From 0127fcfc73048ad7f446096007e8820e1cad8328 Mon Sep 17 00:00:00 2001
From: yacineolivier-maker
 <234833416+yacineolivier-maker@users.noreply.github.com>
Date: Tue, 20 Oct 2026 21:58:39 +0200
Subject: [PATCH] Host HUD layer: psx_host_set_hud_draw_cb, drawn under the
 in-game menu

A title can draw its own heads-up display on the host side (ImGui, like the
in-game overlay provider), once per presented frame -- real and generated
frames -- under the in-game menu and with the same thread and GL rules as
psx_host_overlay_set_draw_cb. Registered once at title activation; NULL
unregisters. No callback registered: no change in behaviour.

Used by a modern race HUD for R4 (lap, timing, tachometer, track map) drawn
at window resolution instead of the 320x240 native one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rkyma8rbyPiccs9n2bkyG6
---
 runtime/include/host_overlay.h |  8 ++++++++
 runtime/src/gpu_gl_renderer.c  |  6 ++++--
 runtime/src/host_overlay.c     | 14 ++++++++++++++
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/runtime/include/host_overlay.h b/runtime/include/host_overlay.h
index 06c2e504..d1bfcf3f 100644
--- a/runtime/include/host_overlay.h
+++ b/runtime/include/host_overlay.h
@@ -46,6 +46,14 @@ void psx_host_overlay_set_draw_cb(PsxHostOverlayDrawFn fn, void *ctx);
 int  psx_host_overlay_has_draw(void);
 void psx_host_overlay_draw(int width, int height);  /* renderer side */
 
+/* ---- Game HUD layer ---------------------------------------------------------
+ * A title's own heads-up display, drawn once per presented frame (real and
+ * generated) under the in-game menu, same thread and GL rules as the overlay
+ * callback above. Set once (title activation) and kept for the session; NULL
+ * unregisters (no wait: the registrant keeps fn and ctx alive for the session). */
+void psx_host_set_hud_draw_cb(PsxHostOverlayDrawFn fn, void *ctx);
+void psx_host_hud_draw(int width, int height);  /* renderer side */
+
 /* ---- P3: input sink -----------------------------------------------------
  * The sink sees every host SDL event first (main thread), in the normal event
  * drain and in the host pause loop. Returning non-zero consumes the event.
diff --git a/runtime/src/gpu_gl_renderer.c b/runtime/src/gpu_gl_renderer.c
index dab81837..67b2f4a0 100644
--- a/runtime/src/gpu_gl_renderer.c
+++ b/runtime/src/gpu_gl_renderer.c
@@ -9908,8 +9908,10 @@ static void gl_swap_with_osd(void) {
             }
             if (ov_image(3, &px, &ow, &oh) && px)
                 gl_draw_osd_image(px, ow, oh, ww, wh, 0, 0, ww, wh);
-            /* In-game overlay provider (host_overlay.h P2), over everything
-             * the host composes; no-op unless one registered. */
+            /* The title's HUD layer, then the in-game overlay provider
+             * (host_overlay.h P2) over everything; each a no-op unless one
+             * registered. */
+            psx_host_hud_draw(ww, wh);
             psx_host_overlay_draw(ww, wh);
         }
     }
diff --git a/runtime/src/host_overlay.c b/runtime/src/host_overlay.c
index 100f7a97..dfc7536c 100644
--- a/runtime/src/host_overlay.c
+++ b/runtime/src/host_overlay.c
@@ -101,6 +101,20 @@ void psx_host_overlay_draw(int width, int height) {
     atomic_fetch_sub(&s_draw_inflight, 1);
 }
 
+/* ---- Game HUD layer ------------------------------------------------------- */
+static PsxHostOverlayDrawFn s_hud_fn = NULL;
+static void *s_hud_ctx = NULL;
+
+void psx_host_set_hud_draw_cb(PsxHostOverlayDrawFn fn, void *ctx) {
+    s_hud_ctx = ctx;
+    s_hud_fn = fn;
+}
+
+void psx_host_hud_draw(int width, int height) {
+    PsxHostOverlayDrawFn fn = s_hud_fn;
+    if (fn && width > 0 && height > 0) fn(width, height, s_hud_ctx);
+}
+
 /* ---- P3: input sink -------------------------------------------------------- */
 static PsxHostInputSinkFn s_sink_fn = NULL;
 static void *s_sink_ctx = NULL;