From: Lukas Krickl <lukas@krickl.dev>
Date: Thu, 21 Aug 2025 13:47:19 +0000 (+0200)
Subject: mapgen: wip door generator
X-Git-Url: https://git.krickl.dev/?a=commitdiff_plain;h=0c5852ca0cc6fbfadc6ec220e77835bd7e84ff6a;p=gbrg%2F.git

mapgen: wip door generator
---

diff --git a/src/mapgen.s b/src/mapgen.s
index c56b0b0..a03a085 100644
--- a/src/mapgen.s
+++ b/src/mapgen.s
@@ -142,18 +142,186 @@ mapgen:
   ret
 	
 	; generates door locations for each map
+	; starts at location 3/3 and moves one door at a time
+	; avoids placing doors at the edge.
+	; stops after plaving at least N  doors
 mapgen_make_doors:
-	ld a, FLOOR_MAP_COUNT
-	ld hl, map_doors_location
-	; TODO: fnor now just place all 4 doors
+	ld b, 3
+	ld c, 3 ; bc = y/x position
+	; start current ptr at 1/1 as well
+	ld hl, map_doors_location + 1  * FLOOR_W 
+
+	; set map cursor
+	ld a, 1 + FLOOR_W
+	ld [player_map_cursor], a
+	
+	; select how many doors we want
+	push bc
+	push hl
+	call rand
+	add a, FLOOR_MAP_COUNT * 2 ; at least N doors
+	and a, (FLOOR_MAP_COUNT - 1) * 4
+
+	pop hl
+	pop bc
+
 @loop:
 		push af
-		ld a, DIRUP | DIRDOWN | DIRLEFT | DIRRIGHT
-		ld [hl+], a
+		push hl
+		push bc
+
+		; select a random location
+
+		call rand
+		and a, 3 
+
+		pop bc
+		pop hl
+		
+		call make_door
+		cp a, 0xFF
+		jp z, @loop ; try again
+		call make_opp_door
+
 		pop af
 		dec a
 		jr nz, @loop REL
 	ret
+	
+	; creates the counterpart to 
+	; a recently created door
+	;	inputs:
+	;		a: 1 = UP, 2 = DOWN, 3 = LEFT, 0 = RIGHT
+	;		[hl]: current door ptr
+	;	returns:
+	;		[hl]: ord new door
+make_opp_door:
+	cp a, 0
+	jp z, @right
+	cp a, 1
+	jp z, @up
+	cp a, 2
+	jp z, @down
+	cp a, 3
+	jp z, @left
+
+@right:	
+	ld a, [hl]
+	or a, DIRLEFT 
+	ld [hl], a
+	ret
+@up:	
+	ld a, [hl]
+	or a, DIRDOWN
+	ld [hl], a
+	ret
+@down:
+	ld a, [hl]
+	or a, DIRUP
+	ld [hl], a
+	ret
+@left:
+	ld a, [hl]
+	or a, DIRRIGHT
+	ld [hl], a
+	ret
+
+	; creates a single door
+	; based on the random selection
+	; inputs:
+	;		a: 1 = UP, 2 = DOWN, 3 = LEFT, 0 = RIGHT
+	;		bc: current coordinate
+	;		hl: current ptr
+	;	returns:
+	;		a: FF -> unable to place door
+	;		a: door direction -> door placed
+	;		[hl]: ors new door bit
+	;		bc: if door placed moves coordinates
+	;		hl: if door placed moves ptr
+make_door:
+	push af
+	cp a, 0 
+	jp z, @right
+
+	cp a, 1
+	jp z, @up
+
+	cp a, 2
+	jp z, @down
+
+	cp a, 3
+	jp z, @left
+
+@try_again:
+	pop af
+	; try again...
+	ld a, 0xFF
+	ret
+@right: 
+	
+	; can we even place it?
+	ld a, c
+	cp a, 0
+	jp z, @try_again
+
+	; we can!
+	ld a, [hl]
+	or a, DIRRIGHT
+	ld [hl], a
+
+	dec c ; x--
+	dec hl ; hl--
+
+	pop af
+	ret
+@left:
+	ld a, c
+	cp a, MAP_W-1
+	jp z, @try_again
+
+	ld a, [hl]
+	or a, DIRLEFT
+	ld [hl], a
+	
+	inc c ; x++
+	inc hl ; hl++
+
+	pop af
+	ret
+@up:
+	
+	ld a, b
+	cp a, 0
+	jp z, @try_again
+
+	ld a, [hl]
+	or a, DIRUP
+	ld [hl], a
+
+	dec b ; y--
+
+	ld de, -FLOOR_W & 0xFFFF
+	add hl, de ; hl one row up
+
+	pop af
+	ret
+@down:
+	
+	ld a, b
+	cp a, MAP_H-1
+	jp z, @try_again
+
+	ld a, [hl]
+	or a, DIRDOWN
+	ld [hl], a
+
+	inc bc ; y++
+
+	ld de, FLOOR_W
+	add hl, de ; hl one row downa
+
+	pop af
+	ret
 
 	; loads the current player map cursor 
 	; and draws the required doors