Fix misc 10 (#1208)

* Cleanup around `Item_DropCollectible`

* Cleanup around `Math3D_Vec3fDistSq`, `Math3D_Dist2DSq`

* Material/Model naming for one dlist pair

* Minor comments fixup

* Explicit `!= NULL` check

* Signed decimal for an array of coordinates

* Fixup comments some more

include/z64actor.h

@@ -9,8 +9,8 @@
 #define ACTOR_NUMBER_MAX 200
 #define INVISIBLE_ACTOR_MAX 20
 #define AM_FIELD_SIZE 0x27A0
-#define MASS_IMMOVABLE 0xFF // Cannot be pushed by OC collisions
-#define MASS_HEAVY 0xFE // Can only be pushed by OC collisions with IMMOVABLE and HEAVY objects.
+#define MASS_IMMOVABLE 0xFF // Cannot be pushed by OC colliders
+#define MASS_HEAVY 0xFE // Can only be pushed by OC colliders from actors with IMMOVABLE or HEAVY mass.
 
 struct Actor;
 struct GlobalContext;
@@ -266,6 +266,7 @@ typedef enum {
     /* 0x17 */ ITEM00_TUNIC_ZORA,
     /* 0x18 */ ITEM00_TUNIC_GORON,
     /* 0x19 */ ITEM00_BOMBS_SPECIAL,
+    /* 0x1A */ ITEM00_MAX,
     /* 0xFF */ ITEM00_NONE = 0xFF
 } Item00Type;
 

include/z64collision_check.h

@@ -195,7 +195,7 @@ typedef struct {
     /* 0x00 */ Vec3f quad[4];
     /* 0x30 */ Vec3s dcMid; // midpoint of vectors d, c
     /* 0x36 */ Vec3s baMid; // midpoint of vectors b, a
-    /* 0x3C */ f32 acDist; // distance to nearest AC collision this frame.
+    /* 0x3C */ f32 acDistSq; // distance to nearest AC collision this frame, squared.
 } ColliderQuadDim; // size = 0x40
 
 typedef struct {