prog8/examples/c64/balloonflight.p8
Irmen de Jong 08ac459a41 breaking change: sys.set_irq() and sys.set_rasterirq() no longer have useKernal parameter! The irq handler routine must return a boolean instead in the A register.
When it returns true it means run the system IRQ handler afterwards. When it returns false, the system handler is NOT ran afterwards.
2023-11-21 23:22:53 +01:00

141 lines
4.6 KiB
Lua

%import syslib
%import textio
%import math
%import test_stack
%zeropage basicsafe
; note: The flickering in the scrolling is caused by the CPU requiring
; too long to scroll the characters + the colors in course scroll.
; This takes nearly a full frame to accomplish, and causes tearing.
; It's very difficult to remove this flicker: it requires double buffering
; and splitting the coarse character scrolling on multiple phases...
main {
ubyte perform_scroll = false
sub start() {
c64.set_sprite_ptr(0, $0f00) ; alternatively, set directly: c64.SPRPTR[0] = $0f00 / 64
c64.SPENA = 1
c64.SP0COL = 14
c64.SPXY[0] = 80
c64.SPXY[1] = 100
c64.SCROLX &= %11110111 ; 38 column mode
sys.set_rasterirq(&irq.irqhandler, 200) ; enable animation via raster interrupt
ubyte target_height = 10
ubyte active_height = 24
bool upwards = true
repeat {
;txt.plot(0,0)
;test_stack.test()
ubyte mountain = 223 ; slope upwards
if active_height < target_height {
active_height++
upwards = true
} else if active_height > target_height {
mountain = 233 ; slope downwards
active_height--
upwards = false
} else {
target_height = 8 + math.rnd() % 16
if upwards
mountain = 233
else
mountain = 223
}
while not perform_scroll {
; let the raster irq do its timing job
}
perform_scroll = false
txt.scroll_left(true)
; float the balloon
if math.rnd() & %10000
c64.SPXY[1] ++
else
c64.SPXY[1] --
ubyte yy
for yy in 0 to active_height-1 {
txt.setcc(39, yy, 32, 2) ; clear top of screen
}
txt.setcc(39, active_height, mountain, 8) ; mountain edge
for yy in active_height+1 to 24 {
txt.setcc(39, yy, 160, 8) ; draw mountain
}
yy = math.rnd()
if yy > 100 {
; draw a star
txt.setcc(39, yy % (active_height-1), '.', math.rnd())
}
if yy > 200 {
; draw a tree
ubyte tree = 30
ubyte treecolor = 5
if yy & %01000000 != 0
tree = 88
else if yy & %00100000 != 0
tree = 65
if math.rnd() > 130
treecolor = 13
txt.setcc(39, active_height, tree, treecolor)
}
if yy > 235 {
; draw a camel
txt.setcc(39, active_height, 94, 9)
}
}
}
}
spritedata $0f00 {
; this memory block contains the sprite data
; it must start on an address aligned to 64 bytes.
%option force_output ; make sure the data in this block appears in the resulting program
ubyte[] balloonsprite = [ %00000000,%01111111,%00000000,
%00000001,%11111111,%11000000,
%00000011,%11111111,%11100000,
%00000011,%11100011,%11100000,
%00000111,%11011100,%11110000,
%00000111,%11011101,%11110000,
%00000111,%11011100,%11110000,
%00000011,%11100011,%11100000,
%00000011,%11111111,%11100000,
%00000011,%11111111,%11100000,
%00000010,%11111111,%10100000,
%00000001,%01111111,%01000000,
%00000001,%00111110,%01000000,
%00000000,%10011100,%10000000,
%00000000,%10011100,%10000000,
%00000000,%01001001,%00000000,
%00000000,%01001001,%00000000,
%00000000,%00111110,%00000000,
%00000000,%00111110,%00000000,
%00000000,%00111110,%00000000,
%00000000,%00011100,%00000000 ]
}
irq {
ubyte smoothx=0
sub irqhandler() -> bool {
smoothx = (smoothx-1) & 7
main.perform_scroll = smoothx==7
c64.SCROLX = (c64.SCROLX & %11111000) | smoothx
return false
}
}