Add support for fading in to sound groups.

research/ma_engine.c

@@ -37,6 +37,7 @@ int main(int argc, char** argv)
 
     //ma_engine_sound_group_set_pan(&engine, NULL, -1);
     ma_engine_sound_group_set_pitch(&engine, NULL, 1.0f);
+    ma_engine_sound_group_set_fade_in(&engine, NULL, 4000);
     
     /*ma_engine_sound_set_volume(&engine, &sound, 0.25f);*/
     //ma_engine_sound_set_pitch(&engine, &sound, 2.0f);
@@ -58,7 +59,7 @@ int main(int argc, char** argv)
     ma_engine_play_sound(&engine, argv[3], NULL);*/
 #endif
 
-#if 1
+#if 0
     float pitch     = 1;
     float pitchStep = 0.01f;
     float pitchMin  = 0.125f;

research/ma_engine.h

@@ -997,6 +997,7 @@ MA_API ma_result ma_engine_sound_group_set_gain_db(ma_engine* pEngine, ma_sound_
 MA_API ma_result ma_engine_sound_group_set_effect(ma_engine* pEngine, ma_sound_group* pGroup, ma_effect* pEffect);
 MA_API ma_result ma_engine_sound_group_set_pan(ma_engine* pEngine, ma_sound_group* pGroup, float pan);
 MA_API ma_result ma_engine_sound_group_set_pitch(ma_engine* pEngine, ma_sound_group* pGroup, float pitch);
+MA_API ma_result ma_engine_sound_group_set_fade_in(ma_engine* pEngine, ma_sound_group* pGroup, ma_uint64 fadeTimeInMilliseconds);
 
 MA_API ma_result ma_engine_listener_set_position(ma_engine* pEngine, ma_vec3 position);
 MA_API ma_result ma_engine_listener_set_rotation(ma_engine* pEngine, ma_quat rotation);
@@ -6554,6 +6555,19 @@ MA_API ma_result ma_engine_sound_group_set_pitch(ma_engine* pEngine, ma_sound_gr
     return MA_SUCCESS;
 }
 
+MA_API ma_result ma_engine_sound_group_set_fade_in(ma_engine* pEngine, ma_sound_group* pGroup, ma_uint64 fadeTimeInMilliseconds)
+{
+    if (pEngine == NULL) {
+        return MA_INVALID_ARGS;
+    }
+
+    if (pGroup == NULL) {
+        pGroup = &pEngine->masterSoundGroup;
+    }
+
+    return ma_dual_fader_set_fade(&pGroup->effect.fader, 0, 0, 1, pGroup->effect.fader.timeInFramesCur, pGroup->effect.fader.timeInFramesCur + (fadeTimeInMilliseconds * pGroup->effect.fader.config.sampleRate) / 1000);
+}
+
 
 MA_API ma_result ma_engine_listener_set_position(ma_engine* pEngine, ma_vec3 position)
 {