git.y1.nz

commit dec16ab22e9be54fe91332488ae76ab01eabcfab
parent 853c89d2964920f04bf73ab96d316f35b5f2912c
Author: Tempestro <112181066+Tempestro@users.noreply.github.com>
Date:   Sat, 25 May 2024 20:21:03 +0200

Mention that HIDE_BKG/SHOW_BKG don't work on CGB

Adds a mention to the docs that HIDE_BKG and SHOW_BKG do not work while running in CGB mode, the relevant bit instead overrides all background/window priority over the sprite layer, see Pandocs 4.4

Diffstat:
M
gbdk-lib/include/gb/gb.h
12
++++++++++++

1 file changed, 12 insertions(+), 0 deletions(-)
diff --git a/gbdk-lib/include/gb/gb.h b/gbdk-lib/include/gb/gb.h
@@ -890,12 +890,24 @@ void hiramcpy(uint8_t dst, const void *src, uint8_t n) OLDCALL PRESERVES_REGS(b,
 
 /** Turns on the background layer.
     Sets bit 0 of the LCDC register to 1.
+
+    Doesn't work in CGB mode - the bit is reused to control sprite priority
+    over background and window layers instead.
+    If 1 @ref (SHOW_BKG), everything works as usual.
+    If 0 @ref (HIDE_BKG), all sprites are always drawn over background and window,
+    ignoring any other priority settings.
 */
 #define SHOW_BKG \
   LCDC_REG|=LCDCF_BGON
 
 /** Turns off the background layer.
     Sets bit 0 of the LCDC register to 0.
+
+    Doesn't work in CGB mode - the bit is reused to control sprite priority
+    over background and window layers instead.
+    If 1 @ref (SHOW_BKG), everything works as usual.
+    If 0 @ref (HIDE_BKG), all sprites are always drawn over background and window,
+    ignoring any other priority settings.
 */
 #define HIDE_BKG \
   LCDC_REG&=~LCDCF_BGON

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