Silent aim: restore view at FRAME_RENDER_START; preserve movement

- hook CHLClient::FrameStageNotify (vtable slot 35) and at FRAME_RENDER_START
  re-apply the player's original view angles after the engine has consumed the
  aimed usercmd; this fixes the slow pull with high-RPM weapons and the
  revolver leaving the view on the target
- silent aim also rewrites forwardmove/sidemove so the world-space movement
  wish vector is unchanged by the temporary aim angles

1 files changed, 31 insertions, 2 deletions

diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index 89d6b89..0491fd9 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -278,6 +278,31 @@ static void do_move(int seq) {
 using CreateMoveFn = bool (*)(void *, int, float, bool);
 static CreateMoveFn oCreateMove = nullptr;
 
+using FrameStageFn = void (*)(void *, int);
+static FrameStageFn oFrameStageNotify = nullptr;
+static QAngle g_silent_restore_angles{};
+static bool g_silent_restore_pending = false;
+
+void set_silent_restore(const QAngle &angles) {
+  g_silent_restore_angles = angles;
+  g_silent_restore_pending = true;
+}
+
+// FRAME_RENDER_START (ClientFrameStage_t: -1 undefined, 0 START, ...,
+// 4 NET_UPDATE_END, 5 RENDER_START).
+static void hkdFrameStageNotify(void *self, int stage) {
+  if (oFrameStageNotify)
+    oFrameStageNotify(self, stage);
+  if (stage == 5 && g_silent_restore_pending) {
+    g_silent_restore_pending = false;
+    if (g_iface.engine) {
+      QAngle a = g_silent_restore_angles;
+      using SetViewFn = void (*)(void *, QAngle *);
+      vfunc<SetViewFn>(g_iface.engine, 20)(g_iface.engine, &a);
+    }
+  }
+}
+
 using DrawPrintTextFn = void (*)(void *self, const wchar_t *text, int len, int drawType);
 static DrawPrintTextFn oDrawPrintText = nullptr;
 using PaintTraverseExFn = void (*)(void *, long, bool);
@@ -345,9 +370,13 @@ static void install_hook() {
   memcpy(newvt, vt, SLOTS * sizeof(void *));
   oCreateMove = (CreateMoveFn)vt[21];
   newvt[21] = (void *)&hkdCreateMove;
+  oFrameStageNotify = (FrameStageFn)vt[35];
+  newvt[35] = (void *)&hkdFrameStageNotify;
   VTABLE(g_iface.client) = newvt;
-  logf("hook installed: CreateMove %p -> %p (orig %p)", vt[21],
-       (void *)&hkdCreateMove, (void *)oCreateMove);
+  logf("hook installed: CreateMove %p -> %p (orig %p), FrameStageNotify %p "
+       "-> %p (orig %p)",
+       vt[21], (void *)&hkdCreateMove, (void *)oCreateMove, vt[35],
+       (void *)&hkdFrameStageNotify, (void *)oFrameStageNotify);
 }
 
 // ---------------------------------------------------------------------------