fast forwarding replays

src/assets/ba_data/python/bascenev1/__init__.py

@@ -120,7 +120,7 @@ from _bascenev1 import (
     release_keyboard_input,
     reset_random_player_names,
     resume_replay,
-    rewind_replay,
+    seek_replay,
     broadcastmessage,
     SessionData,
     SessionPlayer,
@@ -401,7 +401,7 @@ __all__ = [
     'release_keyboard_input',
     'reset_random_player_names',
     'resume_replay',
-    'rewind_replay',
+    'seek_replay',
     'safecolor',
     'screenmessage',
     'SceneV1AppMode',

src/ballistica/scene_v1/python/methods/python_methods_scene.cc

@@ -1568,32 +1568,37 @@ static PyMethodDef PyResumeReplayDef = {
     "Resumes replay.",
 };
 
-// ------------------------ rewind_replay --------------------------------------
+// -------------------------- seek_replay --------------------------------------
 
-static auto PyRewindReplay(PyObject* self, PyObject* args) -> PyObject* {
+static auto PySeekReplay(PyObject* self, PyObject* args) -> PyObject* {
   BA_PYTHON_TRY;
   auto* appmode = SceneV1AppMode::GetActiveOrThrow();
   auto* session =
       dynamic_cast<ClientSessionReplay*>(appmode->GetForegroundSession());
   if (session == nullptr) {
     throw Exception(
-        "Attempting to rewind a replay not in replay session context.");
+        "Attempting to seek a replay not in replay session context.");
   }
-  session->RestoreState(session->base_time() - 2'000);
+  float delta;
+  if (!PyArg_ParseTuple(args, "f", &delta)) {
+    return nullptr;
+  }
+  session->SeekTo(session->base_time()
+                  + static_cast<millisecs_t>(delta * 1'000));
   Py_RETURN_NONE;
   BA_PYTHON_CATCH;
 }
 
-static PyMethodDef PyRewindReplayDef = {
+static PyMethodDef PySeekReplayDef = {
-    "rewind_replay",  // name
+    "seek_replay",  // name
-    PyRewindReplay,   // method
+    PySeekReplay,   // method
-    METH_VARARGS,     // flags
+    METH_VARARGS,   // flags
 
-    "rewind_replay() -> None\n"
+    "seek_replay(delta: float) -> None\n"
     "\n"
     "(internal)\n"
     "\n"
-    "Rewinds replay.",
+    "Rewind or fast-forward replay.",
 };
 
 // ----------------------- reset_random_player_names ---------------------------
@@ -1874,7 +1879,7 @@ auto PythonMethodsScene::GetMethods() -> std::vector<PyMethodDef> {
       PySetReplaySpeedExponentDef,
       PyGetReplaySpeedExponentDef,
       PyIsReplayPausedDef,
-      PyRewindReplayDef,
+      PySeekReplayDef,
       PyPauseReplayDef,
       PyResumeReplayDef,
       PySetDebugSpeedExponentDef,

src/ballistica/scene_v1/support/client_session_replay.cc

@@ -2,6 +2,8 @@
 
 #include "ballistica/scene_v1/support/client_session_replay.h"
 
+#include <algorithm>
+
 #include "ballistica/base/assets/assets.h"
 #include "ballistica/base/networking/networking.h"
 #include "ballistica/base/support/huffman.h"
@@ -14,11 +16,22 @@
 
 namespace ballistica::scene_v1 {
 
+static const millisecs_t kReplayStateDumpIntervalMillisecs = 500;
+
 auto ClientSessionReplay::GetActualTimeAdvanceMillisecs(
     double base_advance_millisecs) -> double {
+  if (is_fast_forwarding_) {
+    if (base_time() < fast_forward_base_time_) {
+      return std::min(
+          base_advance_millisecs * 8,
+          static_cast<double>(fast_forward_base_time_ - base_time()));
+    }
+    is_fast_forwarding_ = false;
+  }
   auto* appmode = SceneV1AppMode::GetActiveOrFatal();
   if (appmode->is_replay_paused()) {
-    return 0.001;
+    // FIXME: seeking a replay results in black screen here
+    return 0;
   }
   return base_advance_millisecs * pow(2.0f, appmode->replay_speed_exponent());
 }
@@ -136,8 +149,8 @@ void ClientSessionReplay::FetchMessages() {
   while (commands().empty()) {
     // Before we read next message, let's save our current state
     // if we didn't that for too long.
-    unsaved_messages_count_ += 1;
+    if (base_time() >= (states_.empty() ? 0 : states_.back().base_time_)
-    if (unsaved_messages_count_ > 50) {
+                           + kReplayStateDumpIntervalMillisecs) {
       SessionStream out(nullptr, false);
       DumpFullState(&out);
 
@@ -148,7 +161,7 @@ void ClientSessionReplay::FetchMessages() {
       fflush(file_);
       current_state_.file_position_ = ftell(file_);
       current_state_.message_ = out.GetOutMessage();
-      SaveState();
+      states_.push_back(current_state_);
     }
 
     std::vector<uint8_t> buffer;
@@ -218,7 +231,6 @@ void ClientSessionReplay::FetchMessages() {
     for (auto&& i : connections_to_clients_) {
       i->SendReliableMessage(data_decompressed);
     }
-    message_fetch_num_++;
   }
 }
 
@@ -238,6 +250,10 @@ void ClientSessionReplay::OnReset(bool rewind) {
   // Handles base resetting.
   ClientSession::OnReset(rewind);
 
+  // Hack or not, but let's reset our fast-forward flag here, in case we were
+  // asked to seek replay further than it's length.
+  is_fast_forwarding_ = false;
+
   // If we've got any clients attached to us, tell them to reset as well.
   for (auto&& i : connections_to_clients_) {
     i->SendReliableMessage(std::vector<uint8_t>(1, BA_MESSAGE_SESSION_RESET));
@@ -282,29 +298,44 @@ void ClientSessionReplay::OnReset(bool rewind) {
   }
 }
 
-void ClientSessionReplay::SaveState() {
+void ClientSessionReplay::SeekTo(millisecs_t to_base_time) {
-  unsaved_messages_count_ = 0;
+  is_fast_forwarding_ = false;
-  states_.push_back(current_state_);
+  if (to_base_time < base_time()) {
-}
+    auto it = std::lower_bound(
-
+        states_.rbegin(), states_.rend(), to_base_time,
-void ClientSessionReplay::RestoreState(millisecs_t to_base_time) {
+        [&](const IntermediateState& state, millisecs_t time) -> bool {
-  ScreenMessage("was: " + std::to_string(base_time()) + "ms");
+          return state.base_time_ > time;
-  ScreenMessage("want: " + std::to_string(to_base_time) + "ms");
+        });
-
+    if (it == states_.rend()) {
-  while (!states_.empty() && states_.back().base_time_ > to_base_time) {
+      Reset(true);
-    states_.pop_back();
+    } else {
-  }
+      current_state_ = *it;
-
+      RestoreFromCurrentState();
-  if (states_.empty()) {
+    }
-    Reset(true);
   } else {
-    current_state_ = states_.back();
+    auto it = std::lower_bound(
-    RestoreFromCurrentState();
+        states_.begin(), states_.end(), to_base_time,
+        [&](const IntermediateState& state, millisecs_t time) -> bool {
+          return state.base_time_ < time;
+        });
+    if (it == states_.end()) {
+      if (!states_.empty()) {
+        current_state_ = states_.back();
+        RestoreFromCurrentState();
+      }
+      // Let's speed up replay a bit
+      // (and we'll collect needed states along).
+      is_fast_forwarding_ = true;
+      fast_forward_base_time_ = to_base_time;
+    } else {
+      current_state_ = *it;
+      RestoreFromCurrentState();
+    }
   }
 }
 
 void ClientSessionReplay::RestoreFromCurrentState() {
-  // what to do with messages_fetch_num_? is it used somewhere at all?
+  // FIXME: calling reset here causes background music to start over
   Reset(true);
   fseek(file_, current_state_.file_position_, SEEK_SET);
 

src/ballistica/scene_v1/support/client_session_replay.h

@@ -28,8 +28,8 @@ class ClientSessionReplay : public ClientSession,
 
   void Error(const std::string& description) override;
   void FetchMessages() override;
-  void SaveState();
+
-  void RestoreState(millisecs_t to_base_time);
+  void SeekTo(millisecs_t to_base_time);
 
  private:
   struct IntermediateState {
@@ -38,7 +38,7 @@ class ClientSessionReplay : public ClientSession,
     std::vector<std::vector<uint8_t>> correction_messages_;
 
     // A position in replay file where we should continue from.
-    long file_position_;
+    int64_t file_position_;
 
     millisecs_t base_time_;
   };
@@ -49,9 +49,9 @@ class ClientSessionReplay : public ClientSession,
   std::vector<IntermediateState> states_;
   IntermediateState current_state_;
 
-  int unsaved_messages_count_{};
+  bool is_fast_forwarding_{};
+  millisecs_t fast_forward_base_time_{};
 
-  uint32_t message_fetch_num_{};
   bool have_sent_client_message_{};
   std::vector<ConnectionToClient*> connections_to_clients_;
   std::vector<ConnectionToClient*> connections_to_clients_ignored_;