begin serversimulation

src/td/simulation/ClientSimulation.cpp

@@ -0,0 +1,95 @@
+#include <td/simulation/ClientSimulation.h>
+
+#include <chrono>
+
+namespace td {
+namespace sim {
+
+const protocol::LockStep ClientSimulation::EMPTY_LOCKSTEP;
+
+std::uint64_t GetTime() {
+	return static_cast<std::uint64_t>(
+		std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock().now().time_since_epoch()).count());
+}
+
+ClientSimulation::ClientSimulation(game::World& a_World, GameHistory&& a_History, std::uint64_t a_StepTime) :
+	m_StepTime(a_StepTime),
+	m_World(a_World),
+	m_CurrentTime(0),
+	m_LastTime(GetTime()),
+	m_CurrentStep(0),
+	m_LastSnapshot(std::make_shared<WorldSnapshot>()),
+	m_LastValidStep(0) {
+	m_History.reserve(a_History.size());
+	for (auto&& lockstep : a_History) {
+		m_History.emplace_back(std::move(lockstep));
+	}
+	Step();
+}
+
+ClientSimulation::ClientSimulation(game::World& a_World, std::uint64_t a_StepTime) :
+	m_StepTime(a_StepTime),
+	m_World(a_World),
+	m_History(std::numeric_limits<std::uint16_t>::max()),
+	m_CurrentTime(0),
+	m_LastTime(GetTime()),
+	m_CurrentStep(0),
+	m_LastSnapshot(std::make_shared<WorldSnapshot>()),
+	m_LastValidStep(0) {
+	Step();
+}
+
+float ClientSimulation::Update() {
+	// TODO: handle freezes (m_CurrentTime > 2 * m_StepTime)
+	m_CurrentTime += GetTime() - m_LastTime;
+	m_LastTime = GetTime();
+	if (m_CurrentTime > m_StepTime) {
+		Step();
+		m_CurrentTime -= m_StepTime;
+	}
+	return (float)m_CurrentTime / (float)m_StepTime;
+}
+
+void ClientSimulation::Step() {
+	const auto& step = m_History[m_CurrentStep];
+	if (step.has_value()) {
+		m_LastSnapshot = m_World.Tick(step.value(), FpFloat(m_StepTime) / FpFloat(1000));
+		m_LastValidStep = m_CurrentStep;
+	} else {
+		m_World.Tick(EMPTY_LOCKSTEP, FpFloat(m_StepTime) / FpFloat(1000));
+	}
+	m_CurrentStep++;
+}
+
+void ClientSimulation::Handle(const protocol::packets::LockStepsPacket& a_LockSteps) {
+	const auto& steps = a_LockSteps->m_LockSteps;
+	for (std::size_t i = 0; i < LOCKSTEP_BUFFER_SIZE; i++) {
+		m_History[a_LockSteps->m_FirstFrameNumber + i] = steps[i];
+	}
+	FastReplay();
+}
+
+void ClientSimulation::Handle(const protocol::packets::PredictCommandPacket& a_Predict) {
+	
+}
+
+void ClientSimulation::FastForward(std::size_t a_Count) {
+	for (std::size_t i = 0; i < a_Count; i++) {
+		Step();
+	}
+}
+
+void ClientSimulation::FastReplay() {
+	if (m_LastValidStep >= m_CurrentStep)
+		return;
+
+	m_World.ResetSnapshots(m_LastSnapshot, m_LastSnapshot);
+
+	const std::size_t stepCount = m_CurrentStep - m_LastValidStep;
+	m_CurrentStep = m_LastValidStep;
+	
+	FastForward(stepCount);
+}
+
+}  // namespace sim
+}  // namespace td