用canvas画一颗花心
jopen
8年前
一、心形函数
function getHeartPoint(angle) {/*agnle=10*/ var t = angle / Math.PI; var x = 19.5 * (16 * Math.pow(Math.sin(t), 3))*chen; var y = - 20 * (13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t))*chen; return {x:offsetX + x, y:offsetY + y}; } 二、用贝叶斯曲线画出花朵
function Vector(x,y){ this.x=x; this.y=y; } Vector.prototype={ rotate:function(theta){ var x = this.x; var y = this.y; this.x = Math.cos(theta) * x - Math.sin(theta) * y; this.y = Math.sin(theta) * x + Math.cos(theta) * y; return this; }, mult:function(f){ this.x *= f; this.y *= f; return this; }, clone:function(){ return new Vector(this.x,this.y); } } function Petal(xadd,yadd,startAngle,angle,grow){ this.xadd=xadd; this.yadd=yadd; this.startAngle=startAngle; this.angle=angle; this.grow=grow; this.r=1; } Petal.prototype={ draw:function(){/*r控制里面空白的大小，angle控制花瓣的数量，startAngle控制起始花瓣的位置，mult方法用来计算出两个控制点的位置*/ var v1, v2, v3, v4; v1 = new Vector(0, this.r).rotate(this.startAngle * 2 * Math.PI /360); v2 = v1.clone().rotate(this.angle * 2 * Math.PI /360); v3 = v1.clone().mult(this.xadd); //.rotate(this.tanAngleA); v4 = v2.clone().mult(this.yadd); //.rotate(this.tanAngleB); ctx.strokeStyle = 'rgba('+getRandInt(128,255)+','+getRandInt(0,128)+','+getRandInt(0,128)+',0.1)'; ctx.beginPath(); ctx.lineWidth=1; ctx.moveTo(v1.x, v1.y); ctx.bezierCurveTo(v3.x, v3.y, v4.x, v4.y, v2.x, v2.y); ctx.stroke(); }, update:function(){ if(this.r<=10){ this.draw(); this.r+=this.grow; }else{ petals.splice(petals.indexOf(this),1); } } } /*页面加载时启动动画*/ window.onload=function(){ ctx.translate(200, 200); //ctx.globalCompositeOperation='lighter'; for(var i=0;i<count;i++){ var p=new Petal(getRandInt(3,8),getRandInt(3,8),startAngle,angle,getRand(0.3,0.5)); petals.push(p); startAngle+=angle; p.update(); } setInterval(function(){ for(var i=0;i<petals.length;i++){ petals[i].update(); } },100); } 三、把花朵绘到心形函数的路径上，最终代码
var cas=document.getElementById('cas'), ctx=cas.getContext('2d'); cas.width=600; cas.height=700, count=getRandInt(8,15), angle=360/count, petals=[], startAngle=getRandInt(0,90), chen=0.8, offsetX=300, offsetY=300, dots=[], timer1=0, timer2=0; window.onload=function(){ var vector={},i=10; timer1=setInterval(function(){ vector=getHeartPoint(i); dots.push(new Dot(vector.x,vector.y)); if(i<30){ i+=0.3 }else{ clearInterval(timer1); } },100); timer2=setInterval(function(){ for(var i=0;i<dots.length;i++){ dots[i].draw(); } }); } function Dot(x,y){ this.transX=x; this.transY=y; this.petals=[]; this.init(); } Dot.prototype={ init:function(){ for(var i=0;i<count;i++){ var color=getRGBA(255,128,128,0,128,0,0.1); var p=new Petal(getRandInt(1,5),getRandInt(1,5),startAngle,angle,getRand(0.1,0.5),color); this.petals.push(p); startAngle+=angle; //p.update(); } }, draw:function(){ ctx.save(); ctx.translate(this.transX, this.transY); for(var i=0;i<this.petals.length;i++){ this.petals[i].update(); } ctx.restore(); } } function rgbaStr(r, g, b, a) { return 'rgba(' + r + ',' + g + ',' + b + ',' + a + ')'; }; function getRGBA(rmin, rmax, gmin, gmax, bmin, bmax, a) { var r = Math.round(getRand(rmin, rmax)); var g = Math.round(getRand(gmin, gmax)); var b = Math.round(getRand(bmin, bmax)); var limit = 5; if (Math.abs(r - g) <= limit && Math.abs(g - b) <= limit && Math.abs(b - r) <= limit) { return rgbaStr(rmin, rmax, gmin, gmax, bmin, bmax, a); } else { return rgbaStr(r, g, b, a); } }; function getHeartPoint(angle) {/*agnle=10*/ var t = angle / Math.PI; var x = 19.5 * (16 * Math.pow(Math.sin(t), 3))*chen; var y = - 20 * (13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t))*chen; return {x:offsetX + x, y:offsetY + y}; } function Vector(x,y){ this.x=x; this.y=y; } Vector.prototype={ rotate:function(theta){ var x = this.x; var y = this.y; this.x = Math.cos(theta) * x - Math.sin(theta) * y; this.y = Math.sin(theta) * x + Math.cos(theta) * y; return this; }, mult:function(f){ this.x *= f; this.y *= f; return this; }, clone:function(){ return new Vector(this.x,this.y); } } function Petal(xadd,yadd,startAngle,angle,grow,color){ this.xadd=xadd; this.yadd=yadd; this.startAngle=startAngle; this.angle=angle; this.grow=grow; this.c=color; this.r=1; } Petal.prototype={ draw:function(){/*r控制里面空白的大小，angle控制花瓣的数量，startAngle控制起始花瓣的位置，mult方法用来计算出两个控制点的位置*/ var v1, v2, v3, v4; v1 = new Vector(0, this.r).rotate(this.startAngle * 2 * Math.PI /360); v2 = v1.clone().rotate(this.angle * 2 * Math.PI /360); v3 = v1.clone().mult(this.xadd); //.rotate(this.tanAngleA); v4 = v2.clone().mult(this.yadd); //.rotate(this.tanAngleB); ctx.beginPath(); ctx.strokeStyle = this.c; console.log(ctx.strokeStyle); ctx.lineWidth=1; ctx.moveTo(v1.x, v1.y); ctx.bezierCurveTo(v3.x, v3.y, v4.x, v4.y, v2.x, v2.y); ctx.stroke(); }, update:function(){ if(this.r<8){ this.draw(); this.r+=this.grow; }else{ petals.splice(petals.indexOf(this),1); } } } function getRandInt(min,max){ return Math.floor(Math.random()*(max-min)+min); } function getRand(min,max){ return Math.random()*(max-min)+min; }