sound, music, mixer

platform/sdl/sound_mixer.h

@@ -0,0 +1,104 @@
+#pragma once
+#include "wave_mixer.h"
+
+#include <algorithm>
+#include <optional>
+#include <vector>
+
+template<int channels>
+class SoundMixer {
+public:
+
+
+    void mix_to_buffer(float *buffer, std::size_t samples_len) {
+        std::lock_guard _(_mx);
+        for (std::size_t i = 0; i < _tracks.size(); ++i) {
+            Track &t = _tracks[i];
+            bool playing = t.wave.output_mix(buffer, samples_len);
+            if (!playing) {
+                Track &b = _tracks.back();
+                if (&b != &t) std::swap(b,t);
+                _tracks.pop_back();
+                --i;
+            }
+        }
+    }
+
+    template<std::invocable<WaveMixer<channels> &> Fn>
+    bool visit_track(int trackID, Fn &&fn) {
+        std::lock_guard _(_mx);
+        Track *t = find_track_by_id(trackID);
+        if (t) {
+            fn(t->wave);
+            return true;
+        } else {
+            return false;
+        }
+
+    }
+    template<std::invocable<const WaveMixer<channels> &> Fn>
+    bool visit_track(int trackID, Fn &&fn) const {
+        std::lock_guard _(_mx);
+        const Track *t = find_track_by_id(trackID);
+        if (t) {
+            fn(t->wave);
+            return true;
+        } else {
+            return false;
+        }
+
+    }
+
+    void set_track(int trackID, WaveMixer<channels> wave) {
+        std::lock_guard _(_mx);
+        Track *t = find_track_by_id(trackID);
+        if (t) t->wave = std::move(wave);
+        else _tracks.push_back({trackID, std::move(wave)});
+    }
+
+    struct Track {
+        int trackID;
+        WaveMixer<channels> wave;
+    };
+
+
+    void set_tracks(Track *tracks, int count) {
+        std::lock_guard _(_mx);
+        for (int i = 0; i < count; ++i) {
+            Track *t = find_track_by_id(tracks[i].trackID);
+            if (t) t->wave = std::move(tracks[i].wave);
+            else _tracks.push_back(std::move(tracks[i]));
+        }
+    }
+
+
+protected:
+
+    Track *find_track_by_id(int track) {
+        auto iter = std::find_if(_tracks.begin(), _tracks.end(), [&](const Track &t){
+            return t.trackID == track;
+        });
+        if (iter == _tracks.end()) {
+            return nullptr;
+        } else {
+            return &(*iter);
+        }
+    }
+
+    const Track *find_track_by_id(int track) const {
+        auto iter = std::find_if(_tracks.begin(), _tracks.end(), [&](const Track &t){
+            return t.trackID == track;
+        });
+        if (iter == _tracks.end()) {
+            return nullptr;
+        } else {
+            return &(*iter);
+        }
+    }
+
+
+    std::mutex _mx;
+    std::vector<Track> _tracks;
+
+
+};