From d7780d8248eb696b44fc7b9ca43cab55cb0dff38 Mon Sep 17 00:00:00 2001
From: stiffly <adambylehn@hotmail.com>
Date: Mon, 18 Jan 2016 17:11:37 +0100
Subject: [PATCH] WIP implementing interpolation

---
 include/Engine/Network/EInterpolate.h | 20 +++++++++++
 include/Game/InterpolationSystem.h    | 42 ++++++++++++++++++++++
 src/Game/InterpolationSystem.cpp      | 50 +++++++++++++++++++++++++++
 3 files changed, 112 insertions(+)
 create mode 100644 include/Engine/Network/EInterpolate.h
 create mode 100644 include/Game/InterpolationSystem.h
 create mode 100644 src/Game/InterpolationSystem.cpp

diff --git a/include/Engine/Network/EInterpolate.h b/include/Engine/Network/EInterpolate.h
new file mode 100644
index 00000000..65038e49
--- /dev/null
+++ b/include/Engine/Network/EInterpolate.h
@@ -0,0 +1,20 @@
+#ifndef Events_Interpolate_h__
+#define Events_Interpolate_h__
+
+#include <boost/shared_array.hpp>
+
+#include "Core/EventBroker.h"
+#include "Core/Entity.h"
+
+namespace Events
+{
+
+struct Interpolate : Event
+{
+    EntityID Entity;
+    boost::shared_array<char*> DataArray;
+};
+
+}
+
+#endif
\ No newline at end of file
diff --git a/include/Game/InterpolationSystem.h b/include/Game/InterpolationSystem.h
new file mode 100644
index 00000000..c87ee5a7
--- /dev/null
+++ b/include/Game/InterpolationSystem.h
@@ -0,0 +1,42 @@
+#ifndef Systems_InterpolationSystem_h__
+#define Systems_InterpolationSystem_h__
+
+#include <queue>
+#include <unordered_map>
+#include <boost/shared_array.hpp>
+#include <glm/common.hpp>
+
+#include "Common.h"
+#include "Core/System.h"
+#include "Core/EventBroker.h"
+
+#include "Network/EInterpolate.h"
+
+struct Transform {
+    glm::vec3 Position;
+    glm::vec3 Scale;
+    glm::vec3 Orientation;
+    double interpolationTime;
+};
+
+class InterpolationSystem : public PureSystem
+{
+public:
+    InterpolationSystem(EventBroker* eventbroker)
+        : PureSystem(eventbroker, "Transform")
+    {
+        EVENT_SUBSCRIBE_MEMBER(m_EInterpolate, &InterpolationSystem::OnInterpolate);
+    }
+    ~InterpolationSystem() { }
+
+    virtual void UpdateComponent(World* world, ComponentWrapper& transform, double dt) override;
+private:
+    std::unordered_map<EntityID, std::queue<Transform>> m_InterpolationPoints;
+
+    glm::vec3 vectorInterpolation(glm::vec3 prev, glm::vec3 next, double currentTime);
+
+    EventRelay<InterpolationSystem, Events::Interpolate> m_EInterpolate;
+    bool InterpolationSystem::OnInterpolate(const Events::Interpolate& e);
+};
+
+#endif
diff --git a/src/Game/InterpolationSystem.cpp b/src/Game/InterpolationSystem.cpp
new file mode 100644
index 00000000..d2d81fda
--- /dev/null
+++ b/src/Game/InterpolationSystem.cpp
@@ -0,0 +1,50 @@
+#include "InterpolationSystem.h"
+
+void InterpolationSystem::UpdateComponent(World * world, ComponentWrapper & transform, double dt)
+{
+    if (m_InterpolationPoints[transform.EntityID].size() > 0) {
+        Transform& sTransform = m_InterpolationPoints[transform.EntityID].front();
+        sTransform.interpolationTime += dt;
+        if (sTransform.interpolationTime > 0.05) {
+            double time = std::fmod(sTransform.interpolationTime, 0.05f);
+            m_InterpolationPoints[transform.EntityID].pop();
+            if (m_InterpolationPoints[transform.EntityID].size() <= 0) {
+                return;
+            }
+            sTransform = m_InterpolationPoints[transform.EntityID].front();
+            sTransform.interpolationTime = time;
+        }
+        glm::vec3 nextPosition = sTransform.Position;
+        glm::vec3 currentPosition = static_cast<glm::vec3>(transform["Position"]);
+        transform["Position"] = vectorInterpolation(currentPosition, nextPosition, sTransform.interpolationTime);
+    }
+}
+
+glm::vec3 InterpolationSystem::vectorInterpolation(glm::vec3 prev, glm::vec3 next, double currentTime)
+{
+    glm::vec3 difference = next - prev;
+    glm::vec3 position = difference / 0.05f * static_cast<float>(currentTime);
+    return position;
+}
+
+bool InterpolationSystem::OnInterpolate(const Events::Interpolate & e)
+{
+    Transform transform;
+    int offset = 0;
+    // Read the data
+    memcpy(&transform.Position, e.DataArray.get() + offset, sizeof(glm::vec3));
+    offset += sizeof(glm::vec3);
+    memcpy(&transform.Orientation, e.DataArray.get() + offset, sizeof(glm::vec3));
+    offset += sizeof(glm::vec3);
+    memcpy(&transform.Scale, e.DataArray.get() + offset, sizeof(glm::vec3));
+
+    // Check if queue already exists
+    if (m_InterpolationPoints.find(e.Entity) != m_InterpolationPoints.end()) { // Did exist, push to queue
+        m_InterpolationPoints[e.Entity].push(transform);
+    } else { // Did not exist, create queue
+        std::queue<Transform> transformQueue;
+        transformQueue.push(transform);
+        m_InterpolationPoints[e.Entity] = transformQueue;
+    }
+    return false;
+}