Add HDR tonemap brightness slider

The engine applies mat_monitorgamma (SDL receives changing ramp midpoints),
but Wayland/XWayland compositors discard the window gamma ramp, so the gamma
slider has no visible effect there. Add an in-engine brightness control that
does not depend on the window system: mat_force_tonemap_scale, exposed as
"HDR brightness" (x10, 0 = automatic). Drop the temporary SDL gamma ramp
diagnostic.

5 files changed, 52 insertions, 17 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index fc73214..e0af84a 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -241,14 +241,15 @@ vocabulary / decisions.
   `ClientCmd` when their slider changes. Gamma is stored as x10
   (`[view] gamma=22` = 2.2) and the slider stops at 26 because the engine
   clamps `mat_monitorgamma` at 2.6. The value is read back through
-  `ICvar::FindVar` on the next tick (ClientCmd is queued) and logged
-  (`view: gamma request ..., cvar reports ...`) to distinguish a rejected
-  command from an OS gamma ramp the compositor ignores. `SDL_SetWindowGammaRamp`
-  is also interposed (first 12 calls log `gamma: SDL_SetWindowGammaRamp
-  mid=...`) to see whether the engine ever pushes a ramp after the slider
-  moves; if it does and the screen does not change, the compositor is
-  discarding it. Both live in the always-on
-  `Camera / display` card (`[view] fov/vmfov/gamma`).
+  `ICvar::FindVar` on the next tick (ClientCmd is queued) and logged. The
+  engine does apply the ramp (`SDL_SetWindowGammaRamp` was called with
+  changing midpoints), but a Wayland/XWayland compositor discards it, so on
+  this setup the slider has no visible effect.
+- `HDR brightness` (`[view] tonemap`, x10, 0 = automatic) sets
+  `mat_force_tonemap_scale`. This is in-engine tonemapping for HDR maps and
+  does not depend on the window system applying a gamma ramp; 10 = 1.0.
+  Both live in the always-on `Camera / display` card
+  (`[view] fov/vmfov/gamma/tonemap`).
 
 ## Map transitions
 
diff --git a/src/gui.cpp b/src/gui.cpp
index e8bcac7..83dc0a5 100644
--- a/src/gui.cpp
+++ b/src/gui.cpp
@@ -420,8 +420,12 @@ static void build_cards() {
              &g_fov_viewmodel);
   add_slider(view, "Gamma x10",
              "mat_monitorgamma x10: 16 = 1.6, 26 = 2.6 (engine max), stock "
-             "is 22.",
+             "is 22. Uses the OS gamma ramp; some compositors ignore it.",
              16, 26, &g_gamma);
+  add_slider(view, "HDR brightness",
+             "mat_force_tonemap_scale x10 (0 = automatic). In-engine "
+             "brightness for HDR maps; 10 = 1.0.",
+             0, 30, &g_tonemap);
 
   add_card(2, &g_fullbright, "Fullbright",
            "Ignore world lighting so dark areas are visible.", true);
@@ -2254,12 +2258,6 @@ SDL_SetWindowGammaRamp(void *window, const unsigned short *r,
                                    const unsigned short *,
                                    const unsigned short *))dlsym(
         RTLD_NEXT, "SDL_SetWindowGammaRamp");
-  static int logs = 0;
-  if (logs < 12) {
-    logs++;
-    logf("gamma: SDL_SetWindowGammaRamp mid=%u/%u/%u", r ? r[128] : 0,
-         g ? g[128] : 0, b ? b[128] : 0);
-  }
   return real_set_gamma_ramp ? real_set_gamma_ramp(window, r, g, b) : -1;
 }
 
diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index 1fc7096..a037bac 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -698,6 +698,34 @@ static void view_settings_apply(void *ent) {
          pending_gamma % 10, got);
     pending_gamma = -1;
   }
+  // In-engine brightness for HDR maps. Unlike mat_monitorgamma this does not
+  // depend on the window system applying a gamma ramp.
+  static int last_tonemap = 0;
+  static int pending_tonemap = -1;
+  if (g_tonemap != last_tonemap) {
+    char cmd[64];
+    if (g_tonemap == 0)
+      snprintf(cmd, sizeof(cmd), "mat_force_tonemap_scale 0");
+    else
+      snprintf(cmd, sizeof(cmd), "mat_force_tonemap_scale %d.%d",
+               g_tonemap / 10, g_tonemap % 10);
+    console_cmd(cmd);
+    pending_tonemap = g_tonemap;
+    last_tonemap = g_tonemap;
+  }
+  if (pending_tonemap >= 0) {
+    float got = -1.0f;
+    if (g_iface.cvar) {
+      using FindFn = void *(*)(void *, const char *);
+      void *v = vfunc<FindFn>(g_iface.cvar, 12)(g_iface.cvar,
+                                                "mat_force_tonemap_scale");
+      if (v)
+        got = *(float *)((uintptr_t)v + 0x2c);
+    }
+    logf("view: tonemap request %d.%d, cvar reports %.2f",
+         pending_tonemap / 10, pending_tonemap % 10, got);
+    pending_tonemap = -1;
+  }
 }
 
 // ---------------------------------------------------------------------------
diff --git a/src/hl2h.h b/src/hl2h.h
index 6b142c7..a050feb 100644
--- a/src/hl2h.h
+++ b/src/hl2h.h
@@ -249,6 +249,7 @@ extern bool g_edge_jump;
 extern int g_fov_camera;
 extern int g_fov_viewmodel;
 extern int g_gamma;
+extern int g_tonemap;
 extern int g_esp_col_hostile[3];
 extern int g_esp_col_neutral[3];
 extern int g_esp_col_friendly[3];
diff --git a/src/menu.cpp b/src/menu.cpp
index 248aa48..033c0f9 100644
--- a/src/menu.cpp
+++ b/src/menu.cpp
@@ -82,6 +82,7 @@ bool g_edge_jump = false;
 int g_fov_camera = 75;    // HL2's stock camera FOV
 int g_fov_viewmodel = 54; // HL2's stock viewmodel FOV
 int g_gamma = 22;       // mat_monitorgamma x10, stock 2.2
+int g_tonemap = 0;      // mat_force_tonemap_scale x10, 0 = automatic
 int g_esp_col_hostile[3] = {255, 60, 60};
 int g_esp_col_neutral[3] = {220, 220, 220};
 int g_esp_col_friendly[3] = {60, 255, 60};
@@ -248,8 +249,8 @@ void config_save() {
           g_esp_col_neutral[0], g_esp_col_neutral[1], g_esp_col_neutral[2],
           g_esp_col_friendly[0], g_esp_col_friendly[1],
           g_esp_col_friendly[2]);
-  fprintf(f, "[view]\nfov=%d\nvmfov=%d\ngamma=%d\n", g_fov_camera,
-          g_fov_viewmodel, g_gamma);
+  fprintf(f, "[view]\nfov=%d\nvmfov=%d\ngamma=%d\ntonemap=%d\n",
+          g_fov_camera, g_fov_viewmodel, g_gamma, g_tonemap);
   fprintf(f, "[movement]\ncrouchjump=%d\nedgejump=%d\n",
           (int)g_auto_crouchjump, (int)g_edge_jump);
   gui_config_write(f);
@@ -409,6 +410,11 @@ static bool config_load() {
           lo = 16;
           hi = 26; // the engine clamps mat_monitorgamma at 2.6
           stock = 22;
+        } else if (strcmp(key, "tonemap") == 0) {
+          dst = &g_tonemap;
+          lo = 0;
+          hi = 30;
+          stock = 0;
         }
         if (dst) {
           int v = atoi(val);
@@ -605,6 +611,7 @@ void config_reset_defaults() {
   g_fov_camera = 75;
   g_fov_viewmodel = 54;
   g_gamma = 22;
+  g_tonemap = 0;
   g_esp_col_hostile[0] = 255;
   g_esp_col_hostile[1] = 60;
   g_esp_col_hostile[2] = 60;