Updated the intro

constants/hardware_constants.asm

@@ -22,14 +22,6 @@ JOYPAD   EQU 4
 
 LY_VBLANK EQU 145
 
-; OAM attribute flags
-OAM_PALETTE   EQU %111
-OAM_TILE_BANK EQU 3
-OAM_OBP_NUM   EQU 4 ; Non CGB Mode Only
-OAM_X_FLIP    EQU 5
-OAM_Y_FLIP    EQU 6
-OAM_PRIORITY  EQU 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)
-
 ; serial
 START_TRANSFER_EXTERNAL_CLOCK EQU $80
 START_TRANSFER_INTERNAL_CLOCK EQU $81

constants/misc_constants.asm

@@ -45,6 +45,8 @@ SCREEN_HEIGHT EQU 18
 SCREEN_WIDTH_PIXELS  EQU SCREEN_WIDTH * 8
 SCREEN_HEIGHT_PIXELS EQU SCREEN_HEIGHT * 8
 
+BYTES_PER_TILE EQU 16
+
 BG_MAP_WIDTH  EQU 32
 BG_MAP_HEIGHT EQU 32
 

constants/oam_constants.asm

@@ -5,5 +5,14 @@ OAMFLAG_VFLIPPED    EQU %00100000 ; OAM flag flips the sprite vertically.
 ; Used for making left facing sprites face right and to alternate between left and right foot animation when walking up or down
 
 ; OAM attribute flags
-OAM_HFLIP EQU %00100000 ; horizontal flip
-OAM_VFLIP EQU %01000000 ; vertical flip
+OAM_PALETTE   EQU %111
+OAM_TILE_BANK EQU 3
+OAM_OBP_NUM   EQU 4 ; Non CGB Mode Only
+OAM_X_FLIP    EQU 5
+OAM_Y_FLIP    EQU 6
+OAM_PRIORITY  EQU 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)
+
+; OAM attribute masks
+OAM_HFLIP     EQU 1 << OAM_X_FLIP ; horizontal flip
+OAM_VFLIP     EQU 1 << OAM_Y_FLIP ; vertical flip
+OAM_BEHIND_BG EQU 1 << OAM_PRIORITY ; behind bg (except color 0)

constants/palette_constants.asm

@@ -1,3 +1,10 @@
+; monochrome palette color ids
+	const_def
+	const WHITE
+	const LIGHT_GRAY
+	const DARK_GRAY
+	const BLACK
+
 SET_PAL_BATTLE_BLACK         EQU $00
 SET_PAL_BATTLE               EQU $01
 SET_PAL_TOWN_MAP             EQU $02