雷没有准确地确定交叉点答案

【问题标题】：Ray does not accurately determine the intersection雷没有准确地确定交叉点
【发布时间】：2020-03-02 01:23:49
【问题描述】：

我想找到曲线和直线的交点。创建了光线投射，但效果不佳。射线的点离实际的交点很远。

Webgl 1，threejs 0.109

        var sartPoint = new THREE.Vector3( -30, -50, 0 );
        var endPoint = new THREE.Vector3( 50, 80, 0 );
        var geometry = new THREE.Geometry();
        geometry.vertices.push(sartPoint);
        geometry.vertices.push(endPoint);
        var materialTmp = new THREE.LineBasicMaterial( { color: 0xffffff, linewidth: 5 } );
        var itemTmp = new THREE.Line( geometry, materialTmp );
        _this.add( itemTmp, 'lines' );
        scene.updateMatrixWorld()

       var curve = new THREE.EllipseCurve(
          0,  0,            // ax, aY
          10, 10,           // xRadius, yRadius
          0,  2 * Math.PI,  // aStartAngle, aEndAngle
          false,            // aClockwise
          0                 // aRotation
        );

        var points = curve.getPoints( 10 );
        var geometry = new THREE.BufferGeometry().setFromPoints( points );
        var material = new THREE.LineBasicMaterial( { color : 0xff00ff } );
        var ellipse = new THREE.Line( geometry, material );
        scene.add( ellipse );

        var raycaster = new THREE.Raycaster(sartPoint, endPoint.clone().normalize());

        var intersects = raycaster.intersectObject( ellipse );
        console.log(intersects);
        if(intersects.length > 0){
          // FIRST dot of intersect
          var dotGeometry2 = new THREE.Geometry();
          dotGeometry2.vertices.push(intersects[0].point);
          var dotMaterial2 = new THREE.PointsMaterial( { size: 5, color: 0x00ff00 } );
          var dot2 = new THREE.Points( dotGeometry2, dotMaterial2 );
          _this.add( dot2, 'points' );
        }

【问题讨论】：

标签： three.js raycasting

【解决方案1】：

Raycaster 构造函数的第二个参数是一个方向向量。而不是：

endPoint.clone().normalize()

我想你想要：

endPoint.clone().sub(startPoint).normalize()

【讨论】：

【解决方案2】：

如果曲线.getPoints(10); 什么时候曲线.getPoints(100); 这行不通。

【讨论】：