javascript - Three.js raycaster 相交

Question

我编写了下面的代码来获取与 3d 形状的交点。它运作良好，但如果有两个与形状的交点，它只返回最远的交点，而我需要与形状最近的交点。我怎样才能到达最近的十字路口？

  /*here I create a cube*/

            var geometry0 = new THREE.Geometry()
            geometry0.vertices = [new THREE.Vector3(0.5, -0.5, 0.5), new THREE.Vector3(-0.5, -0.5, 0.5), new THREE.Vector3(-0.5, -0.5, -0.5), new THREE.Vector3(0.5, -0.5, -0.5), new THREE.Vector3(0.5, 0.5, 0.5), new THREE.Vector3(-0.5, 0.5, 0.5), new THREE.Vector3(-0.5, 0.5, -0.5), new THREE.Vector3(0.5, 0.5, -0.5)];
            geometry0.faces = [new THREE.Face3(3, 2, 1), new THREE.Face3(3, 1, 0), new THREE.Face3(4, 5, 6), new THREE.Face3(4, 6, 7), new THREE.Face3(0, 1, 5), new THREE.Face3(0, 5, 4), new THREE.Face3(1, 2, 6), new THREE.Face3(1, 6, 5), new THREE.Face3(2, 3, 7), new THREE.Face3(2, 7, 6), new THREE.Face3(3, 0, 4), new THREE.Face3(3, 4, 7)];
            geometry0.computeFaceNormals();
            geometry0.computeVertexNormals();
            var material0 = new THREE.MeshBasicMaterial({color: 0x39d2dbe7fff39d2, transparent: true, opacity: 0});
            mesh0 = new THREE.Mesh(geometry0, material0);
            egh0 = new THREE.EdgesHelper(mesh0, 0x000);
            egh0.material.linewidth = 2;
            scene.add(egh0);


            objects.push(mesh0);
            projector = new THREE.Projector();
            console.log(objects);
            mouse2D = new THREE.Vector3(0, 10000, 0.5);//controllare i valori



    /* here I create the ray */


document.addEventListener('click', onDocumentMouseClick, false);


        function onDocumentMouseClick(event) {

            event.preventDefault();

            mouse2D.x = (event.clientX / window.innerWidth) * 2 - 1;
            mouse2D.y = -(event.clientY / window.innerHeight) * 2 + 1;
             var vector = new THREE.Vector3( mouse2D.x, mouse2D.y, 0.5 );

            projector.unprojectVector( vector, camera );

            var raycaster = new THREE.Raycaster( camera.position, vector.sub( camera.position ).normalize() );


            var intersects = raycaster.intersectObjects( objects );

            if (intersects.length > 0) {
                console.log("ok");} 

如果我检查 intersects[0].point 我只能看到相交的立方体的最远点面而不是第一个(例如，如果你看着你面前的立方体并发出一条射线，这条射线在相交之前第一个面和后一个面与第一个面后面的第二个面相交。) 此代码的目标是仅在您单击顶点时创建一个事件。 所以在这之后我写了代码来计算点击点和所有顶点的欧氏距离 并返回离点击点最近的顶点。 如果您有其他想法，欢迎仅在单击顶点时触发事件。

Answer 1

是的，射线转换 的基本思想是我们转换一条垂直于平面的射线，然后找出射线相交的对象列表。

因此，要访问第一个元素，您只需添加以下代码即可。

var intersects = raycaster.intersectObjects(objects);

if (intersects.length > 0) {
       var firstIntersectedObject  = intersects[0];
       // this will give you the first intersected Object if there are multiple.
    }

这里是 one of my other SO post我在其中以更详细的方式解释了一些事情，您可以引用它以更好地理解光线转换的功能。