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Added fading in/out of music and samples.

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Stephane Peter committed Oct 23, 1999
1 parent 709e851 commit ef53e19d56f4f1b64b403a298725270e1d671300
Showing with 252 additions and 33 deletions.
  1. +110 −5 mixer.c
  2. +22 −0 mixer.h
  3. +115 −27 music.c
  4. +5 −1 playmus.c
115 mixer.c
@@ -42,6 +42,10 @@ static struct _Mix_Channel {
Uint8 *samples;
int volume;
int looping;
Mix_Fading fading;
int fade_volume;
int fade_length;
Uint32 ticks_fade;
} channel[MIX_CHANNELS];

#define MUSIC_VOL 64 /* Music volume 0-64 */
@@ -63,6 +67,23 @@ static void mix_channels(void *udata, Uint8 *stream, int len)
SDL_mutexP(mixer_lock);
num_channels = 0;
for ( i=0; i<MIX_CHANNELS; ++i ) {
if ( channel[i].fading != MIX_NO_FADING ) {
Uint32 ticks = SDL_GetTicks() - channel[i].ticks_fade;
if( ticks > channel[i].fade_length ) {
if( channel[i].fading == MIX_FADING_OUT ) {
channel[i].playing = 0;
Mix_Volume(i, channel[i].fading); /* Restore the volume */
}
channel[i].fading = MIX_NO_FADING;
} else {
if( channel[i].fading == MIX_FADING_OUT ) {
Mix_Volume(i, (channel[i].fade_volume * (channel[i].fade_length-ticks))
/ channel[i].fade_length );
} else {
Mix_Volume(i, (channel[i].fade_volume * ticks) / channel[i].fade_length );
}
}
}
if ( channel[i].playing && !channel[i].paused ) {
++ num_channels;
mixable = channel[i].playing;
@@ -368,6 +389,53 @@ int Mix_PlayChannel(int which, Mix_Chunk *chunk, int loops)
channel[which].looping = loops;
channel[which].chunk = chunk;
channel[which].paused = 0;
channel[which].fading = MIX_NO_FADING;
}
}
SDL_mutexV(mixer_lock);

/* Return the channel on which the sound is being played */
return(which);
}

/* Fade in a sound on a channel, over ms milliseconds */
int Mix_FadeInChannel(int which, Mix_Chunk *chunk, int loops, int ms)
{
int i;

/* Don't play null pointers :-) */
if ( chunk == NULL ) {
return(-1);
}

/* Lock the mixer while modifying the playing channels */
SDL_mutexP(mixer_lock);
{
/* If which is -1, play on the first free channel */
if ( which == -1 ) {
for ( i=reserved_channels; i<MIX_CHANNELS; ++i ) {
if ( channel[i].playing <= 0 )
break;
}
if ( i == MIX_CHANNELS ) {
which = -1;
} else {
which = i;
}
}

/* Queue up the audio data for this channel */
if ( which >= 0 ) {
channel[which].samples = chunk->abuf;
channel[which].playing = chunk->alen;
channel[which].looping = loops;
channel[which].chunk = chunk;
channel[which].paused = 0;
channel[which].fading = MIX_FADING_IN;
channel[which].fade_volume = channel[which].volume;
channel[which].volume = 0;
channel[which].fade_length = ms;
channel[which].ticks_fade = SDL_GetTicks();
}
}
SDL_mutexV(mixer_lock);
@@ -390,12 +458,13 @@ int Mix_Volume(int which, int volume)
prev_volume /= MIX_CHANNELS;
} else {
prev_volume = channel[which].volume;
if ( volume >= 0 ) {
if ( volume > SDL_MIX_MAXVOLUME ) {
volume = SDL_MIX_MAXVOLUME;
}
channel[which].volume = volume;
if ( volume < 0 ) {
volume = 0;
}
if ( volume > SDL_MIX_MAXVOLUME ) {
volume = SDL_MIX_MAXVOLUME;
}
channel[which].volume = volume;
}
return(prev_volume);
}
@@ -426,11 +495,47 @@ int Mix_HaltChannel(int which)
} else {
SDL_mutexP(mixer_lock);
channel[which].playing = 0;
if(channel[which].fading != MIX_NO_FADING) /* Restore volume */
channel[which].volume = channel[which].fade_volume;
channel[which].fading = MIX_NO_FADING;
SDL_mutexV(mixer_lock);
}
return(0);
}

/* Fade out a channel and then stop it automatically */
int Mix_FadeOutChannel(int which, int ms)
{
int status;

status = 0;
if ( which == -1 ) {
int i;

for ( i=0; i<MIX_CHANNELS; ++i ) {
status += Mix_FadeOutChannel(i,ms);
}
} else {
SDL_mutexP(mixer_lock);
if ( channel[which].playing && channel[which].volume>0 &&
channel[which].fading==MIX_NO_FADING ) {

channel[which].fading = MIX_FADING_OUT;
channel[which].fade_volume = channel[which].volume;
channel[which].fade_length = ms;
channel[which].ticks_fade = SDL_GetTicks();
++ status;
}
SDL_mutexV(mixer_lock);
}
return(status);
}

Mix_Fading Mix_FadingChannel(int which)
{
return channel[which].fading;
}

/* Check the status of a specific channel.
If the specified channel is -1, check all channels.
*/
22 mixer.h
@@ -50,6 +50,13 @@ typedef struct {
Uint8 volume; /* Per-sample volume, 0-128 */
} Mix_Chunk;

/* The different fading types supported */
typedef enum {
MIX_NO_FADING,
MIX_FADING_OUT,
MIX_FADING_IN
} Mix_Fading;

/* The internal format for a music chunk interpreted via mikmod */
typedef struct _Mix_Music Mix_Music;

@@ -98,6 +105,10 @@ extern int Mix_ReserveChannels(int num);
extern int Mix_PlayChannel(int channel, Mix_Chunk *chunk, int loops);
extern int Mix_PlayMusic(Mix_Music *music, int loops);

/* Fade in music or a channel over "ms" milliseconds, same semantics as the "Play" functions */
extern int Mix_FadeInMusic(Mix_Music *music, int loops, int ms);
extern int Mix_FadeInChannel(int channel, Mix_Chunk *chunk, int loops, int ms);

/* Set the volume in the range of 0-128 of a specific channel or chunk.
If the specified channel is -1, set volume for all channels.
Returns the original volume.
@@ -111,6 +122,17 @@ extern int Mix_VolumeMusic(int volume);
extern int Mix_HaltChannel(int channel);
extern int Mix_HaltMusic(void);

/* Halt a channel, fading it out progressively till it's silent
The ms parameter indicates the number of milliseconds the fading
will take.
*/
extern int Mix_FadeOutChannel(int which, int ms);
extern int Mix_FadeOutMusic(int ms);

/* Query the fading status of a channel */
extern Mix_Fading Mix_FadingMusic(void);
extern Mix_Fading Mix_FadingChannel(int which);

/* Pause/Resume a particular channel */
extern void Mix_Pause(int channel);
extern void Mix_Resume(int channel);

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