path: root/src/world.cpp

// world.cpp — world/sky material colour modulation.
//
// Same mechanism Amalgam uses for its "World modulation": walk every material
// in the material system and call IMaterial::ColorModulate on the ones whose
// texture group is the world (or the skybox). This multiplies the material's
// albedo; it does not touch lightmaps, so it is cheap and does not recompile
// shaders.
//
// HL2's materialsystem.so registers "VMaterialSystem080" (the SDK 2013 name
// for the modern layout) and exports CreateInterface, so the interface is
// obtained exactly like VClient017/VGUI_Surface030 elsewhere in this cheat.
//
// Vtable slots are taken from the 2013 SDK headers:
//   IMaterialSystem: FirstMaterial=73 NextMaterial=74 InvalidMaterial=75
//                    GetMaterial=76 GetNumMaterials=77
//   IMaterial:       GetName=0 GetTextureGroupName=1 ColorModulate=28

#include "hl2h.h"
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <dlfcn.h>

namespace {

constexpr int MATSYS_FirstMaterial = 73;
constexpr int MATSYS_NextMaterial = 74;
constexpr int MATSYS_InvalidMaterial = 75;
constexpr int MATSYS_GetMaterial = 76;
constexpr int MATSYS_GetNumMaterials = 77;

constexpr int MAT_GetName = 0;
constexpr int MAT_GetTextureGroupName = 1;
constexpr int MAT_ColorModulate = 28;

constexpr const char *GROUP_WORLD = "World textures";
constexpr const char *GROUP_SKYBOX = "SkyBox textures";

void *g_matsys = nullptr;
bool g_matsys_tried = false;
bool g_matsys_failed = false;
bool g_matsys_logged = false;

// Last state handed to the material system. Colour changes are applied when
// this differs from the desired state, so the all-material walk runs only on
// toggles/colour edits/level changes, never every frame.
struct Tint {
  bool valid;
  int world_r, world_g, world_b;
  int sky_r, sky_g, sky_b;
  int prop_r, prop_g, prop_b;
};
Tint g_applied{false, 255, 255, 255, 255, 255, 255, 255, 255, 255};

// Static props and prop_physics share their model materials; every stock HL2
// map prop lives under models/props*, which keeps NPC/player/weapon materials
// out of the prop pass.
bool is_prop_material(const char *name) {
  return name && strncmp(name, "models/props", 12) == 0;
}

struct MatCalls {
  using FirstFn = unsigned short (*)(void *);
  using NextFn = unsigned short (*)(void *, unsigned short);
  using InvalidFn = unsigned short (*)(void *);
  using GetFn = void *(*)(void *, unsigned short);
  using CountFn = int (*)(void *);
  using NameFn = const char *(*)(void *);
  using GroupFn = const char *(*)(void *);
  using ModulateFn = void (*)(void *, float, float, float);
};

// Reject obviously bogus strings returned by a mis-mapped vtable slot instead
// of walking thousands of materials with garbage pointers.
bool plausible_name(const char *s) {
  if (!s || !*s)
    return false;
  size_t n = strnlen(s, 512);
  if (n == 0 || n >= 512)
    return false;
  for (size_t i = 0; i < n; i++) {
    unsigned char c = (unsigned char)s[i];
    if (c < 0x20 || c == 0x7f)
      return false;
  }
  return true;
}

std::string find_loaded_module(const char *needle) {
  FILE *maps = fopen("/proc/self/maps", "r");
  if (!maps)
    return {};
  char line[1024];
  std::string found;
  while (fgets(line, sizeof(line), maps)) {
    char *p = strchr(line, '/');
    if (!p)
      continue;
    size_t pl = strlen(p);
    while (pl && (p[pl - 1] == '\n' || p[pl - 1] == '\r'))
      p[--pl] = 0;
    if (!strstr(p, needle) || !strstr(p, ".so"))
      continue;
    found = p;
    if (!strstr(p, "(deleted)"))
      break;
  }
  fclose(maps);
  return found;
}

void *material_system() {
  if (g_matsys_tried)
    return g_matsys;
  g_matsys_tried = true;

  std::string path = find_loaded_module("materialsystem");
  void *h = nullptr;
  if (!path.empty())
    h = dlopen(path.c_str(), RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
  // The engine always dlopens the module by name; NOLOAD only attaches to the
  // already-mapped copy, so we never spawn a second material system.
  if (!h)
    h = dlopen("materialsystem.so", RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
  if (!h) {
    g_matsys_failed = true;
    logf("tint: materialsystem.so not loaded");
    return nullptr;
  }
  auto cf = (CreateInterfaceFn)dlsym(h, "CreateInterface");
  if (!cf) {
    g_matsys_failed = true;
    logf("tint: materialsystem CreateInterface missing");
    return nullptr;
  }
  static const char *names[] = {"VMaterialSystem080", "VMaterialSystem082",
                                "VMaterialSystem081", nullptr};
  for (const char **n = names; *n; n++) {
    int ret = 0;
    void *ms = cf(*n, &ret);
    if (!ms)
      continue;
    g_matsys = ms;
    logf("tint: %s = %p via %s", *n, ms,
         path.empty() ? "materialsystem.so" : path.c_str());
    return ms;
  }
  g_matsys_failed = true;
  logf("tint: material system interface not exposed");
  return nullptr;
}

// Push one colour pair over all materials. Groups that are off get white so a
// previously tinted world is restored.
bool apply_tint(int world_r, int world_g, int world_b, int sky_r, int sky_g,
                int sky_b, int prop_r, int prop_g, int prop_b) {
  void *ms = material_system();
  if (!ms)
    return false;

  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) {
    logf("tint: GetNumMaterials() = %d (unexpected; disabled)", total);
    g_matsys_failed = true;
    toastf(TOAST_ERROR, "World tint: material system layout mismatch");
    return false;
  }

  float wr = world_r / 255.0f, wg = world_g / 255.0f, wb = world_b / 255.0f;
  float sr = sky_r / 255.0f, sg = sky_g / 255.0f, sb = sky_b / 255.0f;
  float pr = prop_r / 255.0f, pg = prop_g / 255.0f, pb = prop_b / 255.0f;

  unsigned short inv = invalid(ms);
  int seen = 0, world_hits = 0, sky_hits = 0, prop_hits = 0;
  for (unsigned short h = first(ms); h != inv; h = next(ms, h)) {
    if (++seen > total + 16) {
      logf("tint: material walk runaway (%d > %d); stopped", seen, total);
      break;
    }
    void *mat = get(ms, h);
    if (!mat)
      continue;
    auto name_fn = vfunc<MatCalls::NameFn>(mat, MAT_GetName);
    auto group_fn = vfunc<MatCalls::GroupFn>(mat, MAT_GetTextureGroupName);
    auto mod_fn = vfunc<MatCalls::ModulateFn>(mat, MAT_ColorModulate);
    const char *name = name_fn(mat);
    const char *group = group_fn(mat);
    if (!plausible_name(name) || !plausible_name(group))
      continue;
    // The first material's name also validates the IMaterial vtable mapping
    // before we poke any colour state.
    if (!g_matsys_logged) {
      g_matsys_logged = true;
      logf("tint: first material \"%s\" group \"%s\"", name, group);
    }
    bool is_world = strncmp(group, GROUP_WORLD, strlen(GROUP_WORLD)) == 0;
    bool is_sky = strncmp(group, GROUP_SKYBOX, strlen(GROUP_SKYBOX)) == 0 ||
                  strstr(name, "sky") != nullptr;
    if (is_world && !strstr(name, "sky")) {
      mod_fn(mat, wr, wg, wb);
      world_hits++;
    } else if (is_sky) {
      mod_fn(mat, sr, sg, sb);
      sky_hits++;
    } else if (is_prop_material(name)) {
      mod_fn(mat, pr, pg, pb);
      prop_hits++;
    }
  }
  logf("tint: applied world=%d(%d,%d,%d) sky=%d(%d,%d,%d) props=%d(%d,%d,%d) "
       "of %d materials",
       world_hits, world_r, world_g, world_b, sky_hits, sky_r, sky_g, sky_b,
       prop_hits, prop_r, prop_g, prop_b, total);
  return true;
}

} // namespace

void world_tint_invalidate() { g_applied.valid = false; }

void world_tint_update() {
  bool on = feature_active(FEAT_WORLD_TINT);
  bool world_on = on && g_tint_world_on;
  bool sky_on = on && g_tint_sky_on;
  bool prop_on = on && g_tint_prop_on;

  int wr = world_on ? g_tint_world_rgb[0] : 255;
  int wg = world_on ? g_tint_world_rgb[1] : 255;
  int wb = world_on ? g_tint_world_rgb[2] : 255;
  int sr = sky_on ? g_tint_sky_rgb[0] : 255;
  int sg = sky_on ? g_tint_sky_rgb[1] : 255;
  int sb = sky_on ? g_tint_sky_rgb[2] : 255;
  int pr = prop_on ? g_tint_prop_rgb[0] : 255;
  int pg = prop_on ? g_tint_prop_rgb[1] : 255;
  int pb = prop_on ? g_tint_prop_rgb[2] : 255;

  bool white = wr == 255 && wg == 255 && wb == 255 && sr == 255 &&
               sg == 255 && sb == 255 && pr == 255 && pg == 255 && pb == 255;
  if (g_applied.valid && g_applied.world_r == wr && g_applied.world_g == wg &&
      g_applied.world_b == wb && g_applied.sky_r == sr &&
      g_applied.sky_g == sg && g_applied.sky_b == sb &&
      g_applied.prop_r == pr && g_applied.prop_g == pg &&
      g_applied.prop_b == pb)
    return;
  // Nothing was ever tinted and nothing is requested: no need to walk the
  // material list just to write white over white.
  if (!g_applied.valid && white) {
    g_applied = {true, wr, wg, wb, sr, sg, sb, pr, pg, pb};
    return;
  }
  if (g_matsys_failed && !world_on && !sky_on && !prop_on) {
    g_applied = {true, wr, wg, wb, sr, sg, sb, pr, pg, pb};
    return;
  }
  if (!apply_tint(wr, wg, wb, sr, sg, sb, pr, pg, pb)) {
    if (g_matsys_failed)
      g_applied = {true, wr, wg, wb, sr, sg, sb, pr, pg, pb};
    return;
  }
  g_applied = {true, wr, wg, wb, sr, sg, sb, pr, pg, pb};
}

// ---------------------------------------------------------------------------
// Fog override (engine console commands; no render hooks)
// ---------------------------------------------------------------------------

namespace {

struct FogState {
  bool valid;
  bool on;
  bool disable;
  int r, g, b;
  int start, end;
  bool skybox;
};
FogState g_fog_applied{false, false, false, 0, 0, 0, 0, 0, false};

} // namespace

void fog_invalidate() { g_fog_applied.valid = false; }

void fog_update() {
  bool on = feature_active(FEAT_FOG);
  bool disable = on && g_fog_disable;
  int r = g_fog_rgb[0], g = g_fog_rgb[1], b = g_fog_rgb[2];
  int start = g_fog_start;
  int end = g_fog_end;
  if (end <= start)
    end = start + 1;
  bool skybox = on && g_fog_skybox;

  if (g_fog_applied.valid && g_fog_applied.on == on &&
      g_fog_applied.disable == disable && g_fog_applied.r == r &&
      g_fog_applied.g == g && g_fog_applied.b == b &&
      g_fog_applied.start == start && g_fog_applied.end == end &&
      g_fog_applied.skybox == skybox)
    return;

  if (!on) {
    if (g_fog_applied.valid && g_fog_applied.on)
      console_cmd("fog_override 0");
    g_fog_applied = {true, false, false, 0, 0, 0, 0, 0, false};
    return;
  }

  console_cmd("fog_override 1");
  char cmd[128];
  if (disable) {
    console_cmd("fog_enable 0");
    if (skybox)
      console_cmd("fog_enableskybox 0");
  } else {
    console_cmd("fog_enable 1");
    snprintf(cmd, sizeof(cmd), "fog_color %d %d %d", r, g, b);
    console_cmd(cmd);
    snprintf(cmd, sizeof(cmd), "fog_start %d", start);
    console_cmd(cmd);
    snprintf(cmd, sizeof(cmd), "fog_end %d", end);
    console_cmd(cmd);
    if (skybox) {
      console_cmd("fog_enableskybox 1");
      snprintf(cmd, sizeof(cmd), "fog_colorskybox %d %d %d", r, g, b);
      console_cmd(cmd);
      snprintf(cmd, sizeof(cmd), "fog_startskybox %d", start);
      console_cmd(cmd);
      snprintf(cmd, sizeof(cmd), "fog_endskybox %d", end);
      console_cmd(cmd);
    } else {
      console_cmd("fog_enableskybox 0");
    }
  }
  g_fog_applied = {true, on, disable, r, g, b, start, end, skybox};
  logf("fog: %s colour=(%d,%d,%d) start=%d end=%d skybox=%d", disable ? "off"
       : "on", r, g, b, start, end, (int)skybox);
}

// ---------------------------------------------------------------------------
// Skybox image (skybox.png from the config directory)
// ---------------------------------------------------------------------------

namespace {

struct PngImage {
  void *opaque;
  uint32_t version, width, height, format, flags, colormap_entries,
      warning_or_error;
  char message[64];
};

bool load_png_rgba(const char *path, std::vector<unsigned char> &pixels,
                   int &w, int &h) {
  static void *lib = nullptr;
  static bool tried = false;
  if (!tried) {
    tried = true;
    lib = dlopen("libpng16.so.16", RTLD_LAZY | RTLD_GLOBAL);
    if (!lib)
      lib = dlopen("libpng16.so", RTLD_LAZY | RTLD_GLOBAL);
  }
  if (!lib) {
    logf("skybox: libpng16 not available");
    return false;
  }
  using BeginFn = int (*)(PngImage *, const char *);
  using FinishFn = int (*)(PngImage *, void *, void *, int32_t, void *);
  using FreeFn = void (*)(PngImage *);
  static BeginFn begin =
      (BeginFn)dlsym(lib, "png_image_begin_read_from_file");
  static FinishFn finish = (FinishFn)dlsym(lib, "png_image_finish_read");
  static FreeFn free_img = (FreeFn)dlsym(lib, "png_image_free");
  if (!begin || !finish || !free_img) {
    logf("skybox: libpng16 simplified API missing");
    return false;
  }

  PngImage img{};
  img.version = 1;   // PNG_IMAGE_VERSION
  img.format = 0x03; // PNG_FORMAT_RGBA
  if (!begin(&img, path)) {
    logf("skybox: cannot open %s (%s)", path,
         img.message[0] ? img.message : "read error");
    return false;
  }
  if (img.width == 0 || img.height == 0 || img.width > 8192 ||
      img.height > 8192) {
    logf("skybox: %s has unsupported size %ux%u", path, img.width, img.height);
    free_img(&img);
    return false;
  }
  pixels.assign((size_t)img.width * img.height * 4, 255);
  if (!finish(&img, nullptr, pixels.data(), 0, nullptr)) {
    logf("skybox: cannot decode %s (%s)", path,
         img.message[0] ? img.message : "decode error");
    pixels.clear();
    free_img(&img);
    return false;
  }
  w = (int)img.width;
  h = (int)img.height;
  free_img(&img);
  return true;
}

std::vector<unsigned char> g_sky_pixels;
int g_sky_px_w = 0, g_sky_px_h = 0;

// ITextureRegenerator has two virtuals: RegenerateTextureBits then Release.
// This build has no IMaterialSystem::CreateTextureFromBits (its interface stops
// at GetDisplayDeviceName), so the pixels are uploaded through a procedural
// texture + regenerator instead.
class SkyRegenerator {
public:
  virtual void RegenerateTextureBits(void *texture, void *vtf, void *rect) {
    (void)texture;
    (void)rect;
    if (!vtf || g_sky_pixels.empty())
      return;
    using IntFn = int (*)(void *);
    using PitchFn = int (*)(void *, int);
    using DataFn = unsigned char *(*)(void *, int, int, int);
    // IVTFTexture vtable: dtor takes 2 slots, then Init, so Width=15,
    // Height=16, RowSizeInBytes=19, ImageData(frame,face,mip)=39.
    int w = vfunc<IntFn>(vtf, 15)(vtf);            // IVTFTexture::Width
    int h = vfunc<IntFn>(vtf, 16)(vtf);            // IVTFTexture::Height
    if (w <= 0 || h <= 0)
      return;
    int pitch = vfunc<PitchFn>(vtf, 19)(vtf, 0);   // RowSizeInBytes(0)
    unsigned char *dst = vfunc<DataFn>(vtf, 39)(vtf, 0, 0, 0); // ImageData
    if (!dst || pitch <= 0)
      return;
    int rows = h < g_sky_px_h ? h : g_sky_px_h;
    int src_stride = g_sky_px_w * 4;
    int copy = w * 4;
    if (copy > src_stride)
      copy = src_stride;
    for (int y = 0; y < rows; y++) {
      const unsigned char *src =
          g_sky_pixels.data() + (size_t)y * (size_t)src_stride;
      memcpy(dst + (size_t)y * (size_t)pitch, src, (size_t)copy);
    }
  }
  virtual void Release() {}
};

SkyRegenerator g_sky_regenerator;

void *g_sky_tex = nullptr;
bool g_sky_tex_tried = false;
bool g_sky_applied = false;
bool g_sky_reload = false;
double g_sky_retry_at = 0.0;
bool g_sky_fail_logged = false;

struct SkyOrig {
  std::string material;
  std::string var;
  std::string value; // fallback if the original texture pointer is gone
  void *texture;
};
std::vector<SkyOrig> g_sky_orig;

double now_sec() {
  struct timespec ts;
  clock_gettime(CLOCK_MONOTONIC, &ts);
  return (double)ts.tv_sec + (double)ts.tv_nsec / 1e9;
}

bool is_sky_material(const char *name, const char *group) {
  if (!plausible_name(name) || !plausible_name(group))
    return false;
  return strncmp(group, GROUP_SKYBOX, strlen(GROUP_SKYBOX)) == 0 ||
         strncmp(name, "skybox/", 7) == 0;
}

void record_orig(const char *material, const char *var, const char *value,
                 void *texture) {
  if (!material || !var)
    return;
  for (auto &r : g_sky_orig) {
    if (r.material == material && r.var == var)
      return;
  }
  g_sky_orig.push_back(
      {material, var, value ? value : "", texture});
}

int apply_sky_texture() {
  void *ms = material_system();
  if (!ms || !g_sky_tex)
    return 0;
  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 0;
  unsigned short inv = invalid(ms);
  int seen = 0, hits = 0;
  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 (!is_sky_material(name, group))
      continue;
    using FindVarFn = void *(*)(void *, const char *, bool *, bool);
    using GetStrFn = const char *(*)(void *);
    using SetTexFn = void (*)(void *, void *);
    auto find_var = vfunc<FindVarFn>(mat, 11); // IMaterial::FindVar

    static const char *vars[] = {"$basetexture", "$hdrbasetexture",
                                 "$hdrcompressedtexture", nullptr};
    for (int vi = 0; vars[vi]; vi++) {
      bool found = false;
      void *var = find_var(mat, vars[vi], &found, false);
      if (!found || !var)
        continue;
      using GetTexFn = void *(*)(void *);
      auto vget = vfunc<GetStrFn>(var, 6);      // GetStringValue
      auto vgettex = vfunc<GetTexFn>(var, 0);   // GetTextureValue
      auto vset = vfunc<SetTexFn>(var, 14);     // SetTextureValue
      const char *orig = vget(var);
      void *orig_tex = vgettex(var);
      record_orig(name, vars[vi], orig, orig_tex);
      vset(var, g_sky_tex);
      if (vi == 0)
        hits++;
    }
  }
  return hits;
}

void restore_sky_texture() {
  if (g_sky_orig.empty()) {
    g_sky_applied = false;
    return;
  }
  void *ms = material_system();
  if (!ms) {
    g_sky_orig.clear();
    g_sky_applied = false;
    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) {
    g_sky_orig.clear();
    g_sky_applied = false;
    return;
  }
  using FindVarFn = void *(*)(void *, const char *, bool *, bool);
  using SetStrFn = void (*)(void *, const char *);
  using SetTexFn = void (*)(void *, void *);
  unsigned short inv = invalid(ms);
  int seen = 0;
  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 (!is_sky_material(name, group))
      continue;
    for (auto &r : g_sky_orig) {
      if (r.material != name)
        continue;
      bool found = false;
      void *var = vfunc<FindVarFn>(mat, 11)(mat, r.var.c_str(), &found, false);
      if (!found || !var)
        continue;
      if (r.texture)
        vfunc<SetTexFn>(var, 14)(var, r.texture); // back to the map texture
      else if (!r.value.empty())
        vfunc<SetStrFn>(var, 5)(var, r.value.c_str());
    }
  }
  g_sky_orig.clear();
  g_sky_applied = false;
}

void load_sky_texture() {
  g_sky_tex_tried = true;
  void *ms = material_system();
  if (!ms) {
    logf("skybox: material system unavailable");
    return;
  }
  std::vector<unsigned char> pixels;
  int w = 0, h = 0;
  const char *path = config_file_cstr("skybox.png");
  if (!load_png_rgba(path, pixels, w, h)) {
    if (!g_sky_fail_logged) {
      g_sky_fail_logged = true;
      toastf(TOAST_ERROR, "Skybox image missing or unreadable: %s", path);
    }
    return;
  }
  g_sky_pixels.swap(pixels);
  g_sky_px_w = w;
  g_sky_px_h = h;

  // The procedural texture keeps its own copy through the regenerator, which
  // is called on Download() and again on device restore.
  using CreateProcFn = void *(*)(void *, const char *, const char *, int, int,
                                 int, int);
  g_sky_tex = vfunc<CreateProcFn>(ms, 81)(
      ms, "hl2hake/skybox", GROUP_SKYBOX, w, h, 0 /* RGBA8888 */,
      0x10C /* CLAMPS|CLAMPT|NOMIP */);
  if (!g_sky_tex) {
    logf("skybox: CreateProceduralTexture failed for %dx%d", w, h);
    return;
  }
  using SetRegenFn = void (*)(void *, void *);
  using DownloadFn = void (*)(void *, void *, int);
  vfunc<SetRegenFn>(g_sky_tex, 12)(g_sky_tex, &g_sky_regenerator);
  vfunc<DownloadFn>(g_sky_tex, 13)(g_sky_tex, nullptr, 0);
  g_sky_fail_logged = false;
  logf("skybox: image %s (%dx%d) uploaded", path, w, h);
}

} // namespace

void skybox_invalidate() {
  // Level change: re-apply on the new map. Keep the captured originals: with
  // the same skybox the same material objects (still showing our texture) are
  // reused, and the saved texture pointers are what lets us restore them.
  g_sky_applied = false;
  g_sky_retry_at = 0.0;
}

void skybox_reload_image() {
  restore_sky_texture();
  g_sky_tex = nullptr;
  g_sky_tex_tried = false;
  g_sky_reload = true;
  g_sky_retry_at = 0.0;
  g_sky_fail_logged = false;
}

void skybox_update() {
  bool on = feature_active(FEAT_SKYBOX);
  if (!on) {
    if (g_sky_applied || !g_sky_orig.empty())
      restore_sky_texture();
    return;
  }
  if (g_sky_reload) {
    g_sky_reload = false;
    restore_sky_texture();
  }
  if (g_sky_applied)
    return;
  double now = now_sec();
  if (now < g_sky_retry_at)
    return;
  if (!g_sky_tex && !g_sky_tex_tried)
    load_sky_texture();
  if (!g_sky_tex) {
    // The sky materials may not be loaded yet (menu, level transition). Try
    // again in a moment; the PNG itself is only re-read on Reload.
    g_sky_retry_at = now + 1.0;
    return;
  }
  int hits = apply_sky_texture();
  if (hits > 0) {
    g_sky_applied = true;
    logf("skybox: image applied to %d sky materials", hits);
  } else {
    g_sky_retry_at = now + 1.0;
  }
}