小程序二次貝塞爾曲線實(shí)現(xiàn)購(gòu)物車(chē)商品曲線飛入效果

bezier: function (points, times) {
 
 // 0、以3個(gè)控制點(diǎn)為例，點(diǎn)A,B,C,AB上設(shè)置點(diǎn)D,BC上設(shè)置點(diǎn)E,DE連線上設(shè)置點(diǎn)F,則最終的貝塞爾曲線是點(diǎn)F的坐標(biāo)軌跡。
 
 // 1、計(jì)算相鄰控制點(diǎn)間距。
 
 // 2、根據(jù)完成時(shí)間,計(jì)算每次執(zhí)行時(shí)D在AB方向上移動(dòng)的距離，E在BC方向上移動(dòng)的距離。
 
 // 3、時(shí)間每遞增100ms，則D,E在指定方向上發(fā)生位移, F在DE上的位移則可通過(guò)AD/AB = DF/DE得出。
 
 // 4、根據(jù)DE的正余弦值和DE的值計(jì)算出F的坐標(biāo)。
 
 // 鄰控制AB點(diǎn)間距
 
 var bezier_points = [];
 
 var points_D = [];
 
 var points_E = [];
 
 const DIST_AB = Math.sqrt(Math.pow(points[1]['x'] - points[0]['x'], 2) + Math.pow(points[1]['y'] - points[0]['y'], 2));
 
 // 鄰控制BC點(diǎn)間距
 
 const DIST_BC = Math.sqrt(Math.pow(points[2]['x'] - points[1]['x'], 2) + Math.pow(points[2]['y'] - points[1]['y'], 2));
 
 // D每次在AB方向上移動(dòng)的距離
 
 const EACH_MOVE_AD = DIST_AB / times;
 
 // E每次在BC方向上移動(dòng)的距離 
 
 const EACH_MOVE_BE = DIST_BC / times;
 
 // 點(diǎn)AB的正切
 
 const TAN_AB = (points[1]['y'] - points[0]['y']) / (points[1]['x'] - points[0]['x']);
 
 // 點(diǎn)BC的正切
 
 const TAN_BC = (points[2]['y'] - points[1]['y']) / (points[2]['x'] - points[1]['x']);
 
 // 點(diǎn)AB的弧度值
 
 const RADIUS_AB = Math.atan(TAN_AB);
 
 // 點(diǎn)BC的弧度值
 
 const RADIUS_BC = Math.atan(TAN_BC);
 
 // 每次執(zhí)行
 
 for (var i = 1; i <= times; i++) {
 
 // AD的距離
 
 var dist_AD = EACH_MOVE_AD * i;
 
 // BE的距離
 
 var dist_BE = EACH_MOVE_BE * i;
 
 // D點(diǎn)的坐標(biāo)
 
 var point_D = {};
 
 point_D['x'] = dist_AD * Math.cos(RADIUS_AB) + points[0]['x'];
 
 point_D['y'] = dist_AD * Math.sin(RADIUS_AB) + points[0]['y'];
 
 points_D.push(point_D);
 
 // E點(diǎn)的坐標(biāo)
 
 var point_E = {};
 
 point_E['x'] = dist_BE * Math.cos(RADIUS_BC) + points[1]['x'];
 
 point_E['y'] = dist_BE * Math.sin(RADIUS_BC) + points[1]['y'];
 
 points_E.push(point_E);
 
 // 此時(shí)線段DE的正切值
 
 var tan_DE = (point_E['y'] - point_D['y']) / (point_E['x'] - point_D['x']);
 
 // tan_DE的弧度值
 
 var radius_DE = Math.atan(tan_DE);
 
 // 地市DE的間距
 
 var dist_DE = Math.sqrt(Math.pow((point_E['x'] - point_D['x']), 2) + Math.pow((point_E['y'] - point_D['y']), 2));
 
 // 此時(shí)DF的距離
 
 var dist_DF = (dist_AD / DIST_AB) * dist_DE;
 
 // 此時(shí)DF點(diǎn)的坐標(biāo)
 
 var point_F = {};
 
 point_F['x'] = dist_DF * Math.cos(radius_DE) + point_D['x'];
 
 point_F['y'] = dist_DF * Math.sin(radius_DE) + point_D['y'];
 
 bezier_points.push(point_F);
 
 }
 
 return {
 
 'bezier_points': bezier_points
 
 };
 
 }