Figure 59 - The Bldcnt Register - Nintendo GAME BOY ADVANCE Programming Manual

May 25, 2005
9 Color Special Effects
The Game Boy Advance provides the following color special effects. The area where these effects are
applied can be limited using a window.
1. Blending
α
Performs arithmetic operations on 2 selected surfaces and implements processing for 16 levels of
semi-transparency.
2. Fade-in/Fade-out
Performs arithmetic operations on 1 selected surface and implements processing for 16 levels of
brightness.
9.1 Selection of Color Special Effects
The types of color special effects and the target pixels, are determined by the BLDCNT register.
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Address Register
050h BLDCNT
Although color special effects are specif ied by the BLDCNT register, for
cessing between surfaces, the 2 target surfaces must have suitable priorities.
© 1999-2005 NINTENDO
Figure 59 - The BLDCNT Register
BD OBJBG3BG2BG1BG0
2nd Target Pixel
Attributes Initial Value
BD OBJ BG3 BG2 BG1 BG0 R/W
1st Target Pixel
Color Special Effects Setting
blending, which involves pro-
α
AGB-06-0001-002-B13
Released: May 27, 2005
67
0000h