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Flavioweb
Registered: Nov 2011
Posts: 463 |
Sprites over rasterbars: where?
Someone can tell me a demo/intro name where are sprites movin' over rasterbars?
Or, at least, sprites without movement over rasterbars?
Tnx. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Real DYSP |
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iAN CooG
Registered: May 2002
Posts: 3187 |
Dingy
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Zaz
Account closed
Registered: Mar 2004
Posts: 33 |
This Is What It Is |
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ready.
Registered: Feb 2003
Posts: 441 |
a part of this demo:
20 Minutes in the Future |
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raven
Account closed
Registered: Jan 2002
Posts: 137 |
Continuing what Skate has started, there's a 3rd method which is easiest to implement & also most versatile, as it basically takes care of itself.
Use a timer to count down from 63 and branch according to its value. This code must be done each line.
If you'd like bad-lines active, they'll require different handling.
The line code will look something like this:
lda #cycles
sbc $dd04
sta *+4
bcs *
lda #$a9
lda #$a9
...
bit $ea
...rest of raster code...
+ Sprites can be moved freely without restrictions, no update of the timings is required for non bad-lines
- Doesn't leave much raster-time per line |
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Trash
Registered: Jan 2002
Posts: 122 |
Another simple solution if you dont want graphics behind the sprites is:
outer_loop:
lda #raster_row
ldx #count_rows
cmp $d012
bne * - 3
inner_loop:
lda coltable, x
sta $d020
sta $d021
lda $d011
and #7
ora #16
sta $d011
dex
bne inner_loop
; move sprites around here
jmp outer_loop |
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Oswald
Registered: Apr 2002
Posts: 5086 |
or you can do it as Ninja, set a CIA timer to count down from 63 & set the irq vector over the CIA timer & set the register before to jump instruction $4c, and it will select the routine needed for the desired timing automagically. Beware, this eplanation is very rough, just added to drop in the idea. |
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