World: add skybox changer

New Visuals -> Skybox card with a runtime sv_skyname override using the same
mechanism as the stock skybox_swapper entity. The choice list is the HL2
skybox set extracted from the game VPKs.

The map's own sky is captured from loaded materials (SkyBox group, parsing
skybox/<name>... face names) before the first override, so turning the
feature off or picking "Map default" restores it; a level change restores it
implicitly. Sky changes invalidate the world tint so new sky materials are
tinted as well.

GUI: add a CK_CHOICE control (value box with < / > zones).

5 files changed, 244 insertions, 7 deletions

diff --git a/src/gui.cpp b/src/gui.cpp
index aa47868..5fb8fa7 100644
--- a/src/gui.cpp
+++ b/src/gui.cpp
@@ -183,7 +183,8 @@ enum CtrlKind {
   CK_SECTION,
   CK_INFO,
   CK_BUTTON,
-  CK_COLOR
+  CK_COLOR,
+  CK_CHOICE
 };
 
 enum CtrlAction { ACT_NONE = 0, ACT_RELOAD, ACT_RESET };
@@ -195,6 +196,8 @@ struct Ctrl {
   bool *bval; // CK_TOGGLE
   int *ival;  // CK_SLIDER
   int *rgb;   // CK_COLOR: three ints, 0..255
+  const char *const *opts; // CK_CHOICE: option labels
+  int nopts;
   int min, max;
   int action; // CK_BUTTON
   bool zero_unlimited; // slider: value 0 displays as "All"
@@ -253,6 +256,8 @@ static void add_ctrl(int card, int kind, const char *label, const char *desc,
   c.action = action;
   c.zero_unlimited = false;
   c.rgb = nullptr;
+  c.opts = nullptr;
+  c.nopts = 0;
   c.hue = 0.0f;
   c.sat = 0.0f;
   c.val = 1.0f;
@@ -282,11 +287,19 @@ static void add_color(int card, const char *label, const char *desc,
   add_ctrl(card, CK_COLOR, label, desc, 0, 255, nullptr, nullptr, ACT_NONE);
   g_ctrls[i].rgb = rgb;
 }
+static void add_choice(int card, const char *label, const char *desc,
+                       const char *const *opts, int nopts, int *value) {
+  int i = g_nctrl;
+  add_ctrl(card, CK_CHOICE, label, desc, 0, nopts > 0 ? nopts - 1 : 0,
+           nullptr, value, ACT_NONE);
+  g_ctrls[i].opts = opts;
+  g_ctrls[i].nopts = nopts;
+}
 
 static int ctrl_val(const Ctrl &c) {
   if (c.kind == CK_TOGGLE && c.bval)
     return *c.bval ? 1 : 0;
-  if (c.kind == CK_SLIDER && c.ival)
+  if ((c.kind == CK_SLIDER || c.kind == CK_CHOICE) && c.ival)
     return *c.ival;
   return 0;
 }
@@ -294,7 +307,7 @@ static void ctrl_set(Ctrl &c, int v) {
   if (c.kind == CK_TOGGLE && c.bval) {
     *c.bval = v != 0;
     config_save();
-  } else if (c.kind == CK_SLIDER && c.ival) {
+  } else if ((c.kind == CK_SLIDER || c.kind == CK_CHOICE) && c.ival) {
     if (v < c.min) v = c.min;
     if (v > c.max) v = c.max;
     if (*c.ival != v) {
@@ -420,6 +433,13 @@ static void build_cards() {
   add_toggle(fog, "Remove fog",
              "Disable fog entirely instead of recolouring it.", &g_fog_disable);
 
+  int sky = add_card(2, &g_skybox, "Skybox",
+                     "Swap the skybox at runtime through sv_skyname. The "
+                     "map's own sky comes back on level change.",
+                     true);
+  add_choice(sky, "Sky", "Pick a skybox from the HL2 set.", skybox_options(),
+             skybox_option_count(), &g_skybox_choice);
+
   int spread = add_card(3, &g_spread, "Spread control",
                         "Choose a server shot seed that tightens the cone.",
                         true);
@@ -835,6 +855,8 @@ static int header_h(const Card &c) {
 static int label_max_w(const Ctrl &c) {
   if (c.kind == CK_SLIDER)
     return S(214.0f);
+  if (c.kind == CK_CHOICE)
+    return card_content_w() - S(16.0f) - S(250.0f);
   return card_content_w() - S(16.0f) - S(110.0f);
 }
 
@@ -1409,6 +1431,25 @@ static void handle_mouse_click() {
           }
           return;
         }
+        if (ct.kind == CK_CHOICE) {
+          int base = label_row_h(ct);
+          Rect box{cr.x + cr.w - S(238.0f),
+                   by + (base - S(24.0f)) / 2, S(222.0f), S(24.0f)};
+          if (box.has(mx, my)) {
+            int v = ctrl_val(ct);
+            if (mx < box.x + S(36.0f))
+              v--;
+            else if (mx >= box.x + box.w - S(36.0f))
+              v++;
+            if (v < 0) v = 0;
+            if (ct.nopts > 0 && v >= ct.nopts) v = ct.nopts - 1;
+            if (v != ctrl_val(ct)) {
+              *ct.ival = v;
+              config_save();
+            }
+          }
+          return;
+        }
         if (ct.kind == CK_BUTTON) {
           int bw = button_w(ct.label);
           Rect b{cr.x + cr.w - S(16.0f) - bw,
@@ -1799,6 +1840,25 @@ static void draw_card(const Rect &clip, int index, int y) {
         outline(sw, picker_open_for(ct) ? C_ACCENT : C_BORDER, &clip);
         if (picker_open_for(ct))
           draw_picker(clip, cr, ct, by);
+      } else if (ct.kind == CK_CHOICE) {
+        int v = ctrl_val(ct);
+        const char *name = (ct.opts && v >= 0 && v < ct.nopts)
+                               ? ct.opts[v]
+                               : "?";
+        Rect box{cr.x + cr.w - S(238.0f),
+                 by + (base_h - S(24.0f)) / 2, S(222.0f), S(24.0f)};
+        fill(box, Col{45, 50, 60, 255}, &clip);
+        outline(box, C_BORDER, &clip);
+        int ty = box.y + (box.h - g_body_h) / 2;
+        text_in(clip, box.x + S(8.0f), ty, "<", g_font_body, g_body_h, 0,
+                C_DIM);
+        text_in(clip, box.x + box.w - S(16.0f), ty, ">", g_font_body, g_body_h,
+                0, C_DIM);
+        int w = text_w(name, g_body_h);
+        int tx = box.x + (box.w - w) / 2;
+        if (tx < box.x + S(24.0f))
+          tx = box.x + S(24.0f);
+        text_in(clip, tx, ty, name, g_font_body, g_body_h, 0, C_TEXT);
       }
     }
     by += rh;
diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index 3f1acb4..4ba1af3 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -592,6 +592,7 @@ static void do_move(int seq, float frametime) {
     fullbright_invalidate();
     world_tint_invalidate();
     fog_invalidate();
+    skybox_invalidate();
   }
 
   if (feature_active(FEAT_SPREAD)) {
diff --git a/src/hl2h.h b/src/hl2h.h
index 877afac..3cb131d 100644
--- a/src/hl2h.h
+++ b/src/hl2h.h
@@ -180,7 +180,8 @@ enum FeatureId {
   FEAT_FULLBRIGHT = 10,
   FEAT_WORLD_TINT = 11,
   FEAT_FOG = 12,
-  FEAT_COUNT = 13
+  FEAT_SKYBOX = 13,
+  FEAT_COUNT = 14
 };
 enum EspOption {
   ESP_OPT_SHOW_NEUTRAL = 0,
@@ -213,11 +214,15 @@ struct FeatureState {
 
 extern FeatureState g_bhop, g_abh, g_jumpbug, g_melee, g_spread, g_esp,
     g_aimbot, g_triggerbot, g_silentaim, g_item_esp, g_fullbright,
-    g_world_tint, g_fog;
+    g_world_tint, g_fog, g_skybox;
 extern bool g_tint_world_on, g_tint_sky_on, g_tint_prop_on;
 extern int g_tint_world_rgb[3], g_tint_sky_rgb[3], g_tint_prop_rgb[3];
 extern bool g_fog_skybox, g_fog_disable;
 extern int g_fog_rgb[3], g_fog_start, g_fog_end;
+extern int g_skybox_choice;
+int skybox_option_count();
+const char *skybox_option_name(int i);
+const char *const *skybox_options();
 extern bool g_bhop_autostrafe;
 extern bool g_jumpbug_assist;
 extern bool g_spread_no_spread;
@@ -260,6 +265,8 @@ void world_tint_update();
 void world_tint_invalidate();
 void fog_update();
 void fog_invalidate();
+void skybox_update();
+void skybox_invalidate();
 bool resolve_server_netvars();
 int server_entity_health(int idx, int *maxhealth, int *lifestate, void **base_out);
 bool server_set_velocity_z(int idx, float vz);
diff --git a/src/menu.cpp b/src/menu.cpp
index 237502b..dfd973d 100644
--- a/src/menu.cpp
+++ b/src/menu.cpp
@@ -59,6 +59,8 @@ bool g_fog_disable = false;
 int g_fog_rgb[3] = {160, 170, 190};
 int g_fog_start = 200;
 int g_fog_end = 3000;
+FeatureState g_skybox{false, 0}; // sv_skyname override
+int g_skybox_choice = 0;         // 0 = map default
 bool g_item_health = true;
 bool g_item_ammo = true;
 bool g_item_armor = true;
@@ -212,6 +214,8 @@ void config_save() {
              "start=%d\nend=%d\nskybox=%d\ndisable=%d\n",
           g_fog.active, g_fog.bind, g_fog_rgb[0], g_fog_rgb[1], g_fog_rgb[2],
           g_fog_start, g_fog_end, (int)g_fog_skybox, (int)g_fog_disable);
+  fprintf(f, "[skybox]\nactive=%d\nbind=%d\nchoice=%d\n", g_skybox.active,
+          g_skybox.bind, g_skybox_choice);
   fprintf(f, "[items]\nactive=%d\nbind=%d\nhealth=%d\nammo=%d\n"
              "armor=%d\nweapons=%d\ncrates=%d\ndistance=%d\nmax_dist=%d\n",
           g_item_esp.active, g_item_esp.bind, (int)g_item_health,
@@ -246,7 +250,7 @@ static bool config_load() {
   FeatureState *cur = nullptr;
   bool in_esp = false, in_bhop = false, in_aim = false, in_silent = false,
        in_jumpbug = false, in_spread = false, in_items = false,
-       in_tint = false, in_fog = false;
+       in_tint = false, in_fog = false, in_skybox = false;
   while (fgets(line, sizeof(line), f)) {
     line[strcspn(line, "\r\n")] = 0;
     if (line[0] == '[') {
@@ -270,6 +274,8 @@ static bool config_load() {
         cur = &g_world_tint;
       else if (strstr(line, "[fog]"))
         cur = &g_fog;
+      else if (strstr(line, "[skybox]"))
+        cur = &g_skybox;
       else if (strstr(line, "[aimbot]"))
         cur = &g_aimbot;
       else if (strstr(line, "[triggerbot]"))
@@ -287,6 +293,7 @@ static bool config_load() {
       in_items = (cur == &g_item_esp);
       in_tint = (cur == &g_world_tint);
       in_fog = (cur == &g_fog);
+      in_skybox = (cur == &g_skybox);
     } else if (cur) {
       char *eq = strchr(line, '=');
       if (!eq)
@@ -407,6 +414,12 @@ static bool config_load() {
           g_fog_disable = atoi(val) != 0;
         }
       }
+      if (in_skybox && strcmp(key, "choice") == 0) {
+        int v = atoi(val);
+        if (v < 0) v = 0;
+        if (v >= skybox_option_count()) v = 0;
+        g_skybox_choice = v;
+      }
       if (in_esp) {
         if (strcmp(key, "neutral") == 0)
           g_esp_opt[ESP_OPT_SHOW_NEUTRAL] = atoi(val) != 0;
@@ -475,6 +488,8 @@ void config_reset_defaults() {
   g_fog_rgb[2] = 190;
   g_fog_start = 200;
   g_fog_end = 3000;
+  g_skybox = {false, 0};
+  g_skybox_choice = 0;
   g_item_health = true;
   g_item_ammo = true;
   g_item_armor = true;
@@ -592,7 +607,7 @@ static FeatureState *feature_state(int feature) {
   static FeatureState *feats[FEAT_COUNT] = {
       &g_bhop,    &g_abh,        &g_esp,        &g_aimbot, &g_triggerbot,
       &g_silentaim, &g_jumpbug,  &g_melee,      &g_spread, &g_item_esp,
-      &g_fullbright, &g_world_tint, &g_fog};
+      &g_fullbright, &g_world_tint, &g_fog, &g_skybox};
   if (feature < 0 || feature >= FEAT_COUNT)
     return nullptr;
   return feats[feature];
@@ -800,6 +815,7 @@ void outer_draw() {
   fullbright_update();
   world_tint_update();
   fog_update();
+  skybox_update();
   gui_handle_input();
   // HL2H_DRAW_TEST=1 draws a probe rect without needing the GUI open
   static bool draw_test = getenv("HL2H_DRAW_TEST") != nullptr;
@@ -822,6 +838,7 @@ void outer_draw() {
       font_reset = true;
       world_tint_invalidate();
       fog_invalidate();
+      skybox_invalidate();
     }
   }
   if (font_reset && g_font) {
diff --git a/src/world.cpp b/src/world.cpp
index 2333829..73738db 100644
--- a/src/world.cpp
+++ b/src/world.cpp
@@ -340,3 +340,155 @@ void fog_update() {
   logf("fog: %s colour=(%d,%d,%d) start=%d end=%d skybox=%d", disable ? "off"
        : "on", r, g, b, start, end, (int)skybox);
 }
+
+// ---------------------------------------------------------------------------
+// Skybox changer (sv_skyname; same mechanism as the skybox_swapper entity)
+// ---------------------------------------------------------------------------
+
+namespace {
+
+// HL2's skybox set. Index 0 means "do not force a sky"; the rest are the
+// base names the engine expands to skybox/<name>{rt,bk,lf,ft,up,dn}.
+const char *const kSkyboxLabels[] = {
+    "Map default",     "sky_day01_01", "sky_day01_04", "sky_day01_05",
+    "sky_day01_06",    "sky_day01_07", "sky_day01_08", "sky_day01_09",
+    "sky_day02_01",    "sky_day02_02", "sky_day02_03", "sky_day02_04",
+    "sky_day02_05",    "sky_day02_06", "sky_day02_07", "sky_day02_09",
+    "sky_day02_10",    "sky_day03_01", "sky_day03_02", "sky_day03_03",
+    "sky_day03_04",    "sky_day03_05", "sky_day03_06", "sky_day03_06b",
+    "sky_day03_06c",   "sky_wasteland02", "sky_borealis01", "sky_fog_002",
+    "sky_fake_white"};
+
+std::string g_sky_original;      // map's own sky, captured before overriding
+bool g_sky_original_valid = false;
+std::string g_sky_active;        // value we forced, empty when not forcing
+
+// "skybox/sky_day01_01_hdrrt" -> "sky_day01_01"
+bool parse_sky_material(const char *mat, char *out, size_t outn) {
+  if (!mat)
+    return false;
+  const char *n = mat;
+  if (strncmp(n, "skybox/", 7) == 0)
+    n += 7;
+  size_t len = strlen(n);
+  if (len < 4)
+    return false;
+  static const char *faces[] = {"rt", "bk", "lf", "ft", "up", "dn", nullptr};
+  const char *suf = n + len - 2;
+  bool face = false;
+  for (int i = 0; faces[i]; i++) {
+    if (strcmp(suf, faces[i]) == 0) {
+      face = true;
+      break;
+    }
+  }
+  if (!face)
+    return false;
+  size_t blen = len - 2;
+  if (blen > 4 && (strncmp(n + blen - 4, "_hdr", 4) == 0 ||
+                   strncmp(n + blen - 4, "_ldr", 4) == 0))
+    blen -= 4;
+  if (blen == 0 || blen >= outn)
+    return false;
+  memcpy(out, n, blen);
+  out[blen] = 0;
+  return true;
+}
+
+void capture_map_sky() {
+  if (g_sky_original_valid)
+    return;
+  g_sky_original_valid = true; // one attempt per map, even on failure
+  void *ms = material_system();
+  if (!ms)
+    return;
+  auto invalid = vfunc<MatCalls::InvalidFn>(ms, MATSYS_InvalidMaterial);
+  auto first = vfunc<MatCalls::FirstFn>(ms, MATSYS_FirstMaterial);
+  auto next = vfunc<MatCalls::NextFn>(ms, MATSYS_NextMaterial);
+  auto get = vfunc<MatCalls::GetFn>(ms, MATSYS_GetMaterial);
+  auto count = vfunc<MatCalls::CountFn>(ms, MATSYS_GetNumMaterials);
+  int total = count(ms);
+  if (total <= 0 || total > 200000)
+    return;
+  unsigned short inv = invalid(ms);
+  int seen = 0;
+  std::string last;
+  for (unsigned short h = first(ms); h != inv; h = next(ms, h)) {
+    if (++seen > total + 16)
+      break;
+    void *mat = get(ms, h);
+    if (!mat)
+      continue;
+    const char *name = vfunc<MatCalls::NameFn>(mat, MAT_GetName)(mat);
+    const char *group =
+        vfunc<MatCalls::GroupFn>(mat, MAT_GetTextureGroupName)(mat);
+    if (!plausible_name(name) || !plausible_name(group))
+      continue;
+    if (strncmp(group, GROUP_SKYBOX, strlen(GROUP_SKYBOX)) != 0)
+      continue;
+    char base[128];
+    if (parse_sky_material(name, base, sizeof(base)))
+      last = base; // newest loaded sky materials win after a level change
+  }
+  if (last.empty()) {
+    logd("skybox: could not capture the map sky");
+    return;
+  }
+  g_sky_original = last;
+  logf("skybox: map sky is %s", g_sky_original.c_str());
+}
+
+} // namespace
+
+int skybox_option_count() {
+  return (int)(sizeof(kSkyboxLabels) / sizeof(kSkyboxLabels[0]));
+}
+
+const char *skybox_option_name(int i) {
+  int n = skybox_option_count();
+  return (i >= 0 && i < n) ? kSkyboxLabels[i] : kSkyboxLabels[0];
+}
+
+const char *const *skybox_options() { return kSkyboxLabels; }
+
+void skybox_invalidate() {
+  // Level change: the engine sets sv_skyname from worldspawn again, so there is
+  // nothing to restore. Forget the captured base and let it recapture.
+  g_sky_original.clear();
+  g_sky_original_valid = false;
+  g_sky_active.clear();
+}
+
+void skybox_update() {
+  bool on = feature_active(FEAT_SKYBOX);
+  int choice = g_skybox_choice;
+  int n = skybox_option_count();
+  if (choice < 0 || choice >= n)
+    choice = 0;
+
+  if (!on || choice == 0) {
+    if (g_sky_active.empty())
+      return;
+    if (g_sky_original_valid && !g_sky_original.empty() &&
+        g_sky_original != g_sky_active) {
+      char cmd[160];
+      snprintf(cmd, sizeof(cmd), "sv_skyname %s", g_sky_original.c_str());
+      console_cmd(cmd);
+      logf("skybox: restored %s", g_sky_original.c_str());
+      world_tint_invalidate(); // the new sky materials need the sky tint
+    }
+    g_sky_active.clear();
+    return;
+  }
+
+  capture_map_sky(); // before the first override of this map
+  const char *want = skybox_option_name(choice);
+  if (g_sky_active == want)
+    return;
+  char cmd[160];
+  snprintf(cmd, sizeof(cmd), "sv_skyname %s", want);
+  console_cmd(cmd);
+  logf("skybox: %s", want);
+  g_sky_active = want;
+  world_tint_invalidate(); // tint materials for the freshly loaded sky
+}