optimize ship offsets. add explosion sound. tweak pickup ranges.

src/game.c

 }
 
 static void show_explosion(uint16_t power) NONBANKED {
+    snd_explode();
+
     for (uint8_t n = 0; n < (4 * 4); n++) {
         uint8_t hiwater = SPR_NUM_START;
         spr_draw(SPR_EXPL, FLIP_NONE, 0, 0, n >> 2, &hiwater);
             }
 
             if (ret == OBJ_ADDED) {
-                snd_noise();
+                snd_shot();
             }
         }
 

src/obj.c

 
 #define GRAVITY_RANGE (24 << POS_SCALE_OBJS)
 #define GRAVITY_SHIFT (POS_SCALE_OBJS + 4)
+
 #define DAMAGE_RANGE (16 << POS_SCALE_OBJS)
 #define DAMAGE_INC 5
 
-#define PICKUP_SMALL_RANGE (10 << POS_SCALE_OBJS)
-#define PICKUP_LARGE_RANGE (18 << POS_SCALE_OBJS)
+#define HEALTH_RANGE (18 << POS_SCALE_OBJS)
+#define HEALTH_INC HEALTH_MAX
+
+#define PICKUP_SMALL_RANGE (12 << POS_SCALE_OBJS)
 #define SHOT_RANGE (10 << POS_SCALE_OBJS)
 
 #define SCORE_SMALL 5
                     }
                 }
 
-                if ((abs_off_x <= PICKUP_LARGE_RANGE) && (abs_off_y <= PICKUP_LARGE_RANGE)) {
-                    damage -= HEALTH_MAX;
+                if ((abs_off_x <= HEALTH_RANGE) && (abs_off_y <= HEALTH_RANGE)) {
+                    damage -= HEALTH_INC;
                 }
                 break;
 

src/sound.c

 #endif
 }
 
-void snd_noise(void) NONBANKED {
+void snd_shot(void) NONBANKED {
     NR41_REG = 0x2F; // length timer, higher value is shorter time (up to 0x3F)
     NR42_REG = 0xF0; // initially full volume, no volume changes over time
     NR43_REG = 0x11; // frequency distribution
     NR44_REG = 0xC0; // trigger and enable length
 }
+
+void snd_explode(void) NONBANKED {
+    NR41_REG = 0x00; // length timer, higher value is shorter time (up to 0x3F)
+    NR42_REG = 0xF1; // initially full volume, then fade sound out
+    NR43_REG = 0x46; // frequency distribution
+    NR44_REG = 0xC0; // trigger and enable length
+}

src/sound.h

 #define __SOUND_H__
 
 void snd_init(void);
-void snd_noise(void);
+void snd_shot(void);
+void snd_explode(void);
 
 #endif // __SOUND_H__

src/sprites.c

 void spr_ship(enum SPRITE_ROT rot, uint8_t moving, uint8_t *hiwater) NONBANKED {
     switch (rot) {
         case ROT_0:
-            spr_draw(SPR_SHIP, FLIP_NONE, 0, 4, moving ? 1 : 0, hiwater);
+            spr_draw(SPR_SHIP, FLIP_NONE, -1, 4, moving ? 1 : 0, hiwater);
             break;
 
         case ROT_45:
-            spr_draw(SPR_SHIP, FLIP_NONE, -4, 0, moving ? 3 : 2, hiwater);
+            spr_draw(SPR_SHIP, FLIP_NONE, -6, 0, moving ? 3 : 2, hiwater);
             break;
 
         case ROT_90:
-            spr_draw(SPR_SHIP, FLIP_NONE, -4, 0, moving ? 5 : 4, hiwater);
+            spr_draw(SPR_SHIP, FLIP_NONE, -4, -1, moving ? 5 : 4, hiwater);
             break;
 
         case ROT_135:
-            spr_draw(SPR_SHIP, FLIP_Y, -4, 0, moving ? 3 : 2, hiwater);
+            spr_draw(SPR_SHIP, FLIP_Y, -6, 0, moving ? 3 : 2, hiwater);
             break;
 
         case ROT_180:
-            spr_draw(SPR_SHIP, FLIP_Y, 0, -4, moving ? 1 : 0, hiwater);
+            spr_draw(SPR_SHIP, FLIP_Y, -1, -4, moving ? 1 : 0, hiwater);
             break;
 
         case ROT_225:
-            spr_draw(SPR_SHIP, FLIP_XY, 4, 0, moving ? 3 : 2, hiwater);
+            spr_draw(SPR_SHIP, FLIP_XY, 6, 0, moving ? 3 : 2, hiwater);
             break;
 
         case ROT_270:
-            spr_draw(SPR_SHIP, FLIP_X, 4, 0, moving ? 5 : 4, hiwater);
+            spr_draw(SPR_SHIP, FLIP_X, 4, -1, moving ? 5 : 4, hiwater);
             break;
 
         case ROT_315:
-            spr_draw(SPR_SHIP, FLIP_X, 4, 0, moving ? 3 : 2, hiwater);
+            spr_draw(SPR_SHIP, FLIP_X, 6, 0, moving ? 3 : 2, hiwater);
             break;
 
         default: