From: Lukas Krickl <lukas@krickl.dev>
Date: Sat, 4 Oct 2025 19:20:57 +0000 (+0200)
Subject: video: scrolls now happen on a per-pixel basis
X-Git-Url: https://git.krickl.dev/?a=commitdiff_plain;h=52c80b0095031e2230286924f127698655aef557;p=gbrg%2F.git

video: scrolls now happen on a per-pixel basis
map objects and draws happen every 16th scroll.
---

diff --git a/src/player.s b/src/player.s
index 5e751d3..b020e47 100644
--- a/src/player.s
+++ b/src/player.s
@@ -89,28 +89,35 @@ player_update:
 
 #define PLAYER_SPRITE_IDLE1 0x8D
 	
-	; if the player's real y position is over
-	; a certain value we should scroll the map
-	; if scrolling is allowed
-player_try_scroll_up:
-	; do not scroll if the scroll timer is enabled
+	; sets scroll unless scroll is diabled
+player_set_scroll:
+	; scroll can still be allowed to complete the next tile
+	; even if the scroll disable object is loaded
 	ld a, [scroll_timer]
-	cp a, 0
-	ret nz
+	cp a, MAP_ROW_H-1
+	jr z, @scroll_anyway REL
 
 	ld a, [game_flags]
 	and a, GPF_NO_SCROLL
-	ret nz ; no scroll allowed for now
+	ret nz
+
+@scroll_anyway:
+	ld a, [game_flags]
+	or a, GPF_SCROLL
+	ld [game_flags], a
+	ret
 	
+	; if the player's real y position is over
+	; a certain value we should scroll the map
+	; if scrolling is allowed
+player_try_scroll_up:
 	ld a, [player_next_scroll_y]
 	ld b, a 
 	ld a, [player+act_pos_y]
 	cp a, b
 	jp nc, @no_scroll
 
-		ld a, [game_flags]
-		or a, GPF_SCROLL
-		ld [game_flags], a
+		call player_set_scroll
 		
 		; run next objects
 		; so they are loaded before a move is attempted
diff --git a/src/update.s b/src/update.s
index 9ae0149..d44be69 100644
--- a/src/update.s
+++ b/src/update.s
@@ -5,7 +5,6 @@ update_game:
   ; tick rng every frame
   call rand
 
-	
 	call video_map_adjust_scroll
 
 	call player_draw
diff --git a/src/video.s b/src/video.s
index 833dafb..7e5646b 100644
--- a/src/video.s
+++ b/src/video.s
@@ -38,29 +38,31 @@ vblank:
 	; loads a new map row and sets the scroll
 	; timer
 video_map_perform_scroll:
-	ld a, [game_flags]
-	and a, GPF_SCROLL
-	ret z
+	ld a, [scroll_timer]
+	cp a, MAP_ROW_H-1 
+	ret nz
 
-	call map_advance_row
+	xor a, a
+	ld [scroll_timer], a
 
-	; unset flag
-	ld a, [game_flags]
-	and a, ~GPF_SCROLL & 0xFF
-	ld [game_flags], a
+	call map_advance_row
 
-	ld a, MAP_ROW_H 
-	ld [scroll_timer], a
 	ret
 	
 	; adjusts the scroll slowly 1 pixel each frame
 	; until the timer reaches 0
 video_map_adjust_scroll:
-	ld a, [scroll_timer]
-	cp a, 0
+	ld a, [game_flags]
+	and a, GPF_SCROLL
 	ret z
 
-	dec a
+	; unset flag
+	ld a, [game_flags]
+	and a, ~GPF_SCROLL & 0xFF
+	ld [game_flags], a
+	
+	ld a, [scroll_timer]
+	inc a
 	ld [scroll_timer], a
 
 	ld a, [scroll_y]