sfx: add volume control to sfx_play()

Preparatory commit for experimenting with varying volumes based
on distance.  Impetus is an interest in making the TV clips
always play when the TV appears, but vary the volume with
distance.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/sfx.c b/src/sfx.c
index 04b0fbc..334833a 100644
--- a/src/sfx.c
+++ b/src/sfx.c
@@ -63,10 +63,16 @@ void sfx_init(void)
 }
 
 
-void sfx_play(sfx_sound_t *sound)
+/* play sfx, volume 0-1 */
+void sfx_play(sfx_sound_t *sound, float volume)
 {
 	assert(sound);
 
+	if (volume > 1.f)
+		volume = 1.f;
+	else if (volume < 0.f)
+		volume = 0.f;
+
 	if (sound->chunk) {
 		int	channel;
 
@@ -74,6 +80,7 @@ void sfx_play(sfx_sound_t *sound)
 		if (channel < 0)
 			channel = Mix_GroupOldest(sound->voice);
 
+		Mix_Volume(channel, MIX_MAX_VOLUME * volume);
 		Mix_PlayChannel(channel, sound->chunk, 0);
 	}
 }