World tint: tint map-static props through IStudioRender

Most of the crates are prop_static, which have no client entity, so writing
m_clrRender only reached the three dynamic ones. Hook the StudioRender
interface (VStudioRender025) on the interface object's vtable: substitute the
prop colour in SetColorModulation/SetAlphaModulation while
DrawModelStaticProp is drawing a models/props model, and set the modulation
explicitly before the original draw in case the engine sets it just before the
call.

Vtable indices verified by disassembling CStudioRenderContext: 27 = three
float stores from the argument pointer, 28 = one float, 30 = the
DrawModelInfo_t-drawing entry with three arguments (the 2013 SDK header lists
these slots five positions earlier in this build).

4 files changed, 182 insertions, 1 deletions

diff --git a/build.sh b/build.sh
index b59f20e..b12f67b 100755
--- a/build.sh
+++ b/build.sh
@@ -3,6 +3,6 @@ set -e
 cd "$(dirname "$0")"
 g++ -m32 -O2 -std=c++17 -Wall -Wextra -Werror -fPIC -shared -fvisibility=hidden -fno-omit-frame-pointer \
     -o libhl2hake.so \
-    src/hl2h.cpp src/modules.cpp src/cinput.cpp src/netvars.cpp src/menu.cpp src/gui.cpp src/esp.cpp src/server.cpp src/bones.cpp src/vischeck.cpp src/world.cpp \
+    src/hl2h.cpp src/modules.cpp src/cinput.cpp src/netvars.cpp src/menu.cpp src/gui.cpp src/esp.cpp src/server.cpp src/bones.cpp src/vischeck.cpp src/world.cpp src/studio.cpp \
     -ldl -Wl,--no-undefined
 file libhl2hake.so
diff --git a/src/esp.cpp b/src/esp.cpp
index 9d041b0..67fbad2 100644
--- a/src/esp.cpp
+++ b/src/esp.cpp
@@ -1413,6 +1413,8 @@ void prop_tint_update() {
   static bool logged_missing = false;
   static bool logged_touched = false;
   bool on = feature_active(FEAT_WORLD_TINT) && g_tint_prop_on;
+  if (on)
+    studio_props_init();
   if (!on && !applied)
     return;
   if (!g_iface.entitylist || g_net.clr_render < 0) {
diff --git a/src/hl2h.h b/src/hl2h.h
index 779a241..3ccf7b5 100644
--- a/src/hl2h.h
+++ b/src/hl2h.h
@@ -298,6 +298,7 @@ void draw_text_col(int x, int y, const char *s, int r, int g, int b);
 void esp_draw();
 void esp_draw_items();
 void prop_tint_update();
+void studio_props_init();
 bool world_to_screen(const Vector &w, float &sx, float &sy);
 void set_silent_restore(const QAngle &angles);
 bool is_visible(const Vector &eye, const Vector &point,
diff --git a/src/studio.cpp b/src/studio.cpp
new file mode 100644
index 0000000..dd6f109
--- /dev/null
+++ b/src/studio.cpp
@@ -0,0 +1,178 @@
+// studio.cpp — colour static props at the StudioRender level.
+//
+// Dynamic props are tinted through their client entity's m_clrRender (see
+// esp.cpp). Map-static props have no entity: the engine's static-prop manager
+// calls IStudioRender::DrawModelStaticProp, and the colour modulation used for
+// the draw comes from IStudioRender::SetColorModulation. Hook both on the
+// interface object so the prop colour is substituted only while a prop model
+// is being drawn.
+//
+// VStudioRender025 vtable (verified against studiorender.so's
+// CStudioRenderContext vtable at .data.rel.ro):
+//   27 = SetColorModulation(float const*)
+//   28 = SetAlphaModulation(float)
+//   30 = DrawModelStaticProp(const DrawModelInfo_t&, const matrix3x4_t&, int)
+// (The 2013 SDK header lists these five slots earlier; this build's layout
+// has additional methods before them.)
+
+#include "hl2h.h"
+#include <cstdio>
+#include <cstring>
+#include <dlfcn.h>
+
+namespace {
+
+using SetColorFn = void (*)(void *, const float *);
+using SetAlphaFn = void (*)(void *, float);
+using DrawStaticFn = void (*)(void *, void *, void *, int);
+
+SetColorFn g_orig_set_color = nullptr;
+SetAlphaFn g_orig_set_alpha = nullptr;
+DrawStaticFn g_orig_draw_static = nullptr;
+
+bool g_install_tried = false;
+bool g_installed = false;
+int g_prop_depth = 0;
+
+bool prop_tint_on() {
+  return feature_active(FEAT_WORLD_TINT) && g_tint_prop_on;
+}
+
+void prop_color(float out[4]) {
+  out[0] = (float)g_tint_prop_rgb[0] / 255.0f;
+  out[1] = (float)g_tint_prop_rgb[1] / 255.0f;
+  out[2] = (float)g_tint_prop_rgb[2] / 255.0f;
+  out[3] = 1.0f;
+}
+
+// DrawModelInfo_t starts with studiohdr_t*; studiohdr_t::name is at +12
+// (id, version, checksum, then char name[64]).
+const char *info_model_name(void *info) {
+  if (!info)
+    return nullptr;
+  void *hdr = *(void **)info;
+  if (!hdr)
+    return nullptr;
+  const char *name = (const char *)hdr + 12;
+  size_t n = strnlen(name, 128);
+  if (n < 7 || n >= 128)
+    return nullptr;
+  for (size_t i = 0; i < n; i++) {
+    unsigned char c = (unsigned char)name[i];
+    if (c < 0x20 || c > 0x7e)
+      return nullptr;
+  }
+  return name;
+}
+
+bool is_prop_model(const char *name) {
+  return name && strncmp(name, "models/props", 12) == 0;
+}
+
+void hook_set_color(void *self, const float *color) {
+  if (g_prop_depth > 0 && prop_tint_on()) {
+    float c[4];
+    prop_color(c);
+    g_orig_set_color(self, c);
+    return;
+  }
+  g_orig_set_color(self, color);
+}
+
+void hook_set_alpha(void *self, float alpha) {
+  if (g_prop_depth > 0 && prop_tint_on()) {
+    g_orig_set_alpha(self, 1.0f);
+    return;
+  }
+  g_orig_set_alpha(self, alpha);
+}
+
+void hook_draw_static_prop(void *self, void *info, void *model_to_world,
+                           int flags) {
+  bool prop = prop_tint_on() && is_prop_model(info_model_name(info));
+  if (prop) {
+    // The engine may have set the modulation just before this call; override
+    // it here as well as from the SetColorModulation hook (the static-prop
+    // renderer can call it either side of DrawModelStaticProp).
+    float c[4];
+    prop_color(c);
+    g_orig_set_color(self, c);
+    g_orig_set_alpha(self, 1.0f);
+    g_prop_depth++;
+  }
+  g_orig_draw_static(self, info, model_to_world, flags);
+  if (prop)
+    g_prop_depth--;
+}
+
+std::string loaded_module_path(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;
+}
+
+} // namespace
+
+void studio_props_init() {
+  if (g_install_tried)
+    return;
+  g_install_tried = true;
+
+  std::string path = loaded_module_path("studiorender");
+  void *h = nullptr;
+  if (!path.empty())
+    h = dlopen(path.c_str(), RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
+  if (!h)
+    h = dlopen("studiorender.so", RTLD_NOLOAD | RTLD_LAZY | RTLD_GLOBAL);
+  if (!h) {
+    logf("studio: studiorender.so not loaded");
+    return;
+  }
+  auto cf = (CreateInterfaceFn)dlsym(h, "CreateInterface");
+  if (!cf) {
+    logf("studio: studiorender CreateInterface missing");
+    return;
+  }
+  void *sr = cf("VStudioRender025", nullptr);
+  if (!sr) {
+    logf("studio: VStudioRender025 not exposed");
+    return;
+  }
+
+  void **old_vt = *(void ***)sr;
+  if (!old_vt) {
+    logf("studio: interface has no vtable");
+    return;
+  }
+  static void *vt[49];
+  memcpy(vt, old_vt, sizeof(vt));
+
+  g_orig_set_color = (SetColorFn)vt[27];
+  g_orig_set_alpha = (SetAlphaFn)vt[28];
+  g_orig_draw_static = (DrawStaticFn)vt[30];
+  vt[27] = (void *)&hook_set_color;
+  vt[28] = (void *)&hook_set_alpha;
+  vt[30] = (void *)&hook_draw_static_prop;
+
+  *(void ***)sr = vt;
+  g_installed = true;
+  logf("studio: IStudioRender %p hooked (setcolor=%p drawstatic=%p)", sr,
+       (void *)g_orig_set_color, (void *)g_orig_draw_static);
+}