use sound panning constants in battle_anim_scripts

include/battle_anim.h

@@ -31,9 +31,6 @@ struct BattleAnimBackground
 
 #define ANIM_ARGS_COUNT 8
 
-#define PAN_SIDE_PLAYER     -64
-#define PAN_SIDE_OPPONENT   63
-
 extern void (*gAnimScriptCallback)(void);
 extern bool8 gAnimScriptActive;
 extern u8 gAnimVisualTaskCount;

include/constants/battle_anim.h

@@ -7,6 +7,20 @@
 #define ANIM_ATK_PARTNER 2
 #define ANIM_DEF_PARTNER 3
 
+// stereo panning constants [0-255]
+//
+//          0
+//         .  .
+//      .        .
+// 192 .          . 63
+//     .          .
+//      .        .
+//         .  .
+//          127
+//  
+#define SOUND_PAN_ATTACKER -64
+#define SOUND_PAN_TARGET    63
+
 // move background ids
 #define BG_DARK_ 0 // the same as BG_DARK but is unused
 #define BG_DARK 1