htmlewislulu-html-ppt-skill/assets/animations/fx/galaxy-swirl.js

34 lines
1.0 KiB
JavaScript

(function(){
window.HPX = window.HPX || {};
window.HPX['galaxy-swirl'] = function(el){
const U = window.HPX._u;
const k = U.canvas(el), ctx = k.ctx;
const pal = U.palette(el);
const N = 800;
const parts = Array.from({length:N}, (_,i) => {
const arm = i%3;
const t = Math.random();
const r = t*180 + 8;
const base = (arm/3)*Math.PI*2;
return { r, a: base + Math.log(r+1)*1.6 + U.rand(-0.2,0.2),
c: pal[arm%pal.length],
s: U.rand(0.8, 2.2) };
});
const stop = U.loop((t) => {
ctx.fillStyle = 'rgba(0,0,0,0.15)';
ctx.fillRect(0,0,k.w,k.h);
const cx=k.w/2, cy=k.h/2;
for (const p of parts){
const a = p.a + t*0.15;
const x = cx + Math.cos(a)*p.r;
const y = cy + Math.sin(a)*p.r*0.7;
ctx.fillStyle = p.c;
ctx.globalAlpha = 0.7;
ctx.beginPath(); ctx.arc(x,y,p.s,0,Math.PI*2); ctx.fill();
}
ctx.globalAlpha = 1;
});
return { stop(){ stop(); k.destroy(); } };
};
})();