From f353c89172495f0916431c365260f45584b3b6ec Mon Sep 17 00:00:00 2001
From: Jorim Tielemans <tielemans.jorim@gmail.com>
Date: Wed, 31 Jul 2019 18:15:03 +0200
Subject: [PATCH] Add relative scroll to backgrounds

---
 engine/include/libgba-sprite-engine/background/background.h | 3 ++-
 engine/src/background/background.cpp                        | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/engine/include/libgba-sprite-engine/background/background.h b/engine/include/libgba-sprite-engine/background/background.h
index f55ae01..efcfcf1 100644
--- a/engine/include/libgba-sprite-engine/background/background.h
+++ b/engine/include/libgba-sprite-engine/background/background.h
@@ -25,9 +25,10 @@ public:
     const int getCharBlock() { return charBlockIndex; }
     void useMapScreenBlock(int block) { screenBlockIndex = block; }
     void scroll(int x, int y);
+    void scrollSpeed(int dx, int dy);
 
     Background(int bgIndex, const void *data, int size, const void* map, int mapSize) : data(data), bgIndex(bgIndex), size(size), map(map),
-                                                                       screenBlockIndex(0), charBlockIndex(0), mapSize(mapSize) {}
+                                                                                        screenBlockIndex(0), charBlockIndex(0), mapSize(mapSize) {}
     virtual void persist();
     void updateMap(const void* map);
     void clearMap();
diff --git a/engine/src/background/background.cpp b/engine/src/background/background.cpp
index f5121c5..3191005 100644
--- a/engine/src/background/background.cpp
+++ b/engine/src/background/background.cpp
@@ -78,4 +78,9 @@ void Background::buildRegister() {
 void Background::scroll(int x, int y) {
     REG_BG_OFS[bgIndex].x = x;
     REG_BG_OFS[bgIndex].y = y;
+}
+
+void Background::scrollSpeed(int dx, int dy) {
+    REG_BG_OFS[bgIndex].x += dx;
+    REG_BG_OFS[bgIndex].y += dy;
 }
\ No newline at end of file