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smooth scroll

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This commit is contained in:
Irmen de Jong 2020-03-24 02:42:32 +01:00
parent 3881ebe429
commit 11e9539416
2 changed files with 26 additions and 8 deletions
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3
compiler/res/prog8lib/c64utils.p8
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@ -593,6 +593,9 @@ asmsub scroll_left_full (ubyte alsocolors @ Pc) clobbers(A, Y) {
; ---- scroll the whole screen 1 character to the left
; contents of the rightmost column are unchanged, you should clear/refill this yourself
; Carry flag determines if screen color data must be scrolled too
; TODO why are the two inner loops split apart? can't they just be one single .for/.next macro?
%asm {{
stx c64.SCRATCH_ZPREGX
bcs +

31
examples/skramble.p8
View File

@ -7,10 +7,16 @@
main {
ubyte perform_scroll = false
sub start() {
c64scr.plot(30,2)
c64scr.print("skramble !")
c64.SCROLX = c64.SCROLX & %11110111 ; 38 column mode
c64utils.set_rasterirq(1) ; enable animation
ubyte target_height = 10
ubyte active_height = 25
@ -20,17 +26,21 @@ main {
} else if active_height > target_height {
active_height--
} else {
target_height = 10 + rnd() % 13
target_height = 8 + rnd() % 16
continue
}
while not perform_scroll {
; let the raster irq do its timing job
}
perform_scroll = false
c64scr.scroll_left_full(true)
ubyte yy
for yy in 0 to active_height-1 {
c64scr.setcc(39, yy, 32, 2)
c64scr.setcc(39, yy, 32, 2) ; clear top
}
for yy in active_height to 24 {
c64scr.setcc(39, yy, 102, 8)
c64scr.setcc(39, yy, 102, 8) ; draw mountain
}
yy = rnd()
@ -68,11 +78,16 @@ main {
; c64scr.setcc(1, 10, @'=', 15)
; c64scr.setcc(2, 10, @'>', 15)
for A in 0 to 4 {
while @($d012) != 100 {
; just wait for the raster beam...
}
}
}
}
}
irq {
ubyte smoothx=7
sub irq() {
smoothx = (smoothx-1) & 7
main.perform_scroll = smoothx==0
c64.SCROLX = (c64.SCROLX & %11111000) | smoothx
}
}