Particle fountain: Difference between revisions

{{draft task}}

Emulate a fountain of water droplets in a gravitational field bringbeing sprayed up and then falling back down.

The particle fountain should be generally ordered but individually chaotic; the particles should beingbe going mostly in the same direction, but should have slightly different vectors.

<langsyntaxhighlight lang="perl">#!/usr/bin/perl

}</langsyntaxhighlight>

<syntaxhighlight lang="raku" perl6line>use NativeCall;

"Raku Particle System!",

SDL_WINDOWPOS_CENTERED_MASK, SDL_WINDOWPOS_CENTERED_MASK,

$w, $h,

RESIZABLE

my int $xidx = 0;

my int $yidx = 1;

my int $pointidx = 0;

loop (my int $idx = 0; $idx < $particlenum; $idx = $idx + 1) {

my int $willdraw = 0;

if (@lifetimes[$idx] <= 0e0) {

if (rand < df) {

@lifetimes[$idx] = 25e-1; # time to live

@positions[$xidx] = ($w / 20e0).Num; # starting position x

@positions[$yidx] = ($h / 10).Num; # and y

@velocities[$xidx] = ($spread * rand - $spread/2 + reciprocate()) * 10; # starting velocity x

@velocities[$yidx] = (rand - 2.9e0) * $h / 20.5; # and y (randomized slightly so points reach different heights)

$willdraw = 1;

}

} else {

if @positions[$yidx] > $h / 10 && @velocities[$yidx] > 0 {

@velocities[$yidx] = @velocities[$yidx] * -0.3e0; # "bounce"

}

@velocities[$yidx] = @velocities[$yidx] + $h/10.Num * df; # adjust velocity

@positions[$xidx] = @positions[$xidx] + @velocities[$xidx] * df; # adjust position x

@positions[$yidx] = @positions[$yidx] + @velocities[$yidx] * df; # and y

@lifetimes[$idx] = @lifetimes[$idx] - df;

$willdraw = 1;

}

if ($willdraw) {

$points[$pointidx++] = (@positions[$xidx] * 10).floor; # gather all of the points that

$points[$pointidx++] = (@positions[$yidx] * 10).floor; # are still going to be rendered

}

$xidx = $xidx + 2;

$yidx = $xidx + 1;

}

$numpoints = ($pointidx - 1) div 2;

SDL_SetRenderDrawColor($renderer, 0x0, 0x0, 0x0, 0xff);

SDL_RenderClear($renderer);

SDL_SetRenderDrawColor($renderer, |hsv2rgb(((now % 5) / 5).round(.01), $saturation, 1), 0x7f);

SDL_RenderDrawPoints($renderer, $points, $numpoints);

SDL_RenderPresent($renderer);

K_UP => 82,

K_DOWN => 81,

K_LEFT => 80,

K_RIGHT => 79,

K_SPACE => 44,

K_PGUP => 75,

K_PGDN => 78,

K_Q => 20,

my $start = now;

while SDL_PollEvent($event) {

my $casted_event = SDL_CastEvent($event);

given $casted_event {

when *.type == QUIT {

last main;

}

when *.type == WINDOWEVENT {

if .event == RESIZED {

$w = .data1;

$h = .data2;

}

}

when *.type == KEYDOWN {

if KEY_CODES(.scancode) -> $comm {

given $comm {

when 'K_UP' { $saturation = (($saturation + .1) min 1e0) }

when 'K_DOWN' { $saturation = (($saturation - .1) max 0e0) }

when 'K_PGUP' { $spread = (($spread + .1) min 5e0) }

when 'K_PGDN' { $spread = (($spread - .1) max 2e-1) }

when 'K_RIGHT' { $range = (($range + .1) min 2e0) }

when 'K_LEFT' { $range = (($range - .1) max 1e-1) }

when 'K_SPACE' { &reciprocate = reciprocate() == 0 ?? sub { $range * sin(now) } !! sub { 0 } }

when 'K_Q' { last main }

}

}

}

}

}

update($df);

render();

$df = (now - $start).Num;

print fps();

state $fps-frames = 0;

state $fps-now = now;

state $fps = '';

$fps-frames++;

if now - $fps-now >= 1 {

$fps = [~] "\r", ' ' x 20, "\r",

sprintf "FPS: %5.1f ", ($fps-frames / (now - $fps-now));

$fps-frames = 0;

$fps-now = now;

}

$fps

state %cache;

%cache{"$h|$s|$v"} //= do {

my $c = $v * $s;

my $x = $c * (1 - abs( (($h*6) % 2) - 1 ) );

my $m = $v - $c;

[(do given $h {

when 0..^1/6 { $c, $x, 0 }

when 1/6..^1/3 { $x, $c, 0 }

when 1/3..^1/2 { 0, $c, $x }

when 1/2..^2/3 { 0, $x, $c }

when 2/3..^5/6 { $x, 0, $c }

when 5/6..1 { $c, 0, $x }

} ).map: ((*+$m) * 255).Int]

}