GIS技术支持工程师日常工作随笔-罗盘操作模拟

本文纯属个人见解，可能是正经的胡扯。

最近在支持工作中有部分客户提出能否模拟导航罗盘的操作，包括俯仰和旋转等。在看不到源码的情况下，小编我只能通过操作现象来推测。在旋转时，首先看到的是相机似乎是绕轴的旋转，在俯仰时，相机似乎又是绕点固定半径操作。以上的一些迹象表明，相机应该是被锁死在一个点上。话不多说，下面来看代码：

function compassControlsimulation(scene) {
                this.scene = scene
                this.islocked = false

                compassControlsimulation.prototype.lookat = function() {
                    var that = this
                    var pixcelx = that.scene.canvas.width / 2
                    var pixcely = that.scene.canvas.height / 2
                    var position = that.scene.pickPosition(new Cesium.Cartesian2(pixcelx, pixcely))

                    var transform = Cesium.Transforms.eastNorthUpToFixedFrame(position);

                    that.scene.camera.lookAtTransform(transform)
                    that.islocked = true
                }
                compassControlsimulation.prototype.unlookat = function() {
                    var that = this
                    that.scene.camera.lookAtTransform(Cesium.Matrix4.IDENTITY)
                    that.islocked = false
                }
                compassControlsimulation.prototype.rotatedown = function(value) {
                    var that = this
                    if (typeof value === "number" && that.islocked === true) {
                        that.scene.camera.rotateDown(value)
                    }
                }
                compassControlsimulation.prototype.rotateup = function(value) {
                    var that = this
                    if (typeof value === "number" && that.islocked === true) {
                        that.scene.camera.rotateUp(value)
                    }
                }
                compassControlsimulation.prototype.rotateleft = function(value) {
                    var that = this
                    if (typeof value === "number" && that.islocked === true) {
                        that.scene.camera.rotateLeft(value)
                    }
                }
                compassControlsimulation.prototype.rotateright = function(value) {
                    var that = this
                    if (typeof value === "number" && that.islocked === true) {
                        that.scene.camera.rotateRight(value)
                    }
                }
            }