From cc17c10e1f1a1ce7c6aabde0ef11922f62bcbbd9 Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 21:16:55 +0200
Subject: [PATCH 1/7] adding really nice explosion (in simple renderer)

---
 game/game_window.hpp            | 17 +++++++++++-
 game/state/explosion.hpp        | 23 ++++++++--------
 game/state/missile.cpp          |  4 +--
 game/state/missile.hpp          | 21 ++++++---------
 game/state/missile_hit_type.hpp | 19 +++++++++++++
 game/state/state.cpp            | 48 ++++++++++++++++++++++++++-------
 game/state/state.hpp            | 16 +++++++----
 7 files changed, 106 insertions(+), 42 deletions(-)
 create mode 100644 game/state/missile_hit_type.hpp

diff --git a/game/game_window.hpp b/game/game_window.hpp
index 8bd7c4f..9a2d99d 100644
--- a/game/game_window.hpp
+++ b/game/game_window.hpp
@@ -11,6 +11,7 @@
 #include "state/player.hpp"
 #include "state/planet.hpp"
 #include "state/ship.hpp"
+#include "state/explosion.hpp"
 
 class GameWindow : public endofthejedi::GLWindow {
 private:
@@ -46,6 +47,10 @@ protected:
             drawTrace(trace);
         }
 
+        for (const game::Explosion *explosion : m_game.state()->explosions) {
+            drawExplosion(explosion);
+        }
+
         for (const game::Ship *ship : m_game.state()->ships) {
             drawShip(ship->position);
         }
@@ -78,7 +83,6 @@ protected:
     }
 
     void drawMissile(const glm::vec2 &pos)
-
     {
         glm::vec3 color = glm::vec3(1.0, 1.0, 0.3);
         m_renderer.drawCircle(pos.x, pos.y, 0.01, color.x, color.y, color.z, 6);
@@ -92,6 +96,17 @@ protected:
         }
     }
 
+    void drawExplosion(const game::Explosion *explosion)
+    {
+        // TODO: transparent
+        // TODO: with glow in the middle
+        float r = explosion->maxRadius * (explosion->age / explosion->maxAge);
+
+        // TODO: transparency?
+        glm::vec3 color = glm::vec3(1.0, 0.9, 0.1);
+        m_renderer.drawCircle(explosion->position.x, explosion->position.y, r, color.x, color.y, color.z, 64);
+    }
+
 public:
     GameWindow(unsigned int width, unsigned int height)
         : endofthejedi::GLWindow(width, height) {}
diff --git a/game/state/explosion.hpp b/game/state/explosion.hpp
index 66c234f..32169eb 100644
--- a/game/state/explosion.hpp
+++ b/game/state/explosion.hpp
@@ -2,31 +2,32 @@
 
 #include <glm/vec2.hpp>
 
+#include "util.hpp"
+
+#include "missile_hit_type.hpp"
+
 namespace game {
     /**
      * Explosion: just an effect which looks good.
      */
     class Explosion {
     public:
-        enum class Kind {
-            MissileExplodesInSpace, // missile explode in free space
-            MissileAgainstPlanet,   // explosion of missile when it hits a planet
-            MissileAgainstShip      // bigger explosion: missile hits a ship which explodes with it
-        };
-
-        Explosion(const glm::vec2 &pos, Kind kind, float maxAge=1.0)
-            : position(pos), kind(kind), age(0.0), maxAge(maxAge)
+        Explosion(const glm::vec2 &pos, Hit hit, float maxAge=1.0)
+            : hit(hit)
+            , position(pos)
+            , age(0.0)
+            , maxAge(maxAge * (1.0 + 0.1*util::randf_0_1()))
+            , maxRadius(0.05)
         {
         }
 
-        const Kind      kind;     // kind of the explosion
+        const Hit       hit;      // kind of the explosion depends on the hit type
         const glm::vec2 position; // position where it starts
         float           age;      // age (in seconsd) of the explosion
 
         // age (in seconds) when the explosion is not visible
         // anymore and will disappear afterwards
         const float     maxAge;
+        const float     maxRadius; // current radius depends on time.
     };
 }
-
-#endif
diff --git a/game/state/missile.cpp b/game/state/missile.cpp
index b789b5f..08a04b7 100644
--- a/game/state/missile.cpp
+++ b/game/state/missile.cpp
@@ -49,7 +49,7 @@ namespace game {
             if (dist <= planet->radius) {
                 // TODO: collect all hits and return the first one only
                 // TODO: find exact hit position!
-                return Missile::Event(position, Missile::HitObject::HitPlanet);
+                return Missile::Event(position, Hit::Planet);
             }
 
             dist *= 20.0;
@@ -77,7 +77,7 @@ namespace game {
         // check if distance to center of the universe is getting too big
         float distToCenter = glm::length(position);
         if (distToCenter > state->maxMissileDistance()) {
-            return Missile::Event(position, Missile::HitObject::LeftUniverse);
+            return Missile::Event(position, Hit::BorderOfUniverse);
         }
 
         return Missile::Event(position);
diff --git a/game/state/missile.hpp b/game/state/missile.hpp
index c68706d..2763fe7 100644
--- a/game/state/missile.hpp
+++ b/game/state/missile.hpp
@@ -3,6 +3,8 @@
 #include <glm/vec2.hpp>
 #include <glm/vec3.hpp>
 
+#include "missile_hit_type.hpp"
+
 namespace game {
     class State;
     class Ship;
@@ -15,36 +17,29 @@ namespace game {
     // trace then belongs to the player.
     class Missile {
     public:
-        enum class HitObject {
-            Nothing,
-            HitPlayer,
-            HitPlanet,
-            // HitMissile,
-            LeftUniverse
-        };
 
         // missile advances to pos. if hit != Nothing, it hits something and
         // stops existing afterwards.
         class Event {
         public:
-            Event(const glm::vec2 &pos) : Event(pos, HitObject::Nothing)
+            Event(const glm::vec2 &pos) : Event(pos, Hit::Nothing)
             {
             }
 
-            Event(const glm::vec2 &pos, HitObject hit)
-                : hit(hit), pos(pos)
+            Event(const glm::vec2 &pos, Hit hit)
+                : hit(hit), position(pos)
             {
             }
 
             Event(const glm::vec2 &pos, int playerIdKiller, int playerIdVictim)
-                : Event(pos, HitObject::HitPlayer)
+                : Event(pos, Hit::Ship)
             {
                   this->playerIdKiller = playerIdKiller;
                   this->playerIdVictim = playerIdVictim;
             }
 
-            HitObject hit;
-            glm::vec2 pos;
+            Hit       hit;
+            glm::vec2 position;
 
             int playerIdKiller;
             int playerIdVictim;
diff --git a/game/state/missile_hit_type.hpp b/game/state/missile_hit_type.hpp
new file mode 100644
index 0000000..04f1af3
--- /dev/null
+++ b/game/state/missile_hit_type.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+namespace game {
+    /*
+     * A missile can hit different objects the type says which one.
+     * Used in various places so extra file for this.
+     */
+    enum class Hit {
+        Nothing,
+        Ship,
+        Planet,
+
+        // TODO could be needed for really fancy explosions because
+        // this is cool and should noh happen very often
+        // AgainstMissile,
+
+        BorderOfUniverse
+    };
+}
diff --git a/game/state/state.cpp b/game/state/state.cpp
index bc39594..d84364d 100644
--- a/game/state/state.cpp
+++ b/game/state/state.cpp
@@ -6,6 +6,7 @@
 #include <glm/vec3.hpp>
 #include <glm/gtx/norm.hpp>
 
+#include "missile_hit_type.hpp"
 #include "object.hpp"
 #include "missile.hpp"
 #include "player.hpp"
@@ -13,6 +14,7 @@
 #include "ship.hpp"
 #include "commands.hpp"
 #include "trace.hpp"
+#include "explosion.hpp"
 
 #include "util.hpp"
 
@@ -162,26 +164,25 @@ namespace game {
                 //std::cout<<"missile: " << (long unsigned int) missile << std::endl;
                 const Missile::Event evt = missile->advance(this, dt);
 
-                missile->trace->addPointFromMissile();
+                const bool isHit = (evt.hit != Hit::Nothing);
 
-                // TODO:
-                // spawn just if the path differs
+                missile->trace->addPointFromMissile(isHit); // force point if missile gets destroyed a
 
-                if (evt.hit == Missile::HitObject::Nothing) {
+                if (!isHit) {
                     i++;
 
                 } else {
                     switch(evt.hit) {
-                        case Missile::HitObject::HitPlanet:
+                        case Hit::Planet:
                             //std::cout<<"hit Planet" << std::endl;
                             break;
 
-                        case Missile::HitObject::HitPlayer:
+                        case Hit::Ship:
                             //std::cout<<"hit Player" << std::endl;
                             playerKillsPlayer(playerForId(evt.playerIdKiller), playerForId(evt.playerIdVictim));
                             break;
 
-                        case Missile::HitObject::LeftUniverse:
+                        case Hit::BorderOfUniverse:
                             //std::cout<<"missile left the universe." << std::endl;
                             break;
 
@@ -189,6 +190,8 @@ namespace game {
                             break;
                     }
 
+                    addExplosionFromHit(&evt);
+
                     player->missiles.erase(player->missiles.begin() + i);
                     delete(missile);
                     //std::cout<<std::endl;
@@ -200,16 +203,32 @@ namespace game {
         }
     }
 
+    void State::advanceExplosions(float dt)
+    {
+        size_t i=0;
+        while(i < explosions.size()) {
+            Explosion *explosion = explosions[i];
+            explosion->age += dt;
+            if (explosion->age >= explosion->maxAge) {
+                delete(explosion);
+                explosions.erase(explosions.begin()+i);
+                continue;
+            }
+
+            i++;
+        }
+    }
+
     void State::advance(float dt)
     {
-        //std::cout<<"advance ship spawns" << std::endl;
         advancePlayerShipSpawns(dt);
 
-        //std::cout<<"advance commands" << std::endl;
+        advanceExplosions(dt);
+
         advancePlayerCommands(dt);
 
-        //std::cout<<"advance missiles" << std::endl;
         advancePlayerMissiles(dt);
+
     }
 
     Player *State::playerForId(int playerId)
@@ -270,4 +289,13 @@ namespace game {
     {
         traces.push_back(trace);
     }
+
+    void State::addExplosionFromHit(const Missile::Event *evt)
+    {
+        if (evt->hit == Hit::Nothing || evt->hit == Hit::BorderOfUniverse) {
+            return;
+        }
+
+        explosions.push_back(new Explosion(evt->position, evt->hit));
+    }
 }
diff --git a/game/state/state.hpp b/game/state/state.hpp
index 0df4313..3fa7781 100644
--- a/game/state/state.hpp
+++ b/game/state/state.hpp
@@ -7,14 +7,16 @@
 
 #include <glm/vec2.hpp>
 
+#include "missile.hpp"
+
 namespace game {
     // forward declarations
     class Command;
-    class Missile;
     class Player;
     class Planet;
     class Ship;
     class Trace;
+    class Explosion;
 
     class State {
     public:
@@ -61,10 +63,11 @@ namespace game {
 
         // Game items which should be rendered are here:
         // (access missiles by iterating over player's missiles attribute)
-        std::vector<Planet*>  planets;
-        std::vector<Ship*>    ships;
-        std::vector<Player*>  players;
-        std::vector<Trace*>   traces;
+        std::vector<Planet*>    planets;
+        std::vector<Ship*>      ships;
+        std::vector<Player*>    players;
+        std::vector<Trace*>     traces;
+        std::vector<Explosion*> explosions;
 
     private:
         /*************************************************************************/
@@ -73,6 +76,9 @@ namespace game {
 
         void playerKillsPlayer(Player *killer, Player *victim);
 
+        void addExplosionFromHit(const Missile::Event *evt);
+
+        void advanceExplosions(float dt);
         void advancePlayerShipSpawns(float dt);
         void advancePlayerCommands(float dt);
         void advancePlayerMissiles(float dt);

From 67f43de22c50635117763b109618a0dac0e71c2d Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 22:35:16 +0200
Subject: [PATCH 2/7] added a few more commands.

---
 game/game.cpp           | 17 ++--------
 game/state/commands.cpp | 40 ++++++++++++++++++++---
 game/state/commands.hpp | 71 ++++++++++++++++++++++++++++++++++++++---
 game/state/player.hpp   |  5 ++-
 game/state/state.cpp    | 16 +++++++++-
 game/state/state.hpp    | 13 ++++++++
 game/state/trace.cpp    |  5 +++
 game/state/trace.hpp    |  4 +++
 8 files changed, 147 insertions(+), 24 deletions(-)

diff --git a/game/game.cpp b/game/game.cpp
index 38fcc0c..a6b96d9 100644
--- a/game/game.cpp
+++ b/game/game.cpp
@@ -9,7 +9,7 @@
 Game::Game()
 {
     // advance simulation with 100 Hz
-    m_time_step = 1.0 / 100.0;
+    m_time_step          = 1.0 / 100.0;
     m_time_for_next_step = 0.0;
 
     m_state = new game::State();
@@ -33,13 +33,9 @@ bool Game::cycle(float dt)
 
         float a = 2.0 * M_PI * util::randf_0_1();
         float speed = 0.005;
-        m_state->players[0]->addCommand(new game::ShootCommand(a, speed));
-    }
 
-#if 1
-    if (dt >= 10.0) {
-        //std::cout<<"time to big: " << dt << std::endl;
-        dt = m_time_step;
+        m_state->players[0]->addCommand(new game::SetSpeedCommand(speed));
+        m_state->players[0]->addCommand(new game::ShootCommand(a));
     }
 
     //std::cout<<"adding dt: " << dt << std::endl;
@@ -57,11 +53,4 @@ bool Game::cycle(float dt)
     //std::cout << m_time_for_next_step << " s remaining time, " << steps << " steps taken." << std::endl;
 
     return true;
-#else
-    (void) dt;
-
-    m_state->advance(dt);
-
-    return true;
-#endif
 }
diff --git a/game/state/commands.cpp b/game/state/commands.cpp
index b84a214..2b82f27 100644
--- a/game/state/commands.cpp
+++ b/game/state/commands.cpp
@@ -10,23 +10,55 @@ namespace game {
         // TODO: idea
         // shoot multiple rockets at once or from different positions after
         // level up / upgrade ...
-        Missile *missile = new Missile(player, player->ship->position, m_angle, m_speed);
+        Missile *missile = new Missile(player, player->ship->position, m_angle, player->speed);
 
         Trace *trace = new Trace(missile);
         missile->trace = trace;
 
-        player->energy -= m_speed;
+        player->energy -= player->speed;
         player->missiles.push_back(missile);
 
         state->addTrace(trace);
     }
 
-    bool ShootCommand::allowed(const Player *player, const State *state) const
+    bool ShootCommand::ready(const Player *player, const State *state) const
     {
         (void) state;
 
         // TODO
-        return player->alive && player->energy >= m_speed;
+        return player->alive && player->energy >= player->speed;
         //return player->alive;
     }
+
+    void ChangeNameCommand::apply(Player *player, State *state) const
+    {
+        // discard if not unique
+        for (const Player *other : state->players) {
+            if (m_name == other->name) {
+                std::cout << "name '" << m_name << "' already given to player #" << other->id << std::endl;
+                return;
+            }
+        }
+
+        player->name = m_name;
+    }
+
+    void SetSpeedCommand::apply(Player *player, State *state) const
+    {
+        (void) state;
+        player->speed = m_speed;
+    }
+
+    void ClearTracesCommand::apply(Player *player, State *state) const
+    {
+        size_t i = 0;
+        while(i < state->traces.size()) {
+            Trace *trace = state->traces[i];
+            if (trace->missile == nullptr && trace->missile->player == player) {
+                state->deleteTrace(trace);
+            } else {
+                i++;
+            }
+        }
+    }
 }
diff --git a/game/state/commands.hpp b/game/state/commands.hpp
index 5c8ff97..4ed914f 100644
--- a/game/state/commands.hpp
+++ b/game/state/commands.hpp
@@ -9,6 +9,10 @@
 #include <iostream>
 
 namespace game {
+    /**
+     * Base class for commands.
+     * must derive from this.
+     */
     class Command {
     public:
         Command()
@@ -19,7 +23,11 @@ namespace game {
         {
         }
 
-        virtual bool allowed(const Player *player, const State *state) const
+        // check whether the command is ready to execute.
+        // if not, wait.
+        // note: stuff like for admin should be done in execute() to discard the
+        // command and not block the queue.
+        virtual bool ready(const Player *player, const State *state) const
         {
             (void) player;
             (void) state;
@@ -38,19 +46,74 @@ namespace game {
         virtual std::string name() const { return "<unnamed>"; }
     };
 
+    /**********************************************************************/
+    /* Implemented commands */
+    /**********************************************************************/
+
+    /*
+     * Shoot at angle and optional speed.
+     * TODO
+     */
     class ShootCommand : public Command {
     public:
-        ShootCommand(float angle, float speed) : m_angle(angle), m_speed(speed)
+        ShootCommand(float angle) : m_angle(angle)
         {
         }
 
         std::string name() const { return "<shoot>"; }
 
-        void apply(        Player *player,       State *state) const;
-        bool allowed(const Player *player, const State *state) const;
+        void apply(      Player *player,       State *state) const;
+        bool ready(const Player *player, const State *state) const;
 
     private:
         float m_angle;
+    };
+
+    /**
+     * Change the name of the player if it will be uniuqe.
+     */
+    class ChangeNameCommand : public Command {
+    public:
+        ChangeNameCommand(const std::string &name) : m_name(name)
+        {
+        }
+
+        std::string name() const { return "<change name>"; }
+
+        void apply(Player *player, State *state) const;
+
+    private:
+        std::string m_name;
+    };
+
+    /**
+     * clear all traces of this player that are done
+     */
+    class ClearTracesCommand : public Command {
+    public:
+        ClearTracesCommand()
+        {
+        }
+
+        std::string name() const { return "<clear traces>"; }
+
+        void apply(Player *player, State *state) const;
+    };
+
+    /**
+     * Set default speed of next shots for this player.
+     */
+    class SetSpeedCommand : public Command {
+    public:
+        SetSpeedCommand(float speed) : m_speed(speed)
+        {
+        }
+
+        std::string name() const { return "<set speed>"; }
+
+        void apply(Player *player, State *state) const;
+
+    private:
         float m_speed;
     };
 }
diff --git a/game/state/player.hpp b/game/state/player.hpp
index 199a411..3a6aeb4 100644
--- a/game/state/player.hpp
+++ b/game/state/player.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <string>
 #include <deque>
 #include <vector>
 
@@ -15,12 +16,14 @@ namespace game {
     public:
         int        id;
         bool       alive;
+        float      speed;
         float      energy;
         float      deadTimeCounter;
         Ship      *ship;
+        std::string name;
         std::vector<Missile*> missiles;
 
-        Player(int id) : id(id), alive(true), energy(0.0), ship(nullptr)
+        Player(int id) : id(id), alive(true), speed(0.01), energy(0.0), ship(nullptr), name("<unnamed>")
         {
         }
 
diff --git a/game/state/state.cpp b/game/state/state.cpp
index d84364d..71572e6 100644
--- a/game/state/state.cpp
+++ b/game/state/state.cpp
@@ -108,7 +108,7 @@ namespace game {
             // try to execute as much queued commands as possible.
             while (player->hasCommandInQueue()) {
                 Command *command = player->peekCommand();
-                if (!command->allowed(player, this)) {
+                if (!command->ready(player, this)) {
                     break;
                 }
 
@@ -290,6 +290,20 @@ namespace game {
         traces.push_back(trace);
     }
 
+    void State::deleteTrace(Trace *trace)
+    {
+        // TODO: if traces of running missile is deleted it is dangerous
+
+        size_t i = 0;
+        while(i < traces.size()) {
+            if (traces[i] == trace) {
+                delete(trace);
+                traces.erase(traces.begin()+i);
+                break;
+            }
+        }
+    }
+
     void State::addExplosionFromHit(const Missile::Event *evt)
     {
         if (evt->hit == Hit::Nothing || evt->hit == Hit::BorderOfUniverse) {
diff --git a/game/state/state.hpp b/game/state/state.hpp
index 3fa7781..42d0659 100644
--- a/game/state/state.hpp
+++ b/game/state/state.hpp
@@ -9,6 +9,18 @@
 
 #include "missile.hpp"
 
+// TODO:
+// give points for equipment / better weapons / more energy when:
+// - player discovers the universe
+//
+// - the shot which made a kill was much longer than the direkt line between
+//   player and his target
+//
+// - add wormholes
+// - add blackholes
+// - shoot through suns which add a fire mantle to the rocket to make it more
+//   thick and dangerous but it gets destroyed after some time.
+
 namespace game {
     // forward declarations
     class Command;
@@ -56,6 +68,7 @@ namespace game {
 
         // add a trace to the list of traces.
         void addTrace(Trace *trace);
+        void deleteTrace(Trace *trace);
 
         /*************************************************************************/
         /* Rendering */
diff --git a/game/state/trace.cpp b/game/state/trace.cpp
index 4d93d2c..392076e 100644
--- a/game/state/trace.cpp
+++ b/game/state/trace.cpp
@@ -24,4 +24,9 @@ namespace game {
             points.push_back(TracePoint(missile));
         }
     }
+
+    void Trace::finish()
+    {
+        missile = nullptr;
+    }
 }
diff --git a/game/state/trace.hpp b/game/state/trace.hpp
index ab33b2f..7af85dc 100644
--- a/game/state/trace.hpp
+++ b/game/state/trace.hpp
@@ -21,6 +21,10 @@ namespace game {
             // the missile) in case the fidelityCounter would skip the current position.
             void addPointFromMissile(bool forceAdd=false);
 
+            // call this to mark the trace as finish and disconnect it from the
+            // missile.
+            void finish();
+
             // TODO: add extendLastPointToPosition() method for saving points /
             // optimization later on
 

From eaba518ce4ef0797419ed7c70128bebf4a5e392d Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 23:07:11 +0200
Subject: [PATCH 3/7] fiexd cleartraces command.

---
 game/game.cpp           | 19 +++++++++++++++++++
 game/state/commands.cpp |  9 +++++++--
 game/state/state.cpp    | 38 +++++++++++++++++++++++++++++---------
 game/state/state.hpp    |  5 ++++-
 game/state/trace.cpp    | 14 +++++++++++++-
 game/state/trace.hpp    | 11 +++++++++--
 6 files changed, 81 insertions(+), 15 deletions(-)

diff --git a/game/game.cpp b/game/game.cpp
index a6b96d9..128cdca 100644
--- a/game/game.cpp
+++ b/game/game.cpp
@@ -24,8 +24,20 @@ Game::Game()
 
 bool Game::cycle(float dt)
 {
+    static float total = 0.0;
     static float acc = 0.0;
+
+    //if (total == 0.0) {
+    //    float speed = 0.005;
+    //    m_state->players[0]->addCommand(new game::SetSpeedCommand(speed));
+    //    for (int i=0; i<100; i++) {
+    //        float a = 2.0 * M_PI * util::randf_0_1();
+    //        m_state->players[0]->addCommand(new game::ShootCommand(a));
+    //    }
+    //}
+
     acc += dt;
+    total += dt;
 
     float spawnInterval = 0.1;
     while(acc > spawnInterval) {
@@ -36,6 +48,13 @@ bool Game::cycle(float dt)
 
         m_state->players[0]->addCommand(new game::SetSpeedCommand(speed));
         m_state->players[0]->addCommand(new game::ShootCommand(a));
+
+        //static bool done = false;
+        //if (total >= 10.0 && !done) {
+        //    done = true;
+
+        //    m_state->players[0]->addCommand(new game::ClearTracesCommand());
+        //}
     }
 
     //std::cout<<"adding dt: " << dt << std::endl;
diff --git a/game/state/commands.cpp b/game/state/commands.cpp
index 2b82f27..5dac8e0 100644
--- a/game/state/commands.cpp
+++ b/game/state/commands.cpp
@@ -2,6 +2,8 @@
 
 #include "trace.hpp"
 
+#include <iostream>
+
 namespace game {
     void ShootCommand::apply(Player *player, State *state) const
     {
@@ -51,11 +53,14 @@ namespace game {
 
     void ClearTracesCommand::apply(Player *player, State *state) const
     {
+        std::cout<<"clearing traces!!!" << std::endl;
+
         size_t i = 0;
         while(i < state->traces.size()) {
             Trace *trace = state->traces[i];
-            if (trace->missile == nullptr && trace->missile->player == player) {
-                state->deleteTrace(trace);
+            if (trace->missile == nullptr && trace->player == player) {
+                state->deleteTrace(i);
+
             } else {
                 i++;
             }
diff --git a/game/state/state.cpp b/game/state/state.cpp
index 71572e6..e76e23e 100644
--- a/game/state/state.cpp
+++ b/game/state/state.cpp
@@ -145,12 +145,9 @@ namespace game {
 
         // TODO
         // add points
-        //
+
         // TODO
         // message
-        //
-        // TODO
-        // respawn timer
     }
 
     void State::advancePlayerMissiles(float dt)
@@ -166,7 +163,9 @@ namespace game {
 
                 const bool isHit = (evt.hit != Hit::Nothing);
 
-                missile->trace->addPointFromMissile(isHit); // force point if missile gets destroyed a
+                if (missile->trace != nullptr) {
+                    missile->trace->addPointFromMissile(isHit); // force point if missile gets destroyed a
+                }
 
                 if (!isHit) {
                     i++;
@@ -192,6 +191,10 @@ namespace game {
 
                     addExplosionFromHit(&evt);
 
+                    if (missile->trace != nullptr) {
+                        missile->trace->finish();
+                    }
+
                     player->missiles.erase(player->missiles.begin() + i);
                     delete(missile);
                     //std::cout<<std::endl;
@@ -290,15 +293,32 @@ namespace game {
         traces.push_back(trace);
     }
 
+    void State::deleteTrace(size_t index)
+    {
+        if (index >= traces.size()) {
+            std::cerr << "can't find trace with invalid index " << index << std::endl;
+            return;
+        }
+
+        Trace *trace = traces[index];
+
+        //std::cout<<"removing a trace" << std::endl;
+        if (trace->missile != nullptr) {
+            // delete backlink.
+            // XXX: there's a missile without a trace now.
+            trace->missile->trace = nullptr;
+        }
+
+        traces.erase(traces.begin() + index);
+        delete(trace);
+    }
+
     void State::deleteTrace(Trace *trace)
     {
-        // TODO: if traces of running missile is deleted it is dangerous
-
         size_t i = 0;
         while(i < traces.size()) {
             if (traces[i] == trace) {
-                delete(trace);
-                traces.erase(traces.begin()+i);
+                deleteTrace(i);
                 break;
             }
         }
diff --git a/game/state/state.hpp b/game/state/state.hpp
index 42d0659..7128966 100644
--- a/game/state/state.hpp
+++ b/game/state/state.hpp
@@ -68,7 +68,10 @@ namespace game {
 
         // add a trace to the list of traces.
         void addTrace(Trace *trace);
-        void deleteTrace(Trace *trace);
+
+        // delete traces with this command
+        void deleteTrace(Trace *trace); // using a pointer
+        void deleteTrace(size_t index); // using an index
 
         /*************************************************************************/
         /* Rendering */
diff --git a/game/state/trace.cpp b/game/state/trace.cpp
index 392076e..0b51695 100644
--- a/game/state/trace.cpp
+++ b/game/state/trace.cpp
@@ -4,6 +4,8 @@
 
 #include "missile.hpp"
 
+#include <iostream>
+
 namespace game {
     Trace::TracePoint::TracePoint(const Missile *missile)
         : position(missile->position)
@@ -11,7 +13,16 @@ namespace game {
     {
     }
 
-    Trace::Trace(const Missile *missile) : missile(missile), fidelityCounter(0)
+    Trace::~Trace()
+    {
+        //std::cout<<"~Trace()" << std::endl;
+    }
+
+    Trace::Trace(Missile *missile)
+        : missile(missile)
+        , player(missile->player)
+        , fidelityCounter(0)
+        , age(0.0)
     {
         points.push_back(TracePoint(missile));
     }
@@ -27,6 +38,7 @@ namespace game {
 
     void Trace::finish()
     {
+        //std::cout<<"trace finished now!" << std::endl;
         missile = nullptr;
     }
 }
diff --git a/game/state/trace.hpp b/game/state/trace.hpp
index 7af85dc..2b4f4f0 100644
--- a/game/state/trace.hpp
+++ b/game/state/trace.hpp
@@ -5,6 +5,7 @@
 
 namespace game {
     class Missile;
+    class Player;
 
     /*
      * Trace of a missile through the space.
@@ -12,7 +13,8 @@ namespace game {
      */
     class Trace {
         public:
-            Trace(const Missile *missile);
+            Trace(Missile *missile);
+            ~Trace();
 
             // Add the current position of the missile as a new point on the
             // trace.
@@ -39,11 +41,16 @@ namespace game {
             };
 
             std::vector<TracePoint> points;
-            const Missile *missile; // missile which creates this path.
+            Missile                *missile; // missile which creates this path.
+            Player                 *player;
 
             // counter which is incremented each time addPointFromMissile() is called.
             // when reaching a certain value the point is saved for
             // optimization.
             int fidelityCounter;
+
+            // age of the trace. if too old, it can be removed to save
+            // space/power
+            float age;
     };
 }

From e1eb158f3f1e59856123dc2a5bbd5079bce0b756 Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 23:16:25 +0200
Subject: [PATCH 4/7] small fix

---
 game/game.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/game/game.cpp b/game/game.cpp
index 128cdca..b0b590b 100644
--- a/game/game.cpp
+++ b/game/game.cpp
@@ -8,7 +8,7 @@
 
 Game::Game()
 {
-    // advance simulation with 100 Hz
+    // advance simulation in fixed steps with 100 Hz
     m_time_step          = 1.0 / 100.0;
     m_time_for_next_step = 0.0;
 
@@ -24,6 +24,9 @@ Game::Game()
 
 bool Game::cycle(float dt)
 {
+#if 1
+    // XXX the following is just testing code to do things
+
     static float total = 0.0;
     static float acc = 0.0;
 
@@ -36,18 +39,18 @@ bool Game::cycle(float dt)
     //    }
     //}
 
-    acc += dt;
+    acc   += dt;
     total += dt;
 
     float spawnInterval = 0.1;
     while(acc > spawnInterval) {
         acc -= spawnInterval;
 
-        float a = 2.0 * M_PI * util::randf_0_1();
+        float angle = 2.0 * M_PI * util::randf_0_1();
         float speed = 0.005;
 
         m_state->players[0]->addCommand(new game::SetSpeedCommand(speed));
-        m_state->players[0]->addCommand(new game::ShootCommand(a));
+        m_state->players[0]->addCommand(new game::ShootCommand(angle));
 
         //static bool done = false;
         //if (total >= 10.0 && !done) {
@@ -56,6 +59,7 @@ bool Game::cycle(float dt)
         //    m_state->players[0]->addCommand(new game::ClearTracesCommand());
         //}
     }
+#endif
 
     //std::cout<<"adding dt: " << dt << std::endl;
     m_time_for_next_step += dt;

From 1b3702db8af3055a18f0b85ac9f2985697a5d87d Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 23:29:26 +0200
Subject: [PATCH 5/7] added sun

---
 game/state/planet.hpp | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/game/state/planet.hpp b/game/state/planet.hpp
index 0407683..38f02b6 100644
--- a/game/state/planet.hpp
+++ b/game/state/planet.hpp
@@ -2,11 +2,38 @@
 
 #include "object.hpp"
 
+#include <cstdlib>
+
 namespace game {
     class Planet : public Object {
     public:
-        Planet(const glm::vec2 &pos, float r) : Object(pos, r)
+        /**
+         * Planets are build out of one material.
+         * TODO: support mixture or multiple material per planet.
+         */
+        enum class Material {
+            Rock,
+            Metal,
+            Sand,
+            Gas,
+            Ice,
+            Water,
+            Sun
+        };
+
+        Planet(const glm::vec2 &pos, float r) : Planet(pos, r, Material::Rock)
         {
         }
+
+        Planet(const glm::vec2 &pos, float r, Material mat)
+            : Object(pos, r)
+            , material(mat)
+            , seed(rand())
+        {
+        }
+
+        // nice for rendering attributes
+        Material material;
+        int      seed;
     };
 }

From bfa7be68a99825b0badcd45edc2c7471fa25ee26 Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Tue, 27 Sep 2016 23:50:44 +0200
Subject: [PATCH 6/7] added not complete take over playeer command.

---
 game/state/commands.cpp | 14 ++++++++++++++
 game/state/commands.hpp | 21 +++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/game/state/commands.cpp b/game/state/commands.cpp
index 5dac8e0..1a64d89 100644
--- a/game/state/commands.cpp
+++ b/game/state/commands.cpp
@@ -66,4 +66,18 @@ namespace game {
             }
         }
     }
+
+#if 0
+    bool TakeOverPlayerCommand::ready(const Player *player, const State *state) const
+    {
+        (void) state;
+        return state->havePlayerGrantFor(player->id, m_otherPlayerId);
+    }
+
+    void TakeOverPlayerCommand::apply(Player *player, State *state) const
+    {
+        if (
+        state->playerGrant(player->id, m_otherPlayerId);
+    }
+#endif
 }
diff --git a/game/state/commands.hpp b/game/state/commands.hpp
index 4ed914f..dd88c0c 100644
--- a/game/state/commands.hpp
+++ b/game/state/commands.hpp
@@ -116,4 +116,25 @@ namespace game {
     private:
         float m_speed;
     };
+
+#if 0
+    /**
+     * Take over a session for a player that left.
+     * An admin must confirm this command.
+     */
+    class TakeOverPlayerCommand : public Command {
+    public:
+        TakeOverPlayerCommand(int otherPlayerId) : m_otherPlayerId(otherPlayerId)
+        {
+        }
+
+        std::string name() const { return "<take over player>"; }
+
+        void apply(      Player *player,       State *state) const;
+        bool ready(const Player *player, const State *state) const;
+
+    private:
+        int m_otherPlayerId;
+    };
+#endif
 }

From 1e90a1c9c8f8ca3cf7e2e760d1b499f45ef2544a Mon Sep 17 00:00:00 2001
From: Andreas Ortmann <ortmann@finf.uni-hannover.de>
Date: Wed, 28 Sep 2016 00:13:03 +0200
Subject: [PATCH 7/7] adding small stuff to limit traces

---
 game/state/missile.cpp |  2 +-
 game/state/missile.hpp | 12 +++++++++++-
 game/state/planet.hpp  | 11 ++++++-----
 game/state/state.cpp   | 13 ++++++++++++-
 game/state/state.hpp   |  1 +
 5 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/game/state/missile.cpp b/game/state/missile.cpp
index 08a04b7..cbc3e58 100644
--- a/game/state/missile.cpp
+++ b/game/state/missile.cpp
@@ -49,7 +49,7 @@ namespace game {
             if (dist <= planet->radius) {
                 // TODO: collect all hits and return the first one only
                 // TODO: find exact hit position!
-                return Missile::Event(position, Hit::Planet);
+                return Missile::Event(position, planet->id);
             }
 
             dist *= 20.0;
diff --git a/game/state/missile.hpp b/game/state/missile.hpp
index 2763fe7..c7aa1df 100644
--- a/game/state/missile.hpp
+++ b/game/state/missile.hpp
@@ -22,7 +22,8 @@ namespace game {
         // stops existing afterwards.
         class Event {
         public:
-            Event(const glm::vec2 &pos) : Event(pos, Hit::Nothing)
+            Event(const glm::vec2 &pos)
+                : Event(pos, Hit::Nothing)
             {
             }
 
@@ -31,6 +32,11 @@ namespace game {
             {
             }
 
+            Event(const glm::vec2 &pos, int planetId) : Event(pos, Hit::Planet)
+            {
+                this->planetId = planetId;
+            }
+
             Event(const glm::vec2 &pos, int playerIdKiller, int playerIdVictim)
                 : Event(pos, Hit::Ship)
             {
@@ -41,8 +47,12 @@ namespace game {
             Hit       hit;
             glm::vec2 position;
 
+            // if a player was hit, these are valid.
             int playerIdKiller;
             int playerIdVictim;
+
+            // if a planet was hit, this is valid
+            int planetId;
         };
 
         Missile(Player *player, const glm::vec2 &pos, float angle, float speed);
diff --git a/game/state/planet.hpp b/game/state/planet.hpp
index 38f02b6..e6ff6e7 100644
--- a/game/state/planet.hpp
+++ b/game/state/planet.hpp
@@ -21,19 +21,20 @@ namespace game {
             Sun
         };
 
-        Planet(const glm::vec2 &pos, float r) : Planet(pos, r, Material::Rock)
+        Planet(const glm::vec2 &pos, int id, float r) : Planet(pos, id, r, Material::Rock)
         {
         }
 
-        Planet(const glm::vec2 &pos, float r, Material mat)
+        Planet(const glm::vec2 &pos, int id, float r, Material mat)
             : Object(pos, r)
+            , id(id)
             , material(mat)
             , seed(rand())
         {
         }
 
-        // nice for rendering attributes
-        Material material;
-        int      seed;
+        int      id;
+        Material material; // for rendering and physics (can fly through sun and outer gas planets)
+        int      seed;     // just for rendering variation
     };
 }
diff --git a/game/state/state.cpp b/game/state/state.cpp
index e76e23e..fd76907 100644
--- a/game/state/state.cpp
+++ b/game/state/state.cpp
@@ -25,6 +25,7 @@ namespace game {
         m_maxMissileDistance = 2.0;
         m_playerRespawnTime  = 2.0;
         m_defaultEnergy      = 10.0;
+        m_maxNumTraces       = 10;
 
         bool planetsOnCircle = false;
 
@@ -45,7 +46,7 @@ namespace game {
                 }
             } while(glm::length(pos) < 0.2 && tries++ < 1000);
 
-            planets.push_back(new Planet(pos, 0.03 + 0.07*util::randf_0_1()));
+            planets.push_back(new Planet(pos, i, 0.03 + 0.07*util::randf_0_1()));
         }
     }
 
@@ -290,6 +291,16 @@ namespace game {
 
     void State::addTrace(Trace *trace)
     {
+        //int count = 0;
+        //for (Trace *old : traces) {
+        //    if (old->playerId == trace->playerId) {
+        //        count++;
+        //    }
+        //}
+
+        //if (count > m_maxNumTraces) {
+        //}
+
         traces.push_back(trace);
     }
 
diff --git a/game/state/state.hpp b/game/state/state.hpp
index 7128966..88718cb 100644
--- a/game/state/state.hpp
+++ b/game/state/state.hpp
@@ -111,5 +111,6 @@ namespace game {
         float m_playerRespawnTime;
         float m_shipRadius;
         float m_defaultEnergy;
+        int   m_maxNumTraces;
     };
 };