A classic use for blitting is to render transparent sprites onto a background. In this example a background image, a sprite, and a 1-bit mask are used.

 
 
 
 PROCEDURE example ON ALL BUT VIC20, VG5000
 
 	BITMAP ENABLE(16)
 	
 	DEFINE PALETTE NOT PRESERVE
 	
 	CLS BLACK
 	
 	mask := LOAD IMAGE("blit_mask.png") EXACT TRANSPARENCY BLACK OPACITY LIGHT WHITE
 	background := LOAD IMAGE("blit_background.png")
 	sprite := LOAD IMAGE("blit_sprite.png")
 	
 	CONST x = ( SCREEN WIDTH - IMAGE WIDTH(background) ) \ #2
 	CONST y = ( SCREEN HEIGHT - IMAGE HEIGHT(background) ) \ #2
 	
 	PUT IMAGE background AT x,y
 	
 	REM In the first blit, the mask is blitted onto the background using 
 	REM the raster operator AND. Because any value ANDed with 0 equals 0, 
 	REM and any value ANDed with 1 is unchanged, black areas are created 
 	REM where the actual sprites will appear, while leaving the rest of 
 	REM the background alone.
 	
 	BLIT bop1 AS ( ( SOURCE ) AND ( DESTINATION ) )
 	BLIT IMAGE mask AT x+10,y+10 WITH bop1
 	
 	REM In the second blit, the sprite is blitted onto the newly altered 
 	REM background using the raster operator of OR. Because any value 
 	REM ORed with 0 is unchanged, the background is unaffected and the 
 	REM black areas are filled with the actual sprite image.
 	
 	BLIT bop2 AS ( ( ( INVERSE ( SOURCE 2 ) ) AND ( SOURCE 1 ) ) OR ( DESTINATION ) )
 	BLIT IMAGES sprite, mask AT x+10,y+10 WITH bop2
 	
 END PROC
 
 CALL example ON ALL BUT VIC20, VG5000
 	
 	
 	
 

• blit_basic_mask.bas

The instructions here refer to compiling the example from the command line. For Microsoft Windows users we suggest using UGBASIC-IDE, which allows you to compile the example with just one click.

In order to compile and run the example, you need to have the Altirra emulator, and in particular that the altirra executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.atari blit_basic_mask.bas -o example.xex
 altirra example.xex
 
 # Windows 
 ugbc.atari.exe blit_basic_mask.bas -o example.xex
 altirra example.xex

In order to compile and run the example, you need to have the Altirra emulator, and in particular that the altirra executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.atarixl blit_basic_mask.bas -o example.xex
 altirra example.xex
 
 # Windows 
 ugbc.atarixl.exe blit_basic_mask.bas -o example.xex
 altirra example.xex

In order to compile and run the example, you need to have the VICE emulator, and in particular that the x64sc executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.c64 blit_basic_mask.bas -o example.prg
 x64sc example.prg
 
 # Windows 
 ugbc.c64.exe blit_basic_mask.bas -o example.prg
 x64sc example.prg

In order to compile and run the example, you need to have the VICE emulator, and in particular that the x64sc executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.c64reu blit_basic_mask.bas -o example.prg
 x64sc -reu example.prg
 
 # Windows 
 ugbc.c64reu.exe blit_basic_mask.bas -o example.prg
 x64sc -reu example.prg

In order to run the example, you need to have the YAPE emulator. In particular that the yape executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.plus4 blit_basic_mask.bas -o example.prg
 yape example.prg
 
 # Windows 
 ugbc.plus4.exe blit_basic_mask.bas -o example.prg
 yape example.prg

In order to run the example, you need to have the VICE emulator. In particular that the xplus4 executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.plus4 blit_basic_mask.bas -o example.prg
 xplus4 example.prg
 
 # Windows 
 ugbc.plus4.exe blit_basic_mask.bas -o example.prg
 xplus4 example.prg

In order to compile and run the example, you need to have the XROAR emulator, and in particular that the xroar executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.d32 blit_basic_mask.bas -o example.bin
 xroar -rompath (your rom path) example.bin
 
 # Windows 
 ugbc.d32.exe blit_basic_mask.bas -o example.bin
 xroar.exe -rompath (your rom path) example.bin

In order to compile and run the example, you need to have the XROAR emulator, and in particular that the xroar executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.d64 blit_basic_mask.bas -o example.bin
 xroar -rompath (your rom path) example.bin
 
 # Windows 
 ugbc.d64.exe blit_basic_mask.bas -o example.bin
 xroar.exe -rompath (your rom path) example.bin

In order to compile and run the example, you need to have the DCMOTO emulator, and in particular that the dcmoto executable is accessible.

Then, type this command on the command line and on the emulator:

 # Linux 
 ugbc.pc128op blit_basic_mask.bas -o example.k7
 dcmoto
 (choose BASIC 128)
 CLEAR,&H2FFF: LOADM"CASS:",R: EXEC
 
 # Windows 
 ugbc.pc128op.exe blit_basic_mask.bas -o example.k7
 dcmoto
 (choose example.k7)
 (choose BASIC 128)
 CLEAR,&H2FFF: LOADM"CASS:",R: EXEC

In order to compile and run the example, you need to have the DCMOTO emulator, and in particular that the dcmoto executable is accessible.

Then, type this command on the command line and on the emulator:

 # Linux 
 ugbc.pc128op blit_basic_mask.bas -o example.k7
 dcmoto
 (choose BASIC 128)
 CLEAR,&H2FFF: LOADM"CASS:",R: EXEC
 
 # Windows 
 ugbc.pc128op.exe blit_basic_mask.bas -o example.k7
 dcmoto
 (choose example.k7)
 (choose BASIC 128)
 CLEAR,&H2FFF: LOADM"CASS:",R: EXEC

In order to compile and run the example, you need to have the VICE emulator, and in particular that the xvic executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.vic20 blit_basic_mask.bas -o example.prg
 xvic --memory 24k example.prg
 
 # Windows 
 ugbc.vic20.exe blit_basic_mask.bas -o example.prg
 xvic --memory 24k example.prg

In order to compile and run the example, you need to have the Speccy emulator, and in particular that the speccy executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.zx blit_basic_mask.bas -o example.tap
 Speccy example.tap
 
 # Windows 
 ugbc.zx.exe blit_basic_mask.bas -o example.tap
 Speccy example.tap

In order to compile and run the example, you need to have the openMsx or the BlueMSX emulator, and in particular that its executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.msx1 blit_basic_mask.bas -o example.rom
 openmsx -cart example.rom
 
 # Windows 
 ugbc.msx1.exe blit_basic_mask.bas -o example.rom
 openmsx -cart example.rom

 # Linux 
 ugbc.msx1 blit_basic_mask.bas -o example.rom
 bluemsx example.rom
 
 # Windows 
 ugbc.msx1.exe blit_basic_mask.bas -o example.rom
 bluemsx example.rom

In order to compile and run the example, you need to have the openMsx or the BlueMSX emulator, and in particular that its executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.coleco blit_basic_mask.bas -o example.rom
 openmsx -machine \"COL - ColecoVision\" -cart example.rom
 
 # Windows 
 ugbc.coleco.exe blit_basic_mask.bas -o example.rom
 bluemsx -machine \"COL - ColecoVision\" example.rom

 # Linux 
 ugbc.coleco blit_basic_mask.bas -o example.rom
 bluemsx /machine \"COL - ColecoVision\" /rom1 example.rom
 
 # Windows 
 ugbc.coleco.exe blit_basic_mask.bas -o example.rom
 bluemsx  /machine \"COL - ColecoVision\" /rom1 example.rom

In order to compile and run the example, you need to have the BlueMSX emulator, and in particular that its executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.sc3000 blit_basic_mask.bas -o example.rom
 bluemsx /machine \"SEGA - SC-3000\" /rom1 example.rom
 
 # Windows 
 ugbc.sc3000.exe blit_basic_mask.bas -o example.rom
 bluemsx  /machine \"SEGA - SC-3000\" /rom1 example.rom

In order to compile and run the example, you need to have the BlueMSX emulator, and in particular that its executable is accessible.

Then, type this command on the command line:

 # Linux 
 ugbc.sg1000 blit_basic_mask.bas -o example.rom
 bluemsx /machine \"SEGA - SG-1000\" /rom1 example.rom
 
 # Windows 
 ugbc.sg1000.exe blit_basic_mask.bas -o example.rom
 bluemsx  /machine \"SEGA - SG-1000\" /rom1 example.rom

If you have found a problem trying to run this example, if you think there is a bug or, more simply, you would like it to be improved, open an issue for this example on GitHub. Thank you!