End();
+  ImGui::PopStyleColor();
+}
+
+}  // namespace rex::ui