Add support for a level having more than one associated landmark, for levels with alternative starting points (#12)

constants/landmark_constants.asm

@@ -1,21 +1,21 @@
-; Landmarks indexes (see data/maps/landmarks.asm)
+; Landmarks indexes (see data/level_selection_menu.asm)
 	const_def
 	const LANDMARK_LEVEL_1           ; 00
 if DEF(_DEBUG)
-	const LANDMARK_DEBUGLEVEL_1      ; 00
+	const LANDMARK_DEBUGLEVEL_1      ; 01
-	const LANDMARK_DEBUGLEVEL_2      ; 01
+	const LANDMARK_DEBUGLEVEL_2      ; 02
-	const LANDMARK_DEBUGLEVEL_3      ; 02
+	const LANDMARK_DEBUGLEVEL_3      ; 03
-	const LANDMARK_DEBUGLEVEL_4      ; 03
+	const LANDMARK_DEBUGLEVEL_4      ; 04
-	const LANDMARK_DEBUGLEVEL_5      ; 04
+	const LANDMARK_DEBUGLEVEL_5      ; 05
 endc
 DEF NUM_LANDMARKS EQU const_value
 
-; used in CaughtData
+; used in CaughtData (legacy)
 	const_def $7f, -1
 	const LANDMARK_EVENT             ; $7f
 	const LANDMARK_GIFT              ; $7e
 
-; Regions
+; Regions (legacy)
 	const_def
 	const JOHTO_REGION ; 0
 	const KANTO_REGION ; 1

constants/level_constants.asm

@@ -0,0 +1,11 @@
+; Level indexes (see data/level_selection_menu.asm)
+	const_def
+	const LEVEL_1           ; 00
+if DEF(_DEBUG)
+	const DEBUGLEVEL_1      ; 01
+	const DEBUGLEVEL_2      ; 02
+	const DEBUGLEVEL_3      ; 03
+	const DEBUGLEVEL_4      ; 04
+	const DEBUGLEVEL_5      ; 05
+endc
+DEF NUM_LEVELS EQU const_value

data/level_selection_menu.asm

@@ -17,6 +17,7 @@ MACRO level_selection_menu_landmark
 ENDM
 
 LevelSelectionMenu_Landmarks:
+	table_width 6, LevelSelectionMenu_Landmarks
 .landmark1
 	level_selection_menu_landmark 0, 16, 12, .Level1LandmarkName, SPAWN_LEVEL_1 ; LANDMARK_LEVEL_1
 .landmark2
@@ -27,6 +28,7 @@ if DEF(_DEBUG)
 	level_selection_menu_landmark 1, 16, 11, .DebugLevel4LandmarkName, SPAWN_DEBUGLEVEL_4 ; LANDMARK_DEBUGLEVEL_4
 	level_selection_menu_landmark 2,  9,  5, .DebugLevel5LandmarkName, SPAWN_DEBUGLEVEL_5 ; LANDMARK_DEBUGLEVEL_5
 endc
+	assert_table_length NUM_LANDMARKS
 
 .Level1LandmarkName: db "LEVEL 1@"
 if DEF(_DEBUG)
@@ -108,3 +110,17 @@ LevelSelectionMenu_PageGrid:
 
 DEF LEVELSELECTIONMENU_PAGE_GRID_WIDTH  EQU 4
 DEF LEVELSELECTIONMENU_PAGE_GRID_HEIGHT EQU 4
+
+LandmarkToLevelTable:
+; the usual level:landmark relation is expected to be 1:1, but 1:n is
+; also supported, for levels that may have alternative starting points.
+	table_width 1, LandmarkToLevelTable
+	db LEVEL_1 ; LANDMARK_LEVEL_1
+if DEF(_DEBUG)
+	db DEBUGLEVEL_1 ; LANDMARK_DEBUGLEVEL_1
+	db DEBUGLEVEL_2 ; LANDMARK_DEBUGLEVEL_2
+	db DEBUGLEVEL_3 ; LANDMARK_DEBUGLEVEL_3
+	db DEBUGLEVEL_4 ; LANDMARK_DEBUGLEVEL_4
+	db DEBUGLEVEL_5 ; LANDMARK_DEBUGLEVEL_5
+endc
+	assert_table_length NUM_LANDMARKS

engine/menus/intro_menu.asm

@@ -23,6 +23,8 @@ if DEF(_DEBUG)
 	ld a, 100
 	ld [wCurPartyLevel], a
 	predef TryAddMonToParty
+	ld a, -1
+	ld [wUnlockedLevels], a ; debug
 endc
 	farcall AutoSaveGameOutsideOverworld
 	jp GameMenu

engine/menus/level_selection_menu.asm

@@ -4,8 +4,6 @@ LevelSelectionMenu::
 	ldh [hMapAnims], a
 	ld a, 1 << 2 ; do not clear wShadowOAM during DoNextFrameForAllSprites
 	ld [wVramState], a
-	ld a, -1
-	ld [wUnlockedLevels], a ; debug
 
 	call ClearBGPalettes
 	call ClearTilemap
@@ -598,6 +596,12 @@ LevelSelectionMenu_GetValidDirections:
 ; the landmark byte of this transition is two bytes back
 	dec hl
 	dec hl
+; use LandmarkToLevelTable to find the level that this landmark belongs to
+	ld e, [hl]
+	ld d, 0
+	ld hl, LandmarkToLevelTable
+	add hl, de
+; find if said level has been unlocked
 	ld e, [hl]
 	ld b, CHECK_FLAG
 	call UnlockedLevelsFlagAction

includes.asm

@@ -40,6 +40,7 @@ INCLUDE "constants/engine_flags.asm"
 INCLUDE "constants/event_flags.asm"
 INCLUDE "constants/icon_constants.asm"
 INCLUDE "constants/landmark_constants.asm"
+INCLUDE "constants/level_constants.asm"
 INCLUDE "constants/map_constants.asm"
 INCLUDE "constants/map_data_constants.asm"
 INCLUDE "constants/map_object_constants.asm"