GUI: allow movement while open; freeze look and block bind capture

Feedback pass on the preview shell:

- Freeze the rendered view explicitly in CreateMove and again at
  FRAME_RENDER_START; CInput was still letting mouse look move the camera.
- Allow normal WASD/jump/duck movement while the GUI is open; strip
  attack/use/impulse/weapon selection so GUI clicks do not fire.
- While bind capture is active, block all game input.
- Esc no longer closes the GUI; it only cancels bind capture. F2 or the
  title-bar X close the preview.
- Interpose SDL_ShowCursor / SDL_SetRelativeMouseMode / warp / window grab so
  the game cannot re-capture or hide the native cursor while the GUI is open.

1 files changed, 29 insertions, 9 deletions

diff --git a/src/hl2h.cpp b/src/hl2h.cpp
index c0c27af..a0e6b53 100644
--- a/src/hl2h.cpp
+++ b/src/hl2h.cpp
@@ -546,10 +546,23 @@ static void do_move(int seq, float frametime) {
     cmd->viewangles[0] = f.x;
     cmd->viewangles[1] = f.y;
     cmd->viewangles[2] = f.z;
-    cmd->forwardmove = 0.0f;
-    cmd->sidemove = 0.0f;
-    cmd->upmove = 0.0f;
-    cmd->buttons = 0;
+    // Freeze the rendered view explicitly: CInput may not push the modified
+    // command view back to the engine if the client mode returns false.
+    if (g_iface.engine) {
+      QAngle set = f;
+      using SetViewFn = void (*)(void *, QAngle *);
+      vfunc<SetViewFn>(g_iface.engine, 20)(g_iface.engine, &set);
+    }
+    if (gui_bind_capture_active()) {
+      // Bind capture must not move/act in the game while keys are sampled.
+      cmd->forwardmove = 0.0f;
+      cmd->sidemove = 0.0f;
+      cmd->upmove = 0.0f;
+      cmd->buttons = 0;
+    } else {
+      // Movement is allowed while the GUI is open, but not look/attack/use.
+      cmd->buttons &= (IN_JUMP | IN_DUCK);
+    }
     cmd->impulse = 0;
     cmd->weaponselect = 0;
     cmd->weaponsubtype = 0;
@@ -670,12 +683,19 @@ void set_silent_restore(const QAngle &angles) {
 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;
+  if (stage == 5) {
+    if (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);
+      }
+    }
+    if (gui_is_open() && g_iface.engine) {
+      QAngle f = gui_frozen_view();
       using SetViewFn = void (*)(void *, QAngle *);
-      vfunc<SetViewFn>(g_iface.engine, 20)(g_iface.engine, &a);
+      vfunc<SetViewFn>(g_iface.engine, 20)(g_iface.engine, &f);
     }
   }
 }