No spread: detect pellet draws from the FireBullets seed call

The ApplySpread random draws are not guaranteed to run in the player's frame
(the compiler can outline them), so the frame-based shooter check missed and
the shotgun kept its seed-minimised spread. The player's FireBullets
RandomSeed call now arms a short 8-draw window; the next RandomFloat draws
return 0. Keep the frame check as the other path. Remove the diagnostics used
to find this.

1 files changed, 22 insertions, 5 deletions

diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index 02bf584..8ab1a3e 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -482,6 +482,8 @@ static void (*g_real_random_seed)(int) = nullptr;
 static uintptr_t g_srv_base = 0;
 static uintptr_t g_local_server_player = 0;
 static bool g_seed_hook_installed = false;
+// Pellet-spread window armed by the player's FireBullets RandomSeed call.
+static volatile int g_spread_rand_left = 0;
 
 static void hkdSrvRandomSeed(int seed) {
   uintptr_t ret = (uintptr_t)__builtin_return_address(0);
@@ -502,6 +504,7 @@ static void hkdSrvRandomSeed(int seed) {
 
   if (local && g_server.contains(ret) && feature_active(FEAT_SPREAD) &&
       spread_no_spread_enabled()) {
+    g_spread_rand_left = 8;
     int pellets = g_spread_pellets;
     if (pellets < 1)
       pellets = 1;
@@ -590,19 +593,33 @@ static void install_seed_hook() {
 
 static float (*g_orig_uniform_float)(void *, float, float) = nullptr;
 static bool g_uniform_hook_installed = false;
+// g_spread_rand_left is set for a few draws right after the player's
+// FireBullets RandomSeed. The ApplySpread frame is not always the player's
+// (the compiler may outline it), so this window is the reliable signal.
 
 static float hkdUniformRandomFloat(void *self, float mn, float mx) {
-  if (g_local_server_player && feature_active(FEAT_SPREAD) &&
-      spread_no_spread_enabled()) {
+  bool enabled = g_local_server_player && feature_active(FEAT_SPREAD) &&
+                 spread_no_spread_enabled();
+  bool hit = false;
+  void *who = nullptr;
+  if (enabled) {
     void *frame = nullptr;
     __asm__ volatile("movl %%ebp, %0" : "=r"(frame));
     if (frame) {
-      frame = *(void **)frame; // caller's ebp (CBaseEntity::FireBullets)
-      void *who = frame ? *(void **)((char *)frame + 8) : nullptr;
+      frame = *(void **)frame; // caller's ebp
+      who = frame ? *(void **)((char *)frame + 8) : nullptr;
       if (who && (uintptr_t)who == g_local_server_player)
-        return 0.0f;
+        hit = true;
+    }
+    if (!hit && g_spread_rand_left > 0) {
+      // The next few draws after the player's FireBullets RandomSeed are the
+      // pellet spread, regardless of which function emits them.
+      hit = true;
+      g_spread_rand_left--;
     }
   }
+  if (hit)
+    return 0.0f;
   return g_orig_uniform_float ? g_orig_uniform_float(self, mn, mx) : mn;
 }