The following example displays the spaceship sprite and then redisplays it as a different
object. Only the sprite data list is affected, so only the data list is shown here. However,
the sprite looks best with the color registers set as shown in the
xample.
LEA CUSTOM,a0
MOVE.W #$0F00,COLOR17(a0) ; Color 17 red
MOVE.W #$0FF0,COLOR18(a0) ; Color 18 yellow
MOVE.W #$0FFF,COLORl9(a0) ; Color 19 white
SPRITE:
DC.W $6D60,$7200
DC.W $0990,$07E0
DC.W $13C8,$0FF0
DC.W $23C4,$1FF8
DC.W $13C8,$0FF0
DC.W $0990,$07E0
DC.W $8080,$8D00 ; VSTART, HSTART, VSTOP for new sprite
DC.W $1818,$0000
DC.W $7E7E,$0000
DC.W $7FFE,$0000
DC.W $FFFF,$2000
DC.W $FFFF,$2000
DC.W $FFFF,$3000
DC.W $FFFF,$3000
DC.W $7FFE,$1800
DC.W $7FFE,$0C00
DC.W $3FFC,$0000
DC.W $0FF0,$0000
DC.W $03C0,$0000
DC.W $0180,$ÿ0000
DC.W $0000,$0000 ; End of sprite data
OVERLAPPED SPRITES
For more complex or larger moving objects, you can overlap sprites. Overlapping simply
mean that the sprites have the same or relatively close screen positions. A relatively close
screen position can result in an object that is wider than 16 pixels.
The built-in sprite video priority ensures that one sprite appears to be behind the other
when sprites are overlapped. The priority circuitry gives the lowest-numbered sprite the
highest priority and the highest numbered sprite the lowest priority. Therefore, when
designing displays with overlapped sprites, make sure the "foreground" sprite has a lower
number than the "background" sprite. In Figure 4-11, for example, the cage should be
generated by a lower-numbered sprite DMA channel than the monkey.
- Sprite Hardware 115 -
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