CSS3 实现穿梭星空动画

 * { background:black; padding:0; margin:0; } canvas { padding:0; margin:0; width:100%; height:100%; }

 function $i(t) { return document.getElementById(t) } function $r(t, r) { document.getElementById(t).removeChild(document.getElementById(r)) } function $t(t) { return document.getElementsByTagName(t) } function $c(t) { return String.fromCharCode(t) } function $h(t) { return ("0" + Math.max(0, Math.min(255, Math.round(t))).toString(16)).slice(-2) } function _i(t, r) { $t("div")[t].innerHTML += r } function _h(t) { return hires ? Math.round(t / 2) : t } function get_screen_size() { var t = document.documentElement.clientWidth, r = document.documentElement.clientHeight; return Array(t, r) } function init() { for (var t = 0; n > t; t++) star[t] = new Array(5), star[t][0] = Math.random() * w * 2 - 2 * x, star[t][1] = Math.random() * h * 2 - 2 * y, star[t][2] = Math.round(Math.random() * z), star[t][3] = 0, star[t][4] = 0; var r = $i("starfield"); r.style.position = "absolute", r.width = w, r.height = h, context = r.getContext("2d"), context.fillStyle = "rgb(0,0,0)", context.strokeStyle = "rgb(255,255,255)" } function anim() { mouse_x = cursor_x - x, mouse_y = cursor_y - y, context.fillRect(0, 0, w, h); for (var t = 0; n > t; t++) test = !0, star_x_save = star[t][3], star_y_save = star[t][4], star[t][0] += mouse_x >> 4, star[t][0] > x << 1 && (star[t][0] -= w << 1, test = !1), star[t][0] <-x << 1 && (star[t][0] += w << 1, test = !1), star[t][1] += mouse_y >> 4, star[t][1] > y << 1 && (star[t][1] -= h << 1, test = !1), star[t][1] <-y << 1 && (star[t][1] += h << 1, test = !1), star[t][2] -= star_speed, star[t][2] > z && (star[t][2] -= z, test = !1), star[t][2] <0 && (star[t][2] + test=!1), star[t][3]=x star[t][0]> 0 && w > star_x_save && star_y_save > 0 && h > star_y_save && test && (context.lineWidth = 2 * (1 - star_color_ratio * star[t][2]), context.beginPath(), context.moveTo(star_x_save, star_y_save), context.lineTo(star[t][3], star[t][4]), context.stroke(), context.closePath()); timeout = setTimeout("anim()", fps) } function start() { resize(), anim() } function resize() { w = parseInt(-1 != url.indexOf("w=") ? url.substring(url.indexOf("w=") + 2, -1 != url.substring(url.indexOf("w=") + 2, url.length).indexOf("&") ? url.indexOf("w=") + 2 + url.substring(url.indexOf("w=") + 2, url.length).indexOf("&") : url.length) : get_screen_size()[0]), h = parseInt(-1 != url.indexOf("h=") ? url.substring(url.indexOf("h=") + 2, -1 != url.substring(url.indexOf("h=") + 2, url.length).indexOf("&") ? url.indexOf("h=") + 2 + url.substring(url.indexOf("h=") + 2, url.length).indexOf("&") : url.length) : get_screen_size()[1]), x = Math.round(w / 2), y = Math.round(h / 2), z = (w + h) / 2, star_color_ratio = 1 / z, cursor_x = x, cursor_y = y, init() } var url = document.location.href, flag = !0, test = !0, n = parseInt(-1 != url.indexOf("n=") ? url.substring(url.indexOf("n=") + 2, -1 != url.substring(url.indexOf("n=") + 2, url.length).indexOf("&") ? url.indexOf("n=") + 2 + url.substring(url.indexOf("n=") + 2, url.length).indexOf("&") : url.length) : 812), w = 0, h = 0, x = 0, y = 0, z = 0, star_color_ratio = 0, star_x_save, star_y_save, star_ratio = 115, star_speed = 5, star_speed_save = 0, star = new Array(n), color, opacity = .1, cursor_x = 0, cursor_y = 0, mouse_x = 0, mouse_y = 0, canvas_x = 0, canvas_y = 0, canvas_w = 0, canvas_h = 0, context, key, ctrl, timeout, fps = 0; start();