medfall

commit 8f6374e67f3c1587b45bbc5bbf39d8e7099983ec
parent d86d284a8c3f56b1e6ddb9b62228ea98591cae9c
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sun Nov  1 19:30:09 +0000

Add audio mixer

Diffstat:
audio.cc
 | 
61
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
audio.h
 | 
36
++++++++++++++++++++++++++++++++++++
2 files changed, 97 insertions(+), 0 deletions(-)
diff --git a/audio.cc b/audio.cc
@@ -0,0 +1,61 @@
+#include "intrinsics.h"
+#include "audio.h"
+#include "assets.h"
+#include "memory_arena.h"
+#include "platform_barrier.h"
+#include "platform_atomic.h"
+
+static PlayingSound playing_sounds_head;
+
+PlayingSound * audio_play_sound( MemoryArena * arena, Sound sound, bool loop ) {
+	PlayingSound * ps = memarena_push_type( arena, PlayingSound );
+	*ps = { };
+
+	ps->sound = sound;
+	ps->volume[ 0 ] = ps->volume[ 1 ] = 1.0f;
+	ps->loop = loop;
+
+	write_barrier();
+
+	ps->next = playing_sounds_head.next;
+	playing_sounds_head.next = ps;
+
+	return ps;
+}
+
+void audio_fill_output_buffer( AudioOutputBuffer * buffer ) {
+	for( u32 i = 0; i < buffer->num_samples; i++ ) {
+		buffer->samples[ i ] = 0;
+	}
+
+	PlayingSound * prev = &playing_sounds_head;
+	PlayingSound * ps = prev->next;
+
+	while( ps ) {
+		assert( ps->sound.sample_rate == buffer->sample_rate );
+
+		u32 samples_to_write = buffer->num_samples;
+		if( !ps->loop ) {
+			samples_to_write = min_u32( ps->sound.num_samples - ps->num_played_samples, samples_to_write );
+		}
+
+		for( u32 i = 0; i < samples_to_write; i++ ) {
+			// we should do this in float buffers or we get horrible clipping when things overflow
+			buffer->samples[ i ] += ps->sound.samples[ ( i + ps->num_played_samples ) % ps->sound.num_samples ];
+		}
+
+		ps->num_played_samples += samples_to_write;
+		if( ps->num_played_samples >= ps->sound.num_samples ) {
+			if( ps->loop ) {
+				ps->num_played_samples %= ps->sound.num_samples;
+			}
+			else {
+				// atm we just leak ps
+				prev->next = ps->next;
+			}
+		}
+
+		prev = ps;
+		ps = ps->next;
+	}
+}
diff --git a/audio.h b/audio.h
@@ -0,0 +1,36 @@
+#ifndef _AUDIO_H_
+#define _AUDIO_H_
+
+#include "intrinsics.h"
+#include "assets.h"
+#include "memory_arena.h"
+
+struct PlayingSound {
+	Sound sound;
+
+	float volume[ 2 ];
+	bool loop;
+
+	u32 num_played_samples;
+
+	bool positional;
+	glm::vec3 position;
+
+	PlayingSound * next;
+};
+
+struct AudioOutputBuffer {
+	u32 sample_rate;
+	u32 num_samples;
+
+	s16 * samples;
+};
+
+struct PlaySoundOptions {
+	bool loop;
+};
+
+PlayingSound * audio_play_sound( MemoryArena * arena, Sound sound, bool loop = false );
+void audio_fill_output_buffer( AudioOutputBuffer * buffer );
+
+#endif // _AUDIO_H_