adding event meachinsm for game items that change and sound support.

game/CMakeLists.txt

@@ -22,6 +22,10 @@ set(GAME_SRC
     util.cpp
     game.cpp
 
+    # TODO: make optional!
+    sound/sound.cpp
+    sound/sound_effects.cpp
+
     state/object.cpp
     state/explosion.cpp
     state/trace.cpp
@@ -43,4 +47,4 @@ include_directories(${assimp_INCLUDE_DIRS})
 add_executable(game ${GAME_SRC})
 setup_target(game)
 
-target_link_libraries(game X11 epoxy pthread ${assimp_LIBRARIES} assimp)
+target_link_libraries(game X11 epoxy pthread ${assimp_LIBRARIES} assimp -lportaudio -lsndfile)

game/main.cpp

@@ -10,6 +10,9 @@
 #include "network/server.hpp"
 #include "options.hpp"
 
+#include "sound/sound_effects.hpp"
+#include "state/state_update_event.hpp"
+
 #include <sys/time.h>
 
 uint64_t optionsFlags;
@@ -19,6 +22,7 @@ using asio::ip::tcp;
 int main(int argc, char *argv[])
 {
     bool devMode = false;
+    bool soundEnabled = false;
     char port[]="3490";
 
     static struct option long_options[] =
@@ -33,6 +37,7 @@ int main(int argc, char *argv[])
 //        {"delete",  required_argument, 0, 'd'},
           {"autorun", required_argument, 0, 'a'},
           {"port",    required_argument, 0, 'p'},
+          {"sound",   no_argument,       0, 's'},
           {"fps",     no_argument,       0, 'f'},
           {"dev",     no_argument,       0, 'd'},
           {0, 0, 0, 0}
@@ -41,7 +46,7 @@ int main(int argc, char *argv[])
     int option_index = 0;
 
     while(1){
-        char c = getopt_long (argc, argv, "p:fad",
+        char c = getopt_long (argc, argv, "p:fads",
                        long_options, &option_index);
         if (c == -1)
             break;
@@ -51,6 +56,7 @@ int main(int argc, char *argv[])
             case 'f':
                 SET_FLAG(SHOW_FPS,true);
                 break;
+
             case 'd':
                 std::cout<<"enabling developer mode" << std::endl;
                 devMode = true;
@@ -60,6 +66,10 @@ int main(int argc, char *argv[])
                 strcpy(port,optarg);
                 break;
 
+            case 's':
+                soundEnabled = true;
+                break;
+
             case 'a':
                 SET_FLAG(TEST_AUTORUN, true);
                 break;
@@ -75,6 +85,13 @@ int main(int argc, char *argv[])
 
     srand(time(NULL));
 
+    //sound::SoundEffects *sounds = nullptr;
+    if (soundEnabled) {
+        //if (sound::initSound()) {
+            //sounds = new sound::SoundEffects();
+        //}
+    }
+
     Game game;
     game.state()->setDeveloperMode(devMode);
 
@@ -89,6 +106,10 @@ int main(int argc, char *argv[])
     while(window.running()){
         window.poll();
         io_service.poll();
+
+        //if (sounds != nullptr) {
+        //    sounds.advance(game->state());
+        //}
     }
 
     return 0;

game/network/session.hpp

@@ -33,5 +33,5 @@ private:
     char m_rcv_data[max_length];
     game::State* m_state;
     bool m_started = false;
-    int m_pid;
+    size_t m_pid;
 };

game/sound/sound.cpp

@@ -0,0 +1,968 @@
+#include "sound.hpp"
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+
+#include <portaudio.h>
+
+#include "util.hpp"
+
+// for dumping sound
+#include    <sndfile.h>
+
+namespace sound {
+
+    typedef struct {
+        PaStream *stream;
+
+        unsigned int framesPerBuffer;
+        unsigned int sampleRate;
+
+        unsigned int sound_uid_counter;
+
+        // constant
+        unsigned int maxNumSounds;
+
+        // num active sonuds
+        unsigned int highestSoundIndex;
+
+        // pointer to array of sound handles that has this number of active sounds
+        SoundHandle **sounds;
+
+        bool dumping;
+        const char *dump_filename;
+        SNDFILE *outfile;
+        SF_INFO  sfinfo;
+
+        bool init;
+    } SoundContext;
+
+    // singleton so no arguments must be supplied for play() functions etc.
+    static SoundContext context;
+
+    static double startup_time = -1.0;
+    static double global_time = -1.0;;
+
+    static double timestamp_double(void)
+    {
+        struct timeval now;
+        gettimeofday(&now, NULL);
+
+        //printf("%d %d\n", (int) now.tv_sec, (int) now.tv_usec);
+
+        double t = now.tv_sec;
+        t += now.tv_usec / 1000000.0f;
+        //printf("%f\n", t);
+        return t;
+    }
+
+    const char *stringFromEnvelope(enum EnvelopeState envelope)
+    {
+        switch(envelope) {
+            case New:   return "New";
+            case Wait:  return "Wait";
+            case Rise:  return "Rise";
+            case BeginOvershoot: return "BeginOvershoot";
+            case EndOvershoot: return   "EndOvershoot";
+            case Decay: return "Decay";
+            case Hold:  return "Hold";
+            case Done:  return "Done";
+            default: assert(false); return "<error>";
+        }
+    }
+
+    static void checkEnvelopeState(SoundHandle *handle, enum EnvelopeState next)
+    {
+        if (handle == NULL) {
+            return;
+        }
+
+        if (handle->envelope != next) {
+#if 1
+            printf("[sound] global time %4.3f #%d (%s) t=%f %5s -> %5s\n",
+                global_time,
+                handle->uid,
+                handle->name,
+                handle->time,
+                stringFromEnvelope(handle->envelope),
+                stringFromEnvelope(next));
+#endif
+
+            handle->envelope = next;
+        }
+    }
+
+    void stopDumpingWav(void)
+    {
+        if (!context.init || !context.dumping) {
+            return;
+        }
+
+        int err = sf_close(context.outfile);
+        context.outfile = NULL;
+        context.dumping = false;
+
+       if (err < 0) {
+           printf("warning: stop dumping wav returned error: %d\n", err);
+       } else {
+           printf("sucessfully stopped dumping to file %s\n", context.dump_filename);
+       }
+    }
+
+    static bool dumpSamples(float *samples, size_t numSamples)
+    {
+        // TODO: dumping in mono?
+
+        if (!context.init || !context.dumping) {
+            printf("warning: can't dump samples: context not initialized or not currently dumping!\n");
+            return false;
+        }
+
+        sf_writef_float(context.outfile, samples, numSamples);
+        sf_write_sync(context.outfile); // force writing
+
+        return true;
+    }
+
+    bool startDumpingWav(const char *filename)
+    {
+        if (!context.init) {
+            return false;
+        }
+
+        if (context.dumping) {
+            printf("warning: already dumping to %s!\n", context.dump_filename);
+            return false;
+        }
+
+        context.sfinfo.channels = 2;
+        context.sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_FLOAT;
+        context.sfinfo.samplerate = context.sampleRate;
+
+        context.outfile = sf_open(filename, SFM_WRITE, &context.sfinfo);
+
+        if (context.outfile == NULL) {
+            printf("Unable to dump to output file %s.\n", filename);
+            sf_perror(NULL);
+            return false;
+        };
+
+        //printf("start dumping wav to file %s\n", filename);
+        context.dump_filename = filename;
+        context.dumping = true;
+        return true;
+    }
+
+    static float amplitudeForTime(SoundHandle *handle)
+    {
+        //float amplitude = handle->amplitude;
+        float amplitude = 1.0;
+
+        float t = handle->time;
+        if (t < handle->_riseTime) {
+            // linear increase
+            float a = t / handle->_riseTime;
+
+            if (handle->_relativeOvershootTime == 0.0) {
+                checkEnvelopeState(handle, Rise);
+
+            } else {
+                //
+                //           |--overshoot-up-| |-overshoot-down-|
+                //           |-------------overshoot------------|
+                // |-----------------rise-time -----------------|
+
+                // make it raise to full level earlier
+                const float overshoot = 2.0*handle->_relativeOvershootTime;
+
+                a *= 1.0+overshoot;
+
+                // compensate the overshoot during last r/2 time to normal level
+                // (1.0) by inversing slope
+                if (a < 1.0) {
+                    checkEnvelopeState(handle, Rise);
+
+                } else if (a < 1.0 + (overshoot/2.0)) {
+                    checkEnvelopeState(handle, BeginOvershoot);
+
+                } else {
+                    a = 2.0 + overshoot - a;
+                    checkEnvelopeState(handle, EndOvershoot);
+
+                }
+            }
+
+            amplitude *= a;
+            //printf("amplitude rising: %f\n", a);
+
+        } else {
+            t -= handle->_riseTime;
+            if (t < handle->_holdTime) {
+                // stays constant during this time
+                checkEnvelopeState(handle, Hold);
+
+            } else {
+                t -= handle->_holdTime;
+                if (t < handle->_decayTime) {
+                    // linear decrease
+                    float a = 1.0 - (t / handle->_decayTime);
+                    //printf("amplitude decaying : %f\n", a);
+                    amplitude *= a;
+                    checkEnvelopeState(handle, Decay);
+
+                } else {
+                    bool switchToDone = false;
+                    t -= handle->_decayTime;
+                    if (t < handle->_waitTime) {
+                        // still waiting
+                        checkEnvelopeState(handle, Wait);
+
+                    } else if (handle->looping && (handle->_loopCount == -1 || handle->_loopCount > 0)) {
+                        // waited long enough to restart
+                        // TODO: dont waste time! does stuff stay synchronized
+                        // over a long period of time?
+                        //handle->time = 0.0;
+                        handle->time -= handle->_riseTime + handle->_waitTime + handle->_holdTime + handle->_decayTime;
+
+                        if (handle->_loopCount != -1) {
+                            handle->_loopCount--;
+                            //printf("decrement loopCount to %d\n", handle->_loopCount);
+                            if (handle->_loopCount == 0) {
+                                switchToDone = true;
+                            }
+                        }
+                    } else {
+                        switchToDone = true;
+                    }
+
+                    if (switchToDone) {
+                        // zero
+                        checkEnvelopeState(handle, Done);
+                        handle->_done = true;
+                        return 0.0;
+                    }
+                    amplitude = 0.0;
+                }
+            }
+        }
+
+        //int phase = handle->envelope;
+        //printf("%f, %d, %f\n", handle->time, phase, amplitude);
+
+        if (handle->minAmplitude != 0.0) {
+            amplitude = handle->minAmplitude + amplitude/(1.0-handle->minAmplitude);
+        }
+
+        amplitude *= handle->amplitude;
+
+        return amplitude;
+    }
+
+    // TODO: support stereo fully
+
+    // args:
+    // n: n-th last history value
+    static float historyValue(SoundHandle *handle, size_t n)
+    {
+        if (handle == NULL) {
+            return 0.0;
+        }
+        if (handle->history == NULL) {
+            return 0.0;
+        }
+        if (n >= handle->numHistorySamples) {
+            // TODO clear history when looping?
+            // or add zero samples?
+            printf("warning: try to access more history values than saved.\n");
+            return 0.0;
+        }
+
+        return handle->history[2 * ((handle->lastHistorySample+n) % handle->numHistorySamples)];
+    }
+
+    void saveHistoryValue(SoundHandle *handle, float v)
+    {
+        if (handle == NULL || handle->history == NULL) {
+            return;
+        }
+
+        handle->history[2*handle->lastHistorySample] = v;
+        handle->lastHistorySample = (handle->lastHistorySample+1) % handle->numHistorySamples;
+    }
+
+    float sumHistory(SoundHandle *handle, float initialWeight, float v)
+    {
+        float result = initialWeight * v;
+        float totalWeight = initialWeight;
+
+        size_t i;
+        for (i=0; i<handle->numHistorySamples; i++) {
+            float weight = 1.0f / (float) (1+i);
+            //float weight = 1.0f;
+            result += weight * historyValue(handle, i);
+            totalWeight += weight;
+        }
+
+        result /= totalWeight;
+        return result;
+    }
+
+    // return false if playing done.
+    static bool advanceSound(SoundHandle *handle, float *out, unsigned int framesPerBuffer)
+    {
+        assert(handle != NULL);
+        assert(framesPerBuffer > 0);
+        assert(out != NULL);
+
+        if (handle == NULL || framesPerBuffer == 0 || out == NULL) {
+            return false;
+        }
+
+        // TODO: add length to sounds
+
+        // TODO: find out the period, write just one period and then copy the
+        // values.
+        //float dt = handle->freq / context.sampleRate;
+
+        // TODO: divide into three parts for envelops
+        // because they are linear in the phases so interpolating between that
+        // should be made easier
+
+        // advance parameters for testing
+        switch(handle->_type) {
+            //float div = 10.0;
+            //float t = (((int)(100*handle->time/div)) % 101) / 100.0;
+            //handle->leakage = 0.5+0.5*sin(2.0*M_PI*t);
+            default:
+                break;
+        }
+
+        const float dt = 1.0 / context.sampleRate;
+        const float ds = 2.0 * M_PI * handle->freq * dt;
+
+        // XXX too long range when becomes done
+        unsigned int i;
+        for (i=0; i<framesPerBuffer; i++) {
+            handle->time += dt;
+
+            // TODO: save this state too?
+            if (handle->time < 0.0) {
+                checkEnvelopeState(handle, Wait);
+                // this sound can not yet be heard
+                continue;
+            }
+
+            // TODO: add phase as argument.
+
+            float v;
+            switch (handle->_type) {
+            case SoundFrequency:
+                handle->state += ds;
+                v = sin(handle->state);
+                break;
+
+            case SoundWhiteNoise:
+                v = util::randf_m1_1();
+                break;
+
+            case SoundPinkNoise:
+                //v = (historyValue(handle, 0) + Randf_m1_1()) / 2.0f;
+                //saveHistoryValue(handle, v);
+                v = (handle->state + util::randf_m1_1()) / 2.0f;
+                handle->state = v;
+                break;
+
+            case SoundBrownianNoise:
+                // this is created by integrating white noise.
+
+                {
+                    float white = util::randf_m1_1();
+                    float p = handle->leakage * handle->state;
+                    float s = handle->scaling * white;
+                    float z = p + s;
+                    if (handle->skipDirectionIfClamping && fabsf(z) >= 1.0f) {
+                        z = p - s;
+                    }
+                    handle->state = z;
+                    v = z;
+                }
+                //v = sumHistory(handle, handle->freq, randf_m1_1());
+                //v = sumHistory(handle, 0.1, randf_m1_1());
+                //v = 0.2*historyValue(handle, 1) + 0.3*historyValue(handle, 0) + 0.5*randf_m1_1();
+                //v = (historyValue(handle, 1) + historyValue(handle, 0) + randf_m1_1()) / 3.0;
+                //saveHistoryValue(handle, v);
+
+#if 0
+                {
+                    float a = 0.8;
+                    v = a*handle->state + (1.0-a)*randf_m1_1();
+                    handle->state = v;
+                }
+#endif
+                break;
+
+            default:
+                printf("warning: unimplemented sound type for #%d: %d\n", handle->uid, handle->_type);
+                continue;
+            }
+
+            if (handle->_useEnvelope) {
+                v *= amplitudeForTime(handle);
+                if (handle->_done) {
+                    return false;
+                }
+            } else {
+                v *= handle->amplitude;
+            }
+
+            // add values from this sound te to current sound level
+            *out++ += v;
+            *out++ += v;
+        }
+
+        return true;
+    }
+
+    /* This routine will be called by the PortAudio engine when audio is needed.
+       It may called at interrupt level on some machines so don't do anything
+       that could mess up the system like calling malloc() or free().
+    */
+    static int sound_callback(const void *inputBuffer,
+                                    void *outputBuffer,
+                           unsigned long  framesPerBuffer,
+          const PaStreamCallbackTimeInfo *timeInfo,
+                   PaStreamCallbackFlags  statusFlags,
+                                    void *userData)
+    {
+        (void) inputBuffer;
+        (void) timeInfo;
+        (void) statusFlags;
+        (void) userData;
+
+        // update time
+        double now = timestamp_double();
+
+        // should not happen. just in case.
+        global_time = now - startup_time;
+
+        //printf("global time raw: %f\n", global_time);
+        if (global_time < 0.0) {
+            global_time = 0.0;
+        }
+
+        // we have 32 bit float format so cast here
+        float *out = (float *) outputBuffer;
+
+        // set all to zero
+        unsigned int i;
+        for (i=0; i<framesPerBuffer; i++) {
+            *out++ = 0.0f;
+            *out++ = 0.0f;
+        }
+
+        // reset pointer
+        out = (float *) outputBuffer;
+
+        // advance all sounds
+        for (i=0; i<context.highestSoundIndex; i++) {
+            SoundHandle *handle = context.sounds[i];
+            // XXX
+            if (handle == NULL) {
+                continue;
+            }
+
+            if (!handle->_done) {
+#if 0
+                    printf("play sound 0x%x with loop=%d, sample=%d, freq=%f amplitude=%f\n",
+                            (void*) handle,
+                            handle->looping,
+                            (unsigned int) handle->_currentSample, handle->freq, handle->amplitude);
+#endif
+
+                if (!advanceSound(handle, out, framesPerBuffer)) {
+                    handle->_done = true;
+                }
+            }
+
+            // TODO: when we should not free in the loop, where else?
+            if (handle->_done) {
+                //printf("[sound] %f freeing sound #%d handle 0x%p\n", global_time, handle->uid, handle);
+                context.sounds[i] = NULL;
+                if (!handle->keep_when_done) {
+                    deleteSound(handle);
+                }
+            }
+        }
+
+        // make sure all -1.0 >= x <= 1
+#if 0
+        out = outputBuffer;
+        for (i=0; i<2*framesPerBuffer; i++) {
+            if (*out < -1.0) { *out = -1.0; }
+            else if (*out > 1.0) { *out = 1.0; }
+        }
+#endif
+
+        if (context.dumping) {
+            dumpSamples((float *) outputBuffer, framesPerBuffer);
+        }
+
+        // TODO: check!
+#if 0
+        // apply post-processing
+        out = outputBuffer;
+        // advance all sounds
+        for (i=0; i<context.highestSoundIndex; i++) {
+            float v = *out;
+            v = pow(v, 2.0);
+            *out++ = v;
+
+            v = *out;
+            v = pow(v, 2.0);
+            *out++ = v;
+        }
+#endif
+
+        return 0;
+    }
+
+    bool initSound(void)
+    {
+        startup_time = timestamp_double();
+        global_time  = 0.0;
+
+        // TODO: make all customizable too
+        context.init = false; // for now, set on succes to true
+        context.dumping = false;
+        context.dump_filename = NULL;
+        context.sampleRate      = 44800;
+        context.framesPerBuffer = 256;
+        //context.framesPerBuffer = 1024;
+        //context.framesPerBuffer = 100;
+        //context.framesPerBuffer = 44100;
+
+        // TODO: add max number of simultanous playing sounds, that's more important.
+
+        context.sound_uid_counter = 0;
+        context.maxNumSounds      = 50;
+        context.highestSoundIndex = 0;
+        context.sounds = (SoundHandle **) calloc(context.maxNumSounds, 1000); // XXX HACK
+        assert(context.sounds != NULL);
+
+        PaError err = Pa_Initialize();
+        if (err != paNoError) {
+            printf("error: sound failed to initialize. error=%s\n", Pa_GetErrorText(err));
+            return false;
+
+        } else {
+            //printf("sound initialized :)");
+        }
+
+        int numDevices;
+        numDevices = Pa_GetDeviceCount();
+        if (numDevices < 0 ) {
+            printf("ERROR: Pa_CountDevices returned %i\n", numDevices);
+            return false;
+
+        } else {
+#if 0
+            printf("sound: num devices=%d\n", numDevices);
+            const PaDeviceInfo *deviceInfo;
+            int i;
+            for( i=0; i<numDevices; i++ ) {
+                deviceInfo = Pa_GetDeviceInfo( i );
+                printf("dev [%i]: %s\n", i, deviceInfo->name);
+            }
+#endif
+        }
+
+        /* Open an audio I/O stream. */
+        err = Pa_OpenDefaultStream(
+            &context.stream,
+            0,              /* no input channels */
+            2,              /* stereo output */
+            paFloat32,      /* 32 bit floating point output */
+            context.sampleRate,          /* sample rate */
+            context.framesPerBuffer,            /* frames per buffer */
+            sound_callback,            /* this is your callback function */
+            NULL);          /* callback function pointer */
+
+        if (err != paNoError) {
+            printf("error: opening default stream: %s\n", Pa_GetErrorText(err));
+            return false;
+        }
+
+        err = Pa_StartStream(context.stream);
+        if (err != paNoError) {
+            printf("error: starting default stream failed: %s\n", Pa_GetErrorText(err));
+            return false;
+        }
+
+        // clear that
+        //sound_context.num_active_handles = 0;
+        //sound_context.num_cached = 0;
+
+        context.init = true;
+        return true;
+    }
+
+    static void allocateHistory(SoundHandle *handle, size_t numHistorySamples)
+    {
+        handle->lastHistorySample = 0;
+
+        if (numHistorySamples == 0) {
+            handle->numHistorySamples = 0;
+            handle->history = NULL;
+            return;
+        }
+
+        handle->numHistorySamples = numHistorySamples;
+        handle->history = (float *) calloc(sizeof(float)*2, handle->numHistorySamples);
+
+        // clear all
+        size_t i;
+        for (i=0; i<2*handle->numHistorySamples; i++) {
+            handle->history[i] = 0.0f;
+        }
+    }
+
+    SoundHandle *playFrequency(float freq, float amplitude)
+    {
+        SoundHandle *handle = playSound(SoundFrequency, amplitude);
+        if (handle != NULL) {
+            handle->freq = freq;
+            //handle->looping = true;
+        }
+        return handle;
+    }
+
+    SoundHandle *playSound(enum Sound type, float amplitude)
+    {
+        if (!context.init) {
+            //printf("warning: called playSound() with no initialized sound system!\n");
+            return NULL;
+        }
+
+        size_t nextFreeIndex = 0;
+        while(nextFreeIndex < context.highestSoundIndex) {
+            if (context.sounds[nextFreeIndex] == NULL) {
+                // got an empyt sound to use
+                break;
+            }
+            nextFreeIndex++;
+        }
+
+        if (nextFreeIndex >= context.maxNumSounds) {
+            printf("error: can't create more sounds, got maximum of: %d\n", context.maxNumSounds);
+            return NULL;
+        }
+
+        SoundHandle *handle = (SoundHandle *) calloc(1, sizeof(SoundHandle));
+        handle->envelope = New;
+        handle->amplitude = amplitude;
+        handle->minAmplitude = 0.0;
+        handle->freq = 1000;
+        handle->looping = false;
+        handle->_loopCount = 0;
+        handle->_type = type;
+        handle->time = 0.0;
+        handle->keep_when_done = false;
+        handle->state = 0.0;
+        handle->leakage = 0.0;
+        handle->scaling = 0.0;
+        handle->_done = false;
+        handle->skipDirectionIfClamping = false;
+
+        handle->_useEnvelope = false;
+        handle->_riseTime    = 0.0;
+        handle->_relativeOvershootTime = 0.0;
+        handle->_decayTime   = 0.0;
+        handle->_holdTime    = 0.0;
+        handle->_waitTime    = 0.0;
+        handle->decayType    = SoundDecayLinear;
+        handle->riseType     = SoundDecayLinear;
+        handle->name         = "<unnamed>";
+
+        // filters may to access values from their history
+        int numHistoryValues = 0;
+
+        switch(type) {
+            // pink/white/brown noise need to save only one sample, state is enough
+            // for that.
+            case SoundBrownianNoise:
+                // something like lowpass filter constant.
+                // lower value == lower freq. noise
+                // values that audacity uses
+                //handle->leakage = 0.997;
+                //handle->scaling = 0.05;
+
+                handle->leakage = (context.sampleRate - 144.0) / context.sampleRate;
+                handle->scaling = 9.0 / sqrt(context.sampleRate);
+                //printf("computed leakage and scaling: %f %F\n", handle->leakage, handle->scaling);
+
+                //handle->leakage = 0.7;
+                //handle->scaling = 0.2;
+                handle->skipDirectionIfClamping = true;
+                break;
+
+            case SoundPinkNoise:
+                break;
+
+            case SoundWhiteNoise:
+                break;
+
+            default:
+                break;
+        }
+
+        allocateHistory(handle, numHistoryValues);
+
+        handle->uid = context.sound_uid_counter++;
+
+        context.sounds[nextFreeIndex] = handle;
+
+        if (nextFreeIndex == context.highestSoundIndex) {
+            context.highestSoundIndex++;
+        }
+
+        return handle;
+    }
+
+    bool stopSound(SoundHandle *handle)
+    {
+        if (!context.init) {
+            printf("warning: called stopSound() with no initialized sound system!\n");
+            return false;
+        }
+
+        if (handle == NULL) {
+            printf("warning: stopSound() handle is NULL\n");
+            return false;
+        }
+
+        if (handle->_done) {
+            printf("warning: stopSound() sound is already stopped\n");
+            return false;
+        }
+
+        // TODO: kill with variable
+        handle->_done = true;
+
+        return true;
+    }
+
+    void stopAllSounds(void)
+    {
+        if (!context.init) {
+            printf("warning: called stopAllSounds() with no initialized sound system!\n");
+        }
+
+        unsigned int i;
+        for (i=0; i<context.highestSoundIndex; i++) {
+            if (context.sounds[i] != NULL && !context.sounds[i]->_done) {
+                stopSound(context.sounds[i]);
+            }
+        }
+    }
+
+    void computeEnvelopeUse(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return;
+        }
+
+        // wait time has no influence (yet)
+        handle->_useEnvelope = (handle->_riseTime != 0.0 || handle->_holdTime != 0.0 || handle->_decayTime != 0.0);
+    }
+
+    bool configureEnvelope(SoundHandle *handle, float rise, float hold, float decay)
+    {
+        if (handle == NULL) {
+            return false;
+        }
+
+        // TODO: check inf/nan too
+        if (rise < 0.0) {
+            return false;
+        }
+        if (hold < 0.0) {
+            return false;
+        }
+        if (decay < 0.0) {
+            return false;
+        }
+
+        handle->_riseTime   = rise;
+        handle->_holdTime   = hold;
+        handle->_decayTime  = decay;
+
+        // set depending on flags
+        computeEnvelopeUse(handle);
+
+        return true;
+    }
+
+    bool configureEnvelopeLooping(SoundHandle *handle, float rise, float hold, float decay, float wait)
+    {
+        if (wait < 0.0) {
+            return false;
+        }
+
+        if (!configureEnvelope(handle, rise, hold, decay)) {
+            return false;
+        }
+
+        handle->looping = true;
+        handle->_loopCount = -1;
+        handle->_waitTime = wait;
+
+        return true;
+    }
+
+    float getRiseDuration(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return -1.0;
+        }
+
+        return handle->_riseTime;
+    }
+
+    float getHoldDuration(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return -1.0;
+        }
+
+        return handle->_holdTime;
+    }
+
+    float getDecayDuration(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return -1.0;
+        }
+
+        return handle->_decayTime;
+    }
+
+    float getwaitTime(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return -1.0;
+        }
+
+        return handle->_waitTime;
+    }
+
+    void teardownSound(void)
+    {
+        if (!context.init) {
+            printf("[sonud] can't teardown sound when not initialized!\n");
+            return;
+        }
+
+        PaError err = Pa_CloseStream(context.stream);
+        if (err != paNoError) {
+            printf("[sound] portaudio failed to close stream: %d\n", err);
+        }
+
+        err = Pa_Terminate();
+        if (err != paNoError) {
+            printf("[sound] portaudio failed to terminate: %d\n", err);
+        }
+
+        if (context.dumping) {
+            stopDumpingWav();
+        }
+
+        context.init = false;
+    }
+
+    bool configureOvershoot(SoundHandle *handle, float relativeOvershootTime)
+    {
+        if (handle == NULL) {
+            return false;
+        }
+        if (relativeOvershootTime < 0.0) {
+            return false;
+        }
+
+        handle->_relativeOvershootTime      = relativeOvershootTime;
+
+        return true;
+    }
+
+    void setLoopCount(SoundHandle *handle, int numRepetitions)
+    {
+        if (numRepetitions < -1) {
+            numRepetitions = -1;
+        }
+
+        handle->_loopCount = numRepetitions;
+
+        if (numRepetitions == 0) {
+            handle->looping = false;
+        } else if (numRepetitions == -1) {
+            handle->looping    = true;
+        } else {
+            handle->looping = true;
+        }
+    }
+
+    int numActiveSounds(void)
+    {
+        int num = 0;
+        size_t i;
+        for (i=0; i<context.highestSoundIndex; i++) {
+            if (context.sounds[i] != NULL) {
+                num++;
+            }
+        }
+        return num;
+    }
+
+    void deleteSound(SoundHandle *handle)
+    {
+        if (handle == NULL) {
+            return;
+        }
+
+        // just for sure
+        handle->_done = true;
+
+        // clear from that
+        size_t i;
+        for (i=0; i<context.highestSoundIndex; i++) {
+            if (context.sounds[i] == handle) {
+                context.sounds[i] = NULL;
+                if (i+1 == context.highestSoundIndex) {
+                    context.highestSoundIndex--;
+                }
+                break;
+            }
+        }
+
+        if (handle->history != NULL) {
+            free(handle->history);
+        }
+
+        free(handle);
+    }
+
+    bool configureEnvelopeWait(SoundHandle *handle, float rise, float hold, float decay, float wait)
+    {
+        if (configureEnvelopeLooping(handle, rise, hold, decay, wait)) {
+            handle->looping = false;
+            handle->_loopCount = -1;
+            return true;
+
+        } else {
+            return false;
+        }
+    }
+}

game/sound/sound.hpp

@@ -0,0 +1,185 @@
+#ifndef _SOUND_HPP_
+#define _SOUND_HPP_
+
+#include <stdlib.h>
+#include <stdbool.h>
+
+namespace sound {
+
+    // type of sound.
+    // the envelope settings modify each sound.
+    enum Sound {
+        SoundFrequency=0,   // one frequency
+        SoundWhiteNoise=1,  // all frequencies are equal
+        SoundBrownianNoise=2,  // 1/f^2 noise
+        SoundPinkNoise=3,   // 1/f noise
+    };
+
+    enum EnvelopeState {
+        New=0,   // newly spawned
+        Wait,  // ready but not yet started (waiting before starting or before repeating)
+        Rise,  // increasing
+        BeginOvershoot,
+        EndOvershoot,
+        Hold,  // staying at normal level
+        Decay, // deacying
+        Done,  // done
+    };
+
+    enum SoundDecayType {
+        SoundDecayLinear = 0,
+        SoundDecayExp    = 1
+    };
+
+    typedef struct {
+        // just for debugging/logging. don't rely on use
+        const char *name;
+
+        // unique ID for accessing them via lookups etc. if sound is dead, this will be never reused
+        int uid;
+
+        // if true, don't deallocate once this is done.
+        bool keep_when_done;
+
+        // these are public and can be changed by the user.
+        enum EnvelopeState envelope;
+
+        /****************************************************************/
+        /*             Special Parameters for specific types            */
+        /****************************************************************/
+
+        /******************** SoundFrequency ****************************/
+
+        float freq; // base frequency for type: SoundFrequency
+
+        /******************** White / Brownian / Pink Noise ****************/
+        float leakage; // influence of previous state on current value (0..1)
+        float scaling; // influence of white noise on next value
+
+        // If true and the value goes outside (-1..1), do the step in the other
+        // direction to stay inside the valid range.
+        bool skipDirectionIfClamping;
+
+        /******************** SoundFrequency: ***************************/
+
+        /****************************************************************/
+        /*             Common sound state / parameters                  */
+        /****************************************************************/
+        // progress of the sound which is used for the envelope but can be used for
+        // other things too
+        float time;
+
+        // scalar state that can be used arbitrarily to derive the waveform from it
+        float state;
+
+        // time when the sound is done
+        // if != 0.0, the sound changes with that
+        // TODO: make attack gain decay stuff as envelope
+        // TODO: add amplitude noise
+        float _riseTime;
+        float _relativeOvershootTime; // percentage of end of rise time that is used for overshoot (max amplitude at t_overshoot/2)
+        float _holdTime;
+        float _decayTime;
+        float _waitTime;
+
+        // waveform of type of rise. default: linear
+        enum SoundDecayType riseType;
+
+        // waveform of type of decay. default: linear
+        enum SoundDecayType decayType;
+
+        // if true, play infinitely
+        bool looping;
+
+        // base amplitude of the sound
+        float amplitude;
+
+        // amplitude when signal is at minimum (before rise, after release and in wait time)
+        float minAmplitude;
+
+        // these are al private!
+        // never acces them
+        enum Sound   _type; // which type of sound
+
+        int _loopCount;
+
+        // if true, will get removed
+        bool _done;
+        bool _useEnvelope;
+
+        float *history; // if != 0, history is a pointer to 2*numHistorySamples samples.
+        size_t numHistorySamples; // if != 0, save history for this sound.
+        size_t lastHistorySample; // index/2 of last history sample. used
+    } SoundHandle;
+
+    // initialize sound subsystem. return true if working, false on errors.
+    bool initSound(void);
+
+    // start playing a sound.
+    // args:
+    // type - type of sound.
+    // amplitude : 0..1
+    // handle: if != NULL will point to the internal sound handle to change the
+    // manipulate playing of the sound.
+    // TODO: add sound from file to play too
+    SoundHandle *playSound(enum Sound type, float amplitude);
+
+    // start playing a looping frequency.
+    // args:
+    // freq: frequency in Hz
+    SoundHandle *playFrequency(float freq, float amplitude);
+
+    // set them.
+    // args:
+    // time of phases
+    bool configureEnvelope(SoundHandle *handle, float rise, float hold, float decay);
+
+    bool configureOvershoot(SoundHandle *handle, float relativeOvershootTime);
+
+    // same as above but set to looping and set wait time between intervals
+    bool configureEnvelopeWait(SoundHandle *handle, float rise, float hold, float decay, float wait);
+
+    // without looping but with wait
+    bool configureEnvelopeLooping(SoundHandle *handle, float rise, float hold, float decay, float wait);
+
+    // getter for attributes. if 0.0, unused.
+    float getRiseDuration(SoundHandle *handle);
+    float getHoldDuration(SoundHandle *handle);
+    float getDecayDuration(SoundHandle *handle);
+
+    float getWaitTime(SoundHandle *handle);
+    void configureWaitTime(SoundHandle *handle, float waitTime);
+
+    // Set looping behaviour of the sound.
+    // args:
+    //                 / >   0, sound is looping for this number of repetitions
+    // numRepetitions {  ==  0, sound is stopped when it is over
+    //                 \ == -1, loop the sound forever
+    //
+    void setLoopCount(SoundHandle *handle, int numRepetitions);
+
+    // stop playing a sound. the handle is invalid now.
+    bool stopSound(SoundHandle *handle);
+
+    // stop and remove all playing sounds. all handle become invalid after calling
+    // this.
+    void stopAllSounds(void);
+
+    void teardownSound(void);
+
+    // for debugging
+    bool startDumpingWav(const char *filename);
+
+    // is deletede when 'keep' not set after stopping
+    void stopDumpingWav(void);
+
+    int numActiveSounds(void);
+
+    void deleteSound(SoundHandle *handle);
+
+    //SoundHandle *playFreqEnvelope(float freq, float rise, float hold, float decay);
+
+    // TODO: add fade out/fade in overlay stuff for stopping sounds smoothly
+}
+
+#endif

game/sound/sound_effects.cpp

@@ -0,0 +1,77 @@
+#include "sound_effects.hpp"
+
+#include "sound.hpp"
+
+namespace sound {
+#if 0
+    class MissileFlySoundEffect : public SoundEffect {
+        MissileFlySoundEffect(const game::Missile *missile)
+            : m_missileId(missile->id)
+            , m_handle(sound::playSound(sound::playFrequency(440, 0.3))
+        {
+        }
+
+        ~MissileFlySoundEffect()
+        {
+            delete(m_handle);
+        }
+
+        bool advance(float dt)
+        {
+            for (const game::StateUpdateEvent *event : updates) {
+                handleUpdateEvent(event);
+            }
+
+            // TODO: add event if sth. comes into life or dies in a state
+            // cycle.. delete objects that died last cycle in the current cycle
+            // so pointers don't get invalid.
+
+            bool keep = false;
+            for (const game::Missile *missile : state->missiles) {
+                if (missile->id == m_missileId) {
+                    keep = true;
+                    break;
+                }
+            }
+
+            if (!keep) {
+                sound::stopSound(m_handle);
+                sound::deleteSound(m_handle);
+                return false;
+            }
+
+            return true;
+        }
+
+        private:
+            SoundHandle *m_handle;
+            size_t       m_missileId;
+    };
+
+    void SoundEffects::advance(float dt, const std::list<game::StateUpdateEvent*> &updates)
+    {
+        //StateUpdateEvent::LifeCycle::Create,
+        //StateUpdateEvent::Type::Explosion
+
+        std::vector<SoundEffect*> rm;
+
+        for (SoundEffect *effect : m_effects) {
+            bool keep = effect->advance(dt, m_gameState);
+            if (!keep) {
+                rm.push_back(effect);
+            }
+        }
+
+        for (SoundEffect *effect : rm) {
+            m_effects.remove(rm);
+            delete(rm);
+        }
+
+        // spawn new sounds
+        //for (const game::Missile *missile : state->missiles) {
+        //    for (SoundEffect
+        //    if (missile->
+        //}
+    }
+#endif
+}

game/sound/sound_effects.hpp

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <list>
+
+#include "state/state.hpp"
+
+namespace sound {
+#if 0
+    namespace game {
+        class StateUpdateEvent;
+    }
+
+    class SoundEffect {
+    public:
+        virtual ~SoundEffects()
+        {
+        }
+
+        // return false if it can be deleted
+        virtual bool advance(float dt) = 0;
+    };
+
+    class SoundEffects {
+        public:
+            SoundEffects()
+            {
+            }
+
+            void handleUpdateEvent(game::StateUpdateEvent *event);
+            void advance(float dt, const std::list<game::StateUpdateEvent*> &updates);
+
+        private:
+            std::list<SoundEffect*> m_effects;
+    }
+#endif
+}

game/state/commands.cpp

@@ -14,18 +14,16 @@ namespace game {
 
         // angles are supplied in degrees and are CCW
         Missile *missile = new Missile(
+                state->generateMissileId(),
                 player,
                 player->ship->position,
                 -util::deg2rad(m_angle),
                 0.005*player->speed);
 
-        Trace *trace = new Trace(missile);
-        missile->trace = trace;
-
         player->energy -= player->speed;
         player->missiles.push_back(missile);
 
-        state->addTrace(trace);
+        state->addMissile(missile);
     }
 
     bool ShootCommand::ready(const Player *player, const State *state) const

game/state/events/explosion_event.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "state/explosion.hpp"
+#include "state/state_update_event.hpp"
+
+namespace game {
+    class ExplosionEvent : public StateUpdateEvent {
+    public:
+        ExplosionEvent(StateUpdateEvent::LifeCycle lifeCycle, Explosion *explosion)
+            : StateUpdateEvent(lifeCycle, StateUpdateEvent::EventType::Explosion)
+            , explosion(explosion)
+
+        {
+            std::string typeStr = StateUpdateEvent::lifeCycleToString(lifeCycle);
+            std::cout<<"created explosion event for id " << explosion->id << " of type " << typeStr << std::endl;
+        }
+
+    public:
+        Explosion *explosion;
+    };
+}

game/state/missile.cpp

@@ -11,8 +11,9 @@
 #include <glm/gtx/norm.hpp>
 
 namespace game {
-    Missile::Missile(Player *player, const glm::vec2 &pos, float angle, float speed)
+    Missile::Missile(size_t id, Player *player, const glm::vec2 &pos, float angle, float speed)
-        : player(player)
+        : id(id)
+        , player(player)
         , position(pos)
     {
         velocity = speed * glm::vec2(std::sin(angle), std::cos(angle));

game/state/missile.hpp

@@ -57,13 +57,14 @@ namespace game {
             int planetId;
         };
 
-        Missile(Player *player, const glm::vec2 &pos, float angle, float speed);
+        Missile(size_t id, Player *player, const glm::vec2 &pos, float angle, float speed);
         ~Missile();
 
         // try to advance. if something will be hit, return the first hit in
         // time.
         Missile::Event advance(const game::State *state, float dt);
 
+        const size_t id;
         Player      *player; // owner won't be hit by own missiles
         glm::vec2    position;
         glm::vec2    velocity;

game/state/player.hpp

@@ -14,7 +14,7 @@ namespace game {
 
     class Player {
     public:
-        int        id;
+        size_t     id;
         bool       alive;
         float      speed;
         float      energy;
@@ -23,7 +23,7 @@ namespace game {
         std::string name;
         std::list<Missile*> missiles;
 
-        Player(int id) : id(id), alive(true), speed(1.0), energy(0.0), ship(nullptr), name("<unnamed>")
+        Player(size_t id) : id(id), alive(true), speed(1.0), energy(0.0), ship(nullptr), name("<unnamed>")
         {
         }
 

game/state/state.cpp

@@ -15,6 +15,9 @@
 #include "trace.hpp"
 #include "explosion.hpp"
 
+#include "state_update_event.hpp"
+#include "events/explosion_event.hpp"
+
 #include "util.hpp"
 
 namespace game {
@@ -28,7 +31,8 @@ namespace game {
         //for (Player *player : players) {
         //}
 
-        m_nextId             = 0;
+        m_nextPlayerId             = 0;
+        m_nextMissileId      = 0;
         m_time               = 0.0;
         m_shipRadius         = 0.02;
         m_maxMissileDistance = 2.0;
@@ -146,15 +150,15 @@ namespace game {
         return true;
     }
 
-    int State::addPlayer()
+    size_t State::addPlayer()
     {
-        int playerId = m_nextId++;
+        size_t playerId = m_nextPlayerId++;
         Player *player = new Player(playerId);
         players.push_back(player);
         return playerId;
     }
 
-    void State::quitPlayer(int playerId)
+    void State::quitPlayer(size_t playerId)
     {
 		std::cout << playerId << " quit" << std::endl;
 
@@ -168,12 +172,12 @@ namespace game {
 		}
     }
 
-    void State::clear(int playerId)
+    void State::clear(size_t playerId)
     {
 		std::cout << playerId << " clear" << std::endl;
     }
 
-    void State::setName(int playerId, std::string name)
+    void State::setName(size_t playerId, std::string name)
     {
         // discard if not unique
         for (const Player *other : players) {
@@ -186,7 +190,7 @@ namespace game {
         playerForId(playerId)->name = name;
     }
 
-    void State::setSpeed(int playerId, double speed)
+    void State::setSpeed(size_t playerId, double speed)
     {
         playerForId(playerId)->speed = speed;
     }
@@ -338,12 +342,15 @@ namespace game {
 
 		for (Explosion *explosion : rm) {
 			explosions.remove(explosion);
-			delete(explosion);
+            m_nextEvents.push_back(new ExplosionEvent(StateUpdateEvent::LifeCycle::Destroy, explosion));
+			//delete(explosion);
 		}
     }
 
     void State::advance(float dt)
     {
+        //std::cout<<"[state] (init) cycle: update events length is " << m_nextEvents.size() << std::endl;
+
         m_time += dt;
 
         advancePlayerShipSpawns(dt);
@@ -355,9 +362,19 @@ namespace game {
         advancePlayerCommands(dt);
 
         advancePlayerMissiles(dt);
+
+        //std::cout<<"[state] (before move) cycle: update events length is " << m_nextEvents.size() << std::endl;
+
+        // put collected events into that list.
+        m_allEvents.push_back(std::move(m_nextEvents));
+
+        //std::cout<<"[state] (after move) cycle: update events length is " << m_nextEvents.size() << std::endl;
+
+        // finally remove things.
+        //m_nextEvents.clear();
     }
 
-    Player *State::playerForId(int playerId)
+    Player *State::playerForId(size_t playerId)
     {
         for (Player *p : players) {
             if (p->id == playerId) {
@@ -402,7 +419,7 @@ namespace game {
         }
     }
 
-    void State::commandForPlayer(int playerId, game::Command *cmd)
+    void State::commandForPlayer(size_t playerId, game::Command *cmd)
     {
         Player *player = playerForId(playerId);
         if (player != nullptr) {
@@ -425,6 +442,14 @@ namespace game {
         traces.push_back(trace);
     }
 
+    void State::addMissile(Missile *missile)
+    {
+        Trace *trace = new Trace(missile);
+        missile->trace = trace;
+
+        addTrace(trace);
+    }
+
     void State::deleteTrace(Trace *trace)
     {
         if (trace->missile != nullptr) {
@@ -442,7 +467,10 @@ namespace game {
             return;
         }
 
-        explosions.push_back(new Explosion(m_nextExplosionId++, evt->position, evt->missileVelocity, evt->hit));
+        Explosion *explosion = new Explosion(m_nextExplosionId++, evt->position, evt->missileVelocity, evt->hit);
+        explosions.push_back(explosion);
+
+        m_nextEvents.push_back(new ExplosionEvent(StateUpdateEvent::LifeCycle::Create, explosion));
     }
 
     void State::advanceTraceAges(float dt)
@@ -472,4 +500,23 @@ namespace game {
     {
         m_playingFieldSize = glm::vec2(width, height);
     }
+
+    size_t State::generateMissileId()
+    {
+        return m_nextMissileId++;
+    }
+
+    void State::applyAndClearAllOldStateUpdates()
+    {
+        // TODO: delete the items for events that are to be removed in proper
+        // way
+
+        for (std::list<StateUpdateEvent*> list : m_allEvents) {
+            for (StateUpdateEvent *evt : list) {
+                delete(evt);
+            }
+            list.clear();
+        }
+        m_allEvents.clear();
+    }
 }

game/state/state.hpp

@@ -28,6 +28,7 @@ namespace game {
     // forward declarations
     class Command;
     class Player;
+    class StateUpdateEvent;
 
     class Ship;
     class Trace;
@@ -53,15 +54,15 @@ namespace game {
 
         // The upper layer (network/renderer) calling these three functions
         // should keep id's unique and give one (network) input an id.
-        int addPlayer();
+        size_t addPlayer();
-        void clear(int playerId);
+        void clear(size_t playerId);
-        void setName(int playerId, std::string name);
+        void setName(size_t playerId, std::string name);
-        void setSpeed(int playerId, double speed);
+        void setSpeed(size_t playerId, double speed);
-        void quitPlayer(int playerId);
+        void quitPlayer(size_t playerId);
-        void commandForPlayer(int playerId, Command *cmd);
+        void commandForPlayer(size_t playerId, Command *cmd);
 
         // lookup. return nullptr on invalid playerId
-        Player *playerForId(int playerId);
+        Player *playerForId(size_t playerId);
 
         /*************************************************************************/
         /* Mixed stuff */
@@ -75,6 +76,9 @@ namespace game {
         // add a trace to the list of traces.
         void addTrace(Trace *trace);
 
+        // add a missile
+        void addMissile(Missile *missile);
+
         // delete traces with this command
         void deleteTrace(Trace *trace); // using a pointer
 
@@ -97,10 +101,17 @@ namespace game {
         void setPlayingFieldSize(int width, int height);
         void setPlayingFieldCenter(int width, int height);
 
+        size_t generateMissileId();
+
+        void applyAndClearAllOldStateUpdates();
+
+
         /*************************************************************************/
         /* Rendering */
         /*************************************************************************/
 
+        // TODO: hide and replace by events
+
         // Game items which should be rendered are here:
         // (access missiles by iterating over player's missiles attribute)
         std::vector<Planet*>  planets;
@@ -139,13 +150,17 @@ namespace game {
         float  m_playerRespawnTime;
         float  m_shipRadius;
         float  m_defaultEnergy;
-        int   m_nextId;
         int    m_maxNumTraces;
+        size_t m_nextPlayerId;
         size_t m_nextExplosionId;
+        size_t m_nextMissileId;
         float  m_time;
         bool   m_developerMode;
 
         glm::vec2 m_playingFieldCenter;
         glm::vec2 m_playingFieldSize;
+
+        std::list<StateUpdateEvent*>              m_nextEvents;
+        std::vector<std::list<StateUpdateEvent*>> m_allEvents;
     };
-};
+}

game/state/state_update_event.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <string>
+
+// TODO: make life cycle object class.
+// objects from that class can be created and destroyed only through factory
+// methods which create updates too.
+
+namespace game {
+    class StateUpdateEvent {
+    public:
+        enum class LifeCycle {
+            Create,  // something was created
+            Modify,  // something was modified (look at attributes)
+            Destroy  // something was destroyed
+        };
+
+        // add all possible classes here
+        enum class EventType {
+            Explosion
+        };
+
+        StateUpdateEvent(LifeCycle cycle, EventType event)
+            : m_lifeCycle(cycle), m_eventType(event)
+        {
+        }
+
+        LifeCycle lifeCycle() const { return m_lifeCycle; }
+        EventType eventType() const { return m_eventType; }
+
+        std::string description() const
+        {
+            // TODO
+            return "<event>";
+        }
+
+        static std::string lifeCycleToString(LifeCycle lifeCycle)
+        {
+            switch(lifeCycle) {
+                case StateUpdateEvent::LifeCycle::Create:  return "create";
+                case StateUpdateEvent::LifeCycle::Modify:  return "modify";
+                case StateUpdateEvent::LifeCycle::Destroy: return "destroy";
+                default: return "<invalid>";
+            }
+        }
+
+    private:
+        const LifeCycle m_lifeCycle;
+        const EventType m_eventType;
+    };
+}