ThreeJS。如何实现Zoomall并确保给定的框填充画布区域？ [英] ThreeJS. How to implement ZoomALL and make sure a given box fills the canvas area?

问题描述

我正在寻找一个函数，以确保给定的框或球体将在WebGL画布中可见，并且它将适合画布区域。
我使用透视摄像机，摄像机已经指向对象的中间。
我理解这可以通过改变FOV角度或通过沿着视图轴移动相机来实现。

I am looking for a function to ensure that a given box or sphere will be visible in a WebGL canvas, and that it will fit the canvas area. I am using a perspective camera and the camera already points to the middle of the object. I understand that this could be achieved by changing the FOV angle or by moving the camera along the view axis.

任何想法如何使用ThreeJS可以实现这一点。

Any idea how this could be achieved with ThreeJS ?

推荐答案

这是我最终实现它：

var camera = new THREE.PerspectiveCamera(35,1,1, 100000);
var controls = new THREE.TrackballControls( me.camera , container);
[...]


/**
 * point the current camera to the center
 * of the graphical object (zoom factor is not affected)
 *
 * the camera is moved in its  x,z plane so that the orientation 
 * is not affected either
 */
function pointCameraTo (node) {

    var me = this;

    // Refocus camera to the center of the new object
    var COG = shapeCenterOfGravity(node);

    var v = new THREE.Vector3();
    v.subVectors(COG,me.controls.target);

    camera.position.addVectors(camera.position,v);

    // retrieve camera orientation and pass it to trackball  
    camera.lookAt(COG);
    controls.target.set( COG.x,COG.y,COG.z );  

};

/**
 *  Zoom to object
 */
function zoomObject (node) {

   var me = this; 

   var bbox = boundingBox(node);
   if (bbox.empty()) {
       return;
   }
   var COG =  bbox.center();

   pointCameraTo(node);

   var sphereSize = bbox.size().length() * 0.5;
   var distToCenter = sphereSize/Math.sin( Math.PI / 180.0 * me.camera.fov * 0.5);

   // move the camera backward 

   var target = controls.target;
   var vec = new THREE.Vector3();
   vec.subVectors( camera.position, target );
   vec.setLength( distToCenter );
   camera.position.addVectors(  vec , target );
   camera.updateProjectionMatrix();
   render3D();
};

这样的例子可以在 https://github.com/erossignon/node-occ/blob/master/sample/client/GeomView.js

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