add stereo panning

2 files changed, 60 insertions, 5 deletions

diff --git a/src/channel.c b/src/channel.c
index a29e7f7..d039701 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -106,8 +106,15 @@ void channel_get_next_sample(float *left, float *right, struct channel_t *chan)
 		float l, r;
 		l = chan->sound.left[chan->pos];
 		r = chan->sound.right[chan->pos];
-		*left = volume * l;
-		*right = volume * r;
+
+		float pan_l = ((float)p_atomic_int_get(&(chan->pan_left)))/128;
+		float pan_r = ((float)p_atomic_int_get(&(chan->pan_right)))/128;
+		float gain_ll, gain_lr, gain_rl, gain_rr;
+		pan_gain(&gain_ll, &gain_lr, pan_l);
+		pan_gain(&gain_rl, &gain_rr, pan_r);
+
+		*left = volume * ((gain_ll * l) + (gain_rl * r));
+		*right = volume * ((gain_lr * l) + (gain_rr * r));
 	}
 
 	chan->pos += 1;
diff --git a/src/channel.test.c b/src/channel.test.c
index 150adb9..789756d 100644
--- a/src/channel.test.c
+++ b/src/channel.test.c
@@ -385,15 +385,13 @@ void test_channel_get_next_sample_mono_panned()
 	
 	float l, r;
 
-	const float gain = 0.7071; /* constant-power panning center gain */
-
 	lily_store_value(mock_p_mutex_trylock, pboolean, TRUE);
 	channel_get_next_sample(&l, &r, &chan);
 	lily_assert_int_equal(mock_p_mutex_trylock->n_calls, 1);
 	lily_assert_int_equal(mock_p_mutex_unlock->n_calls, 1);
 	lily_assert_int_equal(chan.pos, 1);
 	lily_assert_float_equal(l, 0.0f, 0.1f);
-	lily_assert_float_equal(r, gain * 0.0f, 0.1f);
+	lily_assert_float_equal(r, 0.0f, 0.1f);
 
 	lily_store_value(mock_p_mutex_trylock, pboolean, TRUE);
 	channel_get_next_sample(&l, &r, &chan);
@@ -414,6 +412,55 @@ void test_channel_get_next_sample_mono_panned()
 }
 
 
+void test_channel_get_next_sample_panned()
+{
+	lily_mock_use(&mock_p_mutex_trylock);
+	lily_mock_use(&mock_p_mutex_unlock);
+
+	struct channel_t chan;
+	chan.active = true;
+	chan.paused = false;
+	chan.volume = 255;
+	chan.pan_left = 128;
+	chan.pan_right = 0;
+	float audio_left[] = { 0.2, 0.5, 1.0 };
+	float audio_right[] = { 1.0, 0.5, 0.2 };
+	chan.sound.left = audio_left;
+	chan.sound.right = audio_right;
+	chan.sound.mono = false;
+	chan.sound.len = 3;
+	chan.pos = 0;
+	
+	float l, r;
+	const float gain = 0.7071; /* constant-power panning center gain */
+
+	lily_store_value(mock_p_mutex_trylock, pboolean, TRUE);
+	channel_get_next_sample(&l, &r, &chan);
+	lily_assert_int_equal(mock_p_mutex_trylock->n_calls, 1);
+	lily_assert_int_equal(mock_p_mutex_unlock->n_calls, 1);
+	lily_assert_int_equal(chan.pos, 1);
+	lily_assert_float_equal(l, gain * 1.0f, 0.1f);
+	lily_assert_float_equal(r, gain * 1.0f + 0.2f, 0.1f);
+
+	lily_store_value(mock_p_mutex_trylock, pboolean, TRUE);
+	channel_get_next_sample(&l, &r, &chan);
+	lily_assert_int_equal(mock_p_mutex_trylock->n_calls, 2);
+	lily_assert_int_equal(mock_p_mutex_unlock->n_calls, 2);
+	lily_assert_int_equal(chan.pos, 2);
+	lily_assert_float_equal(l, gain * 0.5f, 0.1f);
+	lily_assert_float_equal(r, gain * 0.5f + 0.5f, 0.1f);
+
+	lily_store_value(mock_p_mutex_trylock, pboolean, TRUE);
+	channel_get_next_sample(&l, &r, &chan);
+	lily_assert_int_equal(mock_p_mutex_trylock->n_calls, 3);
+	lily_assert_int_equal(mock_p_mutex_unlock->n_calls, 3);
+	lily_assert_int_equal(chan.pos, 0);
+	lily_assert_int_equal(chan.active, false);
+	lily_assert_float_equal(l, gain * 0.2f, 0.1f);
+	lily_assert_float_equal(r, gain * 0.2f + 1.0f, 0.1f);
+}
+
+
 
 void suite_channel()
 {
@@ -431,6 +478,7 @@ void suite_channel()
 	lily_run_test(test_channel_get_next_sample_volume_0);
 	lily_run_test(test_channel_get_next_sample_mono);
 	lily_run_test(test_channel_get_next_sample_mono_panned);
+	lily_run_test(test_channel_get_next_sample_panned);
 
 	lily_mock_destroy(mock_p_mutex_new);
 }