javascript多边形碰撞检测

javascript多边形碰撞检测

原理就是 循环每个顶点判断是不是在多边形内

         const app = new PIXI.Application({ antialias: true });
document.body.appendChild(app.view);

const graphics = new PIXI.Graphics();


// draw polygon
const path = [600, 370, 700, 460, 780, 420, 730, 570, 590, 520];

graphics.lineStyle(0);
graphics.beginFill(0x3500FA, 1);
graphics.drawPolygon(path);
graphics.endFill();

app.stage.addChild(graphics);

  var xuanzhuan = PIXI.Sprite.from('/moban/images/share.jpg');
  xuanzhuan.width=120;
  xuanzhuan.height=120;
  xuanzhuan.x=13;
  xuanzhuan.y=33;
   app.stage.addChild(xuanzhuan);


    xuanzhuan.interactive = true;

    xuanzhuan.buttonMode = true;
      xuanzhuan
        .on('pointerdown', onDragStart)
        .on('pointerup', onDragEnd)
        .on('pointerupoutside', onDragEnd)
        .on('pointermove', onDragMove);

   function onDragStart(event) {
    // store a reference to the data
    // the reason for this is because of multitouch
    // we want to track the movement of this particular touch
    this.data = event.data;
    this.alpha = 0.5;
    this.dragging = true;
}

function onDragEnd() {
    this.alpha = 1;
    this.dragging = false;
    // set the interaction data to null
    this.data = null;
}
     var   posPolygon=[];
         var dianlist={};
        dianlist['x']=600;
        dianlist['y']=370; 
        posPolygon.push(dianlist)
    var dianlist={};
        dianlist['x']=700;
        dianlist['y']=460; 
        posPolygon.push(dianlist)    
    var dianlist={};
        dianlist['x']=780;
        dianlist['y']=420; 
        posPolygon.push(dianlist)      
    var dianlist={};
        dianlist['x']=730;
        dianlist['y']=570; 
      posPolygon.push(dianlist)  
    var dianlist={};
        dianlist['x']=590;
        dianlist['y']=520; 
        posPolygon.push(dianlist)
function onDragMove() {
    if (this.dragging) {
        const newPosition = this.data.getLocalPosition(this.parent);
        this.x = newPosition.x;
        this.y = newPosition.y;

        var baoweihe=this.getBounds();
        var youxiajiaox=baoweihe.x+baoweihe.width;
        var youxiajiaoy=baoweihe.y+baoweihe.height;

        var poslist=[];
          var pos={};
        pos['x']=baoweihe.x;
        pos['y']=baoweihe.y;       
        poslist.push(pos);           

   var pos={};
        pos['x']=youxiajiaox;
        pos['y']=baoweihe.y;       
        poslist.push(pos);           
        var pos={};
        pos['x']=youxiajiaox;
        pos['y']=youxiajiaoy;       
        poslist.push(pos);

        var pos={};
        pos['x']=baoweihe.x;
        pos['y']=youxiajiaoy;       
        poslist.push(pos);        

          
    
        var ispengzhuang=PolygonInPolygon(poslist, posPolygon,5);
        if(ispengzhuang){
            alert('碰撞了');
        }


    }
}

function PolygonInPolygon(posPolygonA, posPolygonB, count){
    console.log(posPolygonA);
       var count1=posPolygonA.length;
      for(var i=0;i<count1;i++ ){
        var pos=posPolygonA[i];
           console.log(pos);
          var  ispengzhuang=PointInPolygon( pos, posPolygonB, count);
          if(ispengzhuang){
            alert('碰撞了')
          }
      }
}

function PointInPolygon( pos, posPolygonB, count)
{
    var cross = 0; //交点个数
       
    for( var i = 0; i < count; i++ )
    {
        var p1 = posPolygon[i];
        var p2 = posPolygon[(i + 1) % count]; //下一个节点
 
        // p1p2这条边与水平线平行
        if( p1.y == p2.y )
            continue;
 
        // 交点在p1p2的延长线上
        if( pos.y < Math.min( p1.y, p2.y ) )
            continue;
 
        // 交点在p1p2的延长线上
        if( pos.y > Math.max( p1.y, p2.y ) )
            continue;
            
        // 计算交点 X 左边 ： (p2.y - p1.y)/(p2.x - p1.x) = (y - p1.y)/(x - p1.x)
        // 直线 K 值相等， 交点y = pos.y
        let x = (pos.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y) + p1.x
        // 只统计单边交点，即点的正向方向
        if(x > pos.x)
            cross ++;
    }
 
    return cross % 2 == 1;
}