几个图形学的小例子（canvas实现）

作者: Rememberautumn 分类: html5,JavaScript,Web前端 发布时间: 2016-04-26 20:18 阅读: 3,086

微信小程序转支付宝小程序命令行工具

wordpress转APP方案

mui + vue单文件组件开发， 热更新脚手架

画个钻石（其实可以通过坐标系的旋转来做，更简单，当时没想到）

eCode_canvas_index_ht

 

 

 

 

 

 

 

 

 

 

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var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
context.width = 600;
context.fillStyle = "#000";
context.beginPath();
context.translate(400,400);
var bj = 200;
var pi =3.1415;
var point=[];
for (var i = 0; i < 8; i++) {
point.push({
x:parseInt(Math.sin(pi*i/4)*200),
y:parseInt(Math.cos(pi*i/4)*200)
});
}
  for (var i = 0; i < 8; i++) {
   for (var j = i+1; j < 8; j++) {
   context.moveTo(point[i].x,point[i].y);
   context.lineTo(point[j].x,point[j].y);
   }
  }
  context.stroke()

图形学上机—一棵树

FireShot Pro Screen Capture #004 - '树' - _H__sublimeCode_canvas_tree_ht

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var canvas = document.getElementById('canvas');
var c = canvas.getContext('2d');
c.width=800;
c.height=800;
c.fillStyle = '#FFF';
c.beginPath();
// function tree(begin,length,w,i) {
// console.log(begin)
// length=parseInt(length*0.6);
// if (length<10) {
// return;
// }
// c.moveTo(begin.x,begin.y);
// if (w) {
// i++;
// x= parseInt(begin.x-length*Math.cos(3.14/6*i));
// y=parseInt(begin.y-length*Math.sin(3.14/6*i));
// console.log('x'+x+"y"+y);
// c.lineTo(x,y);
// tree({x:parseInt(begin.x-length*Math.cos(3.14/6*i)*0.4),y:parseInt(begin.y-length*Math.sin(3.14/6*i)*0.4)},length*0.68,1,i-3);
 
// tree({x:parseInt(begin.x-length*Math.cos(3.14/6*i)*0.4),y:parseInt(begin.y-length*Math.sin(3.14/6*i)*0.4)},length*0.68,0,i+1);
 
// }else{
// i+=1;
// x= parseInt(begin.x+length*Math.cos(3.14/6*i));
// y=parseInt(begin.y-length*Math.sin(3.14/6*i));
// console.log('x'+x+"y"+y);
// c.lineTo(x,y);
// // tree({x:parseInt(begin.x+length*Math.cos(3.14/6*i)*0.4),y:parseInt(begin.y-length*Math.sin(3.14/6*i)*0.4)},length*0.68,1,i+-11);
 
// // tree({x:parseInt(begin.x+length*Math.cos(3.14/6*i)*0.4),y:parseInt(begin.y-length*Math.sin(3.14/6*i)*0.4)},length*0.68,0,i-3);
// }
// }
// tree({x:400,y:500},600,1,0)
// tree({x:400,y:500},600,0,0)
function getxy(x,y,length,angle) {
var endx = parseInt(length*Math.cos(angle)+x);
var endy = parseInt(length*Math.sin(angle)+y);
return {x:endx,y:endy};
}
var trees =function (x,y,length,angle) {
this.x = x;
this.y = y;
this.endx = '';
this.endy = '';
this.length = length;
this.angle = angle;
this.point = [];
};
trees.prototype.getEnd = function() {
this.endx = this.length*Math.cos(this.angle)+this.x;
this.endy = this.length*Math.sin(this.angle)+this.y;
};
trees.prototype.getPoint = function () {
var add = this.length*0.318;
var rootlenth = 0;
var length = this.length*0.5;
for(var i=0;rootlenth+add*0.718+10<this.length;i++){
rootlenth +=add;
add*=0.718;
var point = getxy(this.x,this.y,rootlenth,this.angle);
console.log(point)
length = length*0.7
this.point.push({x:point.x,y:point.y,length:length,angle:(this.angle-Math.PI/3)});
this.point.push({x:point.x,y:point.y,length:length,angle:this.angle+Math.PI/3});
}
};
trees.prototype.init = function () {
this.getEnd();
this.getPoint();
};
 
function draw(x,y,length,angle) {
var tree = new trees(x,y,length,angle);
tree.init();
c.moveTo(x,y);
c.lineTo(tree.endx,tree.endy);
tree.point.forEach(function (point) {
draw(point.x,point.y,point.length,point.angle);
});
// console.log(tree);
}
draw(400,500,400,Math.PI*3/2);
c.stroke();

填充图形–（做法有点蠢）

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$=function (str) {
return document.querySelector(str);
}
var canvas = $('#canvas');
var c = canvas.getContext('2d');
var line = [{
begin:{
x:100,
y:100
},
end:{
x:100,
y:200
}
},{
begin:{
x:100,
y:200
},
end:{
x:150,
y:150
}
},{
begin:{
x:150,
y:150
},
end:{
x:200,
y:200
}
},
{
begin:{
x:200,
y:200
},
end:{
x:200,
y:100
}
},
{
begin:{
x:200,
y:100
},
end:{
x:100,
y:100
}
},
 
];
var draw = [];
for(var i=1;i<=600;i++){
draw[i] = [];
for (var j = 1; j <=600; j++) {
draw[i][j]=false;
}
}
line.forEach(function (line) {
var k = (line.begin.y-line.end.y)/(line.begin.x-line.end.x);
var add = line.begin.x>line.end.x?-1:1;
console.log(add+'s'+k)
var x = line.begin.x;
var y=line.begin.y;
while(x!=line.end.x){
y+=k;
draw[x][parseInt(y)] = !draw[x][parseInt(y)];
x+=add;
}
});
// console.log(draw)
c.beginPath();
for (var i = 1; i <=600; i++) {
var bool = false;
for (var j = 1; j <= 600; j++) {
if (draw[i][j]&&bool) {
bool = false;
c.lineTo(i,j);
}else if (draw[i][j]) {
bool = true;
c.moveTo(i,j);
}
}
}
c.stroke();

 

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