1 files changed, 63 insertions, 0 deletions
diff --git a/source/game/StarInterpolationTracker.cpp b/source/game/StarInterpolationTracker.cpp
new file mode 100644
index 0000000..494c52e
--- /dev/null
+++ b/source/game/StarInterpolationTracker.cpp
@@ -0,0 +1,63 @@
+#include "StarInterpolationTracker.hpp"
+#include "StarRoot.hpp"
+#include "StarAssets.hpp"
+
+namespace Star {
+
+InterpolationTracker::InterpolationTracker(Json config) {
+  if (config.isNull()) {
+    config = JsonObject();
+  } else if (config.type() == Json::Type::String) {
+    auto assets = Root::singleton().assets();
+    config = assets->json(config.toString());
+  }
+
+  m_interpolationEnabled = config.getBool("interpolationEnabled", false);
+  m_entityUpdateDelta = config.getUInt("enittyUpdateDelta", 3);
+  m_stepLead = config.getUInt("stepLead", 0);
+  m_extrapolationHint = config.getUInt("extrapolationHint", 0);
+  m_stepTrackFactor = config.getDouble("stepTrackFactor", 1.0);
+  m_stepMaxDistance = config.getDouble("stepMaxDistance", 0.0);
+
+  m_currentStep = 0.0;
+}
+
+bool InterpolationTracker::interpolationEnabled() const {
+  return m_interpolationEnabled;
+}
+
+unsigned InterpolationTracker::extrapolationHint() const {
+  if (m_interpolationEnabled)
+    return m_extrapolationHint;
+  else
+    return 0;
+}
+
+unsigned InterpolationTracker::entityUpdateDelta() const {
+  return m_entityUpdateDelta;
+}
+
+void InterpolationTracker::receiveStepUpdate(double remoteStep) {
+  m_lastStepUpdate = remoteStep;
+}
+
+void InterpolationTracker::update(double newLocalStep) {
+  double dt = newLocalStep - m_currentStep;
+  m_currentStep = newLocalStep;
+  if (!m_predictedStep || !m_lastStepUpdate || dt < 0.0f) {
+    m_predictedStep = m_lastStepUpdate;
+  } else {
+    *m_lastStepUpdate += dt;
+    *m_predictedStep += dt;
+    *m_predictedStep += (*m_lastStepUpdate - *m_predictedStep) * m_stepTrackFactor;
+    m_predictedStep = clamp<double>(*m_predictedStep, *m_lastStepUpdate - m_stepMaxDistance, *m_lastStepUpdate + m_stepMaxDistance);
+  }
+}
+
+float InterpolationTracker::interpolationLeadSteps() const {
+  if (!m_interpolationEnabled || !m_predictedStep || !m_lastStepUpdate)
+    return 0.0f;
+  return *m_lastStepUpdate - *m_predictedStep + m_stepLead;
+}
+
+}