Improve sound

main.c

@@ -94,7 +94,9 @@ static inline void SFG_setPixel(uint16_t x, uint16_t y, uint8_t colorIndex);
   samples provided in sounds.h, and it may or may not ignore the volume
   parameter (which is 0 to 255). Depending on the platform the function can play
   completely different samples or even e.g. just beeps. If the platform can't
-  play sounds, this function implementation can simply be left empty.
+  play sounds, this function implementation can simply be left empty. This
+  function doesn't have to implement safety measures, the back end takes cares
+  of them.
 */
 void SFG_playSound(uint8_t soundIndex, uint8_t volume);
 
@@ -248,6 +250,9 @@ struct
                                  for mouse control. */
 } SFG_player;
 
+uint8_t SFG_explosionSoundPlayed;  /**< Prevents playing too many explosion
+                                 sounds at once */
+
 RCL_RayConstraints SFG_rayConstraints;
 
 /**
@@ -350,6 +355,19 @@ uint8_t SFG_random()
   return SFG_currentRandom;
 }
 
+void SFG_playSoundSafe(uint8_t soundIndex, uint8_t volume)
+{
+  if (soundIndex == 2) // explosion?
+  {
+    if (!SFG_explosionSoundPlayed)
+      SFG_playSound(soundIndex,volume);
+    
+    SFG_explosionSoundPlayed = 1;
+  }
+  else
+    SFG_playSound(soundIndex,volume);
+}
+
 /**
   Returns a damage value for specific attack type (SFG_WEAPON_FIRE_TYPE_...),
   with added randomness (so the values will differe). For explosion pass
@@ -1772,6 +1790,8 @@ static inline uint8_t SFG_elementCollides(
 */
 void SFG_gameStep()
 {
+  SFG_explosionSoundPlayed = 0;
+
   for (uint8_t i = 0; i < SFG_KEY_COUNT; ++i)
     SFG_keyStates[i] = (SFG_keyStates[i] << 1) | SFG_keyPressed(i);
 
@@ -1812,7 +1832,7 @@ void SFG_gameStep()
 
     if (canShoot)
     {
-      SFG_playSound(0,255);
+      SFG_playSoundSafe(0,255);
 
       if (ammo != SFG_AMMO_NONE)
         SFG_player.ammo[ammo] -= projectileCount;
@@ -2184,7 +2204,7 @@ void SFG_gameStep()
           SFG_removeItem(i);
           SFG_player.lastItemTakenFrame = SFG_gameFrame;
           i--;
-          SFG_playSound(3,255);
+          SFG_playSoundSafe(3,255);
 #endif
         }
         else // collide
@@ -2407,7 +2427,7 @@ void SFG_gameStep()
                  SFG_DOOR_UP_DOWN_MASK : 0x00; 
 
       if (upDownState != newUpDownState)
-        SFG_playSound(1,255);
+        SFG_playSoundSafe(1,255);
 
       door->state = (door->state & ~SFG_DOOR_UP_DOWN_MASK) | newUpDownState;
 
@@ -2533,7 +2553,7 @@ void SFG_gameStep()
       else if (monster->health == 0)
       {
         monster->stateType = SFG_MR_TYPE(*monster) | SFG_MONSTER_STATE_DYING;
-        SFG_playSound(2,255);
+        SFG_playSoundSafe(2,255);
       }
       else if (state != SFG_MONSTER_STATE_INACTIVE)
       {

platform_sdl.h

@@ -173,33 +173,37 @@ void emscripten_set_main_loop(em_callback_func func, int fps, int simulate_infin
 #endif
 
 uint8_t audioBuff[SFG_SFX_SAMPLE_COUNT];
-uint32_t audioPos = 0;
+uint16_t audioPos = 0;
 
 void audioFillCallback(void *userdata, uint8_t *s, int l)
 {
-  if (audioPos >= SFG_SFX_SAMPLE_COUNT)
-    SDL_PauseAudio(1);
-
   for (int i = 0; i < l; ++i)
-    if (audioPos < SFG_SFX_SAMPLE_COUNT)
-    {
-      s[i] = audioBuff[audioPos];
-      audioPos++;
-    }
-    else
-      s[i] = 127;
+  {
+    s[i] = audioBuff[audioPos];
+
+    audioBuff[audioPos] = 127;
+
+    audioPos = (audioPos < SFG_SFX_SAMPLE_COUNT - 1) ? (audioPos + 1) : 0;
+  }
 }
 
 void SFG_playSound(uint8_t soundIndex, uint8_t volume)
 {
   uint8_t volumeStep = volume / 16;
 
+  uint16_t pos = audioPos;
+
   for (int i = 0; i < SFG_SFX_SAMPLE_COUNT; ++i)
-    audioBuff[i] = SFG_GET_SFX_SAMPLE(soundIndex,i) * volumeStep;
+  {
+    int16_t mixedValue =
+      audioBuff[pos] - 127 + SFG_GET_SFX_SAMPLE(soundIndex,i) * volumeStep;
 
-  audioPos = 0;
- 
-  SDL_PauseAudio(0);
+    mixedValue = (mixedValue > 0) ? ((mixedValue < 255) ? mixedValue : 255) : 0;
+
+    audioBuff[pos] = mixedValue; 
+
+    pos = (pos < SFG_SFX_SAMPLE_COUNT - 1) ? (pos + 1) : 0;
+  }
 }
 
 int main(int argc, char *argv[])
@@ -278,6 +282,11 @@ int main(int argc, char *argv[])
   if (SDL_OpenAudio(&audioSpec, NULL) < 0)
     printf("SDL: could not initialize audio\n");
 
+  for (int i = 0; i < SFG_SFX_SAMPLE_COUNT; ++i)
+    audioBuff[i] = 127;
+
+  SDL_PauseAudio(0);
+
   running = 1;
 
 #ifdef __EMSCRIPTEN__
@@ -289,6 +298,7 @@ int main(int argc, char *argv[])
 
   printf("SDL: freeing SDL\n");
 
+  SDL_PauseAudio(1);
   SDL_DestroyTexture(texture);
   SDL_DestroyRenderer(renderer); 
   SDL_DestroyWindow(window);