prog8/examples/cx16/spotlight.p8

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%import math
%import textio
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%import palette
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; use the mouse to move the cursor around the screen
; it uses the fast direction routine to spotlight your mouse position.
; you can use the atan2() routine as well for more precision laser beams,
; but it will use a lot more memory due to the required lookup tables.
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main {
sub start() {
const uword WIDTH=320
const ubyte HEIGHT=240
uword xx
ubyte yy
void cx16.screen_mode(128, false)
cx16.mouse_config2(1)
txt.print("move the mouse for the spotlight.")
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; prefill
for yy in 0 to HEIGHT-1 {
cx16.FB_cursor_position(0, yy)
for xx in 0 to WIDTH-1 {
cx16.FB_set_pixel(math.direction(128, HEIGHT/2, clampx(xx), yy) + 128)
}
}
ubyte previous_direction
ubyte new_direction
; dim the screen
for new_direction in 128 to 128+23
palette.set_color(new_direction, $024)
; spotlight
repeat {
void cx16.mouse_pos()
new_direction = math.direction(128, HEIGHT/2, clampx(cx16.r0), cx16.r1L)
if new_direction != previous_direction {
sys.waitvsync()
palette.set_color(new_direction+128, math.rndw())
palette.set_color(previous_direction+128, $024)
previous_direction = new_direction
}
}
}
sub clampx(uword screenx) -> ubyte {
;; return clamp(screenx, 32, 255+32)-32 as ubyte
if screenx<32
return 0
else if screenx>255+32
return 255
return lsb(screenx-32)
}
}