second attempt at "nice" client state correction

[blank.git] / src / client / client.cpp

diff --git a/src/client/client.cpp b/src/client/client.cpp
index 8a3d1c89c98e36a17c645852172f3d92d9cfb0eb..72d860d97772e75706d8ae81e2f5df5ec90fa756 100644 (file)
--- a/src/client/client.cpp
+++ b/src/client/client.cpp
@@ -56,7 +56,8 @@ InteractiveState::InteractiveState(MasterState &master, uint32_t player_id)
 )
 , chunk_renderer(*interface.GetPlayer().chunks)
 , skeletons()
-, update_timer(16) {
+, loop_timer(16)
+, player_hist() {
        TextureIndex tex_index;
        master.GetEnv().loader.LoadBlockTypes("default", block_types, tex_index);
        chunk_renderer.LoadTextures(master.GetEnv().loader, tex_index);
@@ -64,7 +65,7 @@ InteractiveState::InteractiveState(MasterState &master, uint32_t player_id)
        skeletons.Load();
        // TODO: better solution for initializing HUD
        interface.SelectNext();
-       update_timer.Start();
+       loop_timer.Start();
 }
 
 void InteractiveState::OnEnter() {
@@ -100,18 +101,22 @@ void InteractiveState::Handle(const SDL_Event &event) {
 }
 
 void InteractiveState::Update(int dt) {
+       loop_timer.Update(dt);
        master.Update(dt);
 
        interface.Update(dt);
-       world.Update(dt);
+       int world_dt = 0;
+       while (loop_timer.HitOnce()) {
+               world.Update(loop_timer.Interval());
+               world_dt += loop_timer.Interval();
+               loop_timer.PopIteration();
+       }
        chunk_renderer.Update(dt);
 
-       update_timer.Update(dt);
-
        Entity &player = *interface.GetPlayer().entity;
 
-       if (update_timer.Hit()) {
-               master.GetClient().SendPlayerUpdate(player);
+       if (world_dt > 0) {
+               PushPlayerUpdate(player, world_dt);
        }
 
        glm::mat4 trans = player.Transform(player.ChunkCoords());
@@ -122,6 +127,83 @@ void InteractiveState::Update(int dt) {
        master.GetEnv().audio.Orientation(dir, up);
 }
 
+void InteractiveState::PushPlayerUpdate(const Entity &player, int dt) {
+       std::uint16_t packet = master.GetClient().SendPlayerUpdate(player);
+       if (player_hist.size() < 16) {
+               player_hist.emplace_back(player.GetState(), dt, packet);
+       } else {
+               auto entry = player_hist.begin();
+               entry->state = player.GetState();
+               entry->delta_t = dt;
+               entry->packet = packet;
+               player_hist.splice(player_hist.end(), player_hist, entry);
+       }
+}
+
+void InteractiveState::MergePlayerCorrection(uint16_t seq, const EntityState &corrected_state) {
+       if (player_hist.empty()) return;
+
+       auto entry = player_hist.begin();
+       auto end = player_hist.end();
+
+       // we may have received an older packet
+       int pack_diff = int16_t(seq) - int16_t(entry->packet);
+       if (pack_diff < 0) {
+               // indeed we have, just ignore it
+               return;
+       }
+
+       // drop anything older than the fix
+       while (entry != end) {
+               pack_diff = int16_t(seq) - int16_t(entry->packet);
+               if (pack_diff > 0) {
+                       entry = player_hist.erase(entry);
+               } else {
+                       break;
+               }
+       }
+
+       EntityState replay_state(corrected_state);
+       EntityState &player_state = interface.GetPlayer().entity->GetState();
+
+       if (entry != end) {
+               entry->state.chunk_pos = replay_state.chunk_pos;
+               entry->state.block_pos = replay_state.block_pos;
+               ++entry;
+       }
+
+       while (entry != end) {
+               replay_state.velocity = entry->state.velocity;
+               replay_state.Update(entry->delta_t);
+               entry->state.chunk_pos = replay_state.chunk_pos;
+               entry->state.block_pos = replay_state.block_pos;
+               ++entry;
+       }
+
+       glm::vec3 displacement(replay_state.Diff(player_state));
+       const float disp_squared = dot(displacement, displacement);
+
+       if (disp_squared < 16.0f * numeric_limits<float>::epsilon()) {
+               return;
+       }
+
+       // if offset > 10cm, warp the player
+       // otherwise, move at most 1cm per frame towards
+       // the fixed position (160ms, so shouldn't be too noticeable)
+       constexpr float warp_thresh = 0.01f; // (1/10)^2
+       constexpr float max_disp = 0.0001f; // (1/100)^2
+
+       if (disp_squared > warp_thresh) {
+               player_state.chunk_pos = replay_state.chunk_pos;
+               player_state.block_pos = replay_state.block_pos;
+       } else if (disp_squared < max_disp) {
+               player_state.block_pos += displacement;
+       } else {
+               displacement *= 0.01f / sqrt(disp_squared);
+               player_state.block_pos += displacement;
+       }
+}
+
 void InteractiveState::Render(Viewport &viewport) {
        Entity &player = *interface.GetPlayer().entity;
        viewport.WorldPosition(player.Transform(player.ChunkCoords()));
@@ -322,5 +404,18 @@ void MasterState::ClearEntity(uint32_t entity_id) {
        update_status.erase(entity_id);
 }
 
+void MasterState::On(const Packet::PlayerCorrection &pack) {
+       if (!state) {
+               cout << "got player correction without a player :S" << endl;
+               Quit();
+               return;
+       }
+       uint16_t pack_seq;
+       EntityState corrected_state;
+       pack.ReadPacketSeq(pack_seq);
+       pack.ReadPlayerState(corrected_state);
+       state->MergePlayerCorrection(pack_seq, corrected_state);
+}
+
 }
 }