如何将正交相机转换为透视和背面？

Question

我正在使用combinedcamera.js和orbitcontrols.js https://github.com/mrdoob/three.js/blob/master/examples/js/cameras/CombinedCamera.js https://github.com/mrdoob/three.js/blob/master/examples/js/controls/OrbitControls.js

我让它工作，以便可以切换摄像机，并且两者都可以放大和缩小。然而，轨道控制重新定位透视相机以模拟变焦，并且它不使用正交相机（它改变fov等）。

这最终导致相机远截头平面在透视模式下移动（我想要这个），并且它不会在正交模式下移动（我希望它移动）。

我通过使透视和正交相机得到重新定位来解决这个问题。正交相机不使用其位置来确定变焦，因此存在问题。

问题是当我在相机之间切换时，它们似乎没有相同的缩放量。

我想问题是，如何使正交相机依靠相机位置来确定变焦量，以便它总是看起来像透视相机一样具有相似的变焦效果？

Answer 1

好吧，经过大量的实验，我发现了一种能够获得足够接近结果的hackish方法。我意外地发现，如果将远视锥体值设置为25，它将完美地工作..所以我做了一个等式来补偿值是否不同。它足够接近，但也许有人可以看到它可以改进的地方？

我在combinedcamera.js中替换了

halfHeight /= this.zoom;
halfWidth /= this.zoom;

同

halfHeight /= ((this.cameraP.far/25)*this.zoom);
halfWidth /= ((this.cameraP.far/25)*this.zoom);

我在combinedcamera.js中添加了这一行

this.cameraO.far = this.cameraP.far+((this.cameraP.far/25)*this.zoom)-0.5;

就在此之前

this.cameraO.updateProjectionMatrix();

这是完整的部分

 THREE.CombinedCamera.prototype.toOrthographic = function () {

// Switches to the Orthographic camera estimating viewport from Perspective

var fov = this.fov;
var aspect = this.cameraP.aspect;
var near = this.cameraP.near;
var far = this.cameraP.far;

// The size that we set is the mid plane of the viewing frustum

var hyperfocus = ( near + far ) / 2;

var halfHeight = Math.tan( fov * Math.PI / 180 / 2 ) * hyperfocus;
var planeHeight = 2 * halfHeight;
var planeWidth = planeHeight * aspect;
var halfWidth = planeWidth / 2;

halfHeight /= ((this.cameraP.far/25)*this.zoom);
halfWidth /= ((this.cameraP.far/25)*this.zoom);

this.cameraO.left = -halfWidth;
this.cameraO.right = halfWidth;
this.cameraO.top = halfHeight;
this.cameraO.bottom = -halfHeight;

// this.cameraO.left = -farHalfWidth;
// this.cameraO.right = farHalfWidth;
// this.cameraO.top = farHalfHeight;
// this.cameraO.bottom = -farHalfHeight;

// this.cameraO.left = this.left / this.zoom;
// this.cameraO.right = this.right / this.zoom;
// this.cameraO.top = this.top / this.zoom;
// this.cameraO.bottom = this.bottom / this.zoom;

this.cameraO.far = this.cameraP.far+((this.cameraP.far/25)*this.zoom)-0.5;
this.cameraO.updateProjectionMatrix();

this.near = this.cameraO.near;
this.far = this.cameraO.far;
this.projectionMatrix = this.cameraO.projectionMatrix;

this.inPerspectiveMode = false;
this.inOrthographicMode = true;

 };

我也将this.zoom更改为1，用于透视相机

 THREE.CombinedCamera.prototype.toPerspective = function () {

// Switches to the Perspective Camera

this.near = this.cameraP.near;
this.far = this.cameraP.far;

this.cameraP.fov =  this.fov / 1 ;

this.cameraP.updateProjectionMatrix();

this.projectionMatrix = this.cameraP.projectionMatrix;

this.inPerspectiveMode = true;
this.inOrthographicMode = false;

 };

此外，我不得不调整轨道控制

this.dollyIn = function ( dollyScale ) {

    if ( dollyScale === undefined ) {

        dollyScale = getZoomScale();

    }

        scale /= dollyScale;
        scope.object.zoom = Math.max( this.minZoom, Math.min( this.maxZoom, this.object.zoom * dollyScale ) );
};

this.dollyOut = function ( dollyScale ) {

    if ( dollyScale === undefined ) {

        dollyScale = getZoomScale();

    }

        scale *= dollyScale;
        scope.object.zoom = Math.max( this.minZoom, Math.min( this.maxZoom, this.object.zoom / dollyScale ) );
};