Document the different filter types, and combine some split lines

2 files changed, 20 insertions, 36 deletions

diff --git a/OpenAL32/Include/alFilter.h b/OpenAL32/Include/alFilter.h
index 4a66ef9b..86547182 100644
--- a/OpenAL32/Include/alFilter.h
+++ b/OpenAL32/Include/alFilter.h
@@ -15,12 +15,18 @@ extern "C" {
  * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt                   */
 
 typedef enum ALfilterType {
+    /** EFX-style low-pass filter, specifying a gain and reference frequency. */
     ALfilterType_HighShelf,
+    /** EFX-style high-pass filter, specifying a gain and reference frequency. */
     ALfilterType_LowShelf,
+    /** Peaking filter, specifying a gain, reference frequency, and bandwidth. */
     ALfilterType_Peaking,
 
+    /** Low-pass cut-off filter, specifying a cut-off frequency and bandwidth. */
     ALfilterType_LowPass,
+    /** High-pass cut-off filter, specifying a cut-off frequency and bandwidth. */
     ALfilterType_HighPass,
+    /** Band-pass filter, specifying a center frequency and bandwidth. */
     ALfilterType_BandPass,
 } ALfilterType;
 
diff --git a/OpenAL32/alFilter.c b/OpenAL32/alFilter.c
index 70595aa0..ade41f4c 100644
--- a/OpenAL32/alFilter.c
+++ b/OpenAL32/alFilter.c
@@ -349,44 +349,22 @@ void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat g
     switch(type)
     {
         case ALfilterType_HighShelf:
-            alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f/gain) *
-                                            (1.0f/0.75f - 1.0f) + 2.0f);
-            filter->b[0] = gain * ((gain + 1.0f) +
-                                   (gain - 1.0f) * cosf(w0) +
-                                   2.0f * sqrtf(gain) * alpha);
-            filter->b[1] = -2.0f * gain * ((gain - 1.0f) +
-                                           (gain + 1.0f) * cosf(w0));
-            filter->b[2] = gain * ((gain + 1.0f) +
-                                   (gain - 1.0f) * cosf(w0) -
-                                   2.0f * sqrtf(gain) * alpha);
-            filter->a[0] = (gain + 1.0f) -
-                           (gain - 1.0f) * cosf(w0) +
-                           2.0f * sqrtf(gain) * alpha;
-            filter->a[1] = 2.0f * ((gain - 1.0f) -
-                           (gain + 1.0f) * cosf(w0));
-            filter->a[2] = (gain + 1.0f) -
-                           (gain - 1.0f) * cosf(w0) -
-                           2.0f * sqrtf(gain) * alpha;
+            alpha = sinf(w0)/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
+            filter->b[0] =       gain*((gain+1.0f) + (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha);
+            filter->b[1] = -2.0f*gain*((gain-1.0f) + (gain+1.0f)*cosf(w0)                         );
+            filter->b[2] =       gain*((gain+1.0f) + (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha);
+            filter->a[0] =             (gain+1.0f) - (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha;
+            filter->a[1] =  2.0f*     ((gain-1.0f) - (gain+1.0f)*cosf(w0)                         );
+            filter->a[2] =             (gain+1.0f) - (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha;
             break;
         case ALfilterType_LowShelf:
-            alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f / gain) *
-                                            (1.0f / 0.75f - 1.0f) + 2.0f);
-            filter->b[0] = gain * ((gain + 1.0f) -
-                                   (gain - 1.0f) * cosf(w0) +
-                                   2.0f * sqrtf(gain) * alpha);
-            filter->b[1] = 2.0f * gain * ((gain - 1.0f) -
-                                          (gain + 1.0f) * cosf(w0));
-            filter->b[2] = gain * ((gain + 1.0f) -
-                                   (gain - 1.0f) * cosf(w0) -
-                                   2.0f * sqrtf(gain) * alpha);
-            filter->a[0] = (gain + 1.0f) +
-                           (gain - 1.0f) * cosf(w0) +
-                           2.0f * sqrtf(gain) * alpha;
-            filter->a[1] = -2.0f * ((gain - 1.0f) +
-                           (gain + 1.0f) * cosf(w0));
-            filter->a[2] = (gain + 1.0f) +
-                           (gain - 1.0f) * cosf(w0) -
-                           2.0f * sqrtf(gain) * alpha;
+            alpha = sinf(w0)/2.0f*sqrtf((gain + 1.0f/gain)*(1.0f/0.75f - 1.0f) + 2.0f);
+            filter->b[0] =       gain*((gain+1.0f) - (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha);
+            filter->b[1] =  2.0f*gain*((gain-1.0f) - (gain+1.0f)*cosf(w0)                         );
+            filter->b[2] =       gain*((gain+1.0f) - (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha);
+            filter->a[0] =             (gain+1.0f) + (gain-1.0f)*cosf(w0) + 2.0f*sqrtf(gain)*alpha;
+            filter->a[1] = -2.0f*     ((gain-1.0f) + (gain+1.0f)*cosf(w0)                         );
+            filter->a[2] =             (gain+1.0f) + (gain-1.0f)*cosf(w0) - 2.0f*sqrtf(gain)*alpha;
             break;
         case ALfilterType_Peaking:
             alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));