创建动画

              // 创建一个关键帧动画
              let frameRate = 10
              // 动画名称 绑定的动画属性 帧率数 
              let animationRotate = new BABYLON.Animation(
                  "cameraRotation",
                  "alpha",
                  frameRate,
                  BABYLON.Animation.ANIMATIONTYPE_VECTOR3,
                  BABYLON.Animation.ANIMATIONLOOPMODE_CYCLE
              );
        
              let start_alpha = camera1.alpha
              // 定义动画的关键帧
              var keysRotation = [
                  {
                      frame: 0,
                      value: start_alpha
                  },
                  {
                      frame: frameRate,
                      value: start_alpha+camera_rotation_Speed
                  }
              ];
              // 将关键帧添加到动画中
              animationRotate.setKeys(keysRotation);
              // 将动画应用到相机的 rotation 属性上
              camera1.animations.push(animationRotate);
              const easingFunction = new BABYLON.SineEase();
              easingFunction.setEasingMode(BABYLON.EasingFunction.EASINGMODE_EASEINOUT);
              animationRotate.setEasingFunction(easingFunction);
              // 启动动画
              scene.beginAnimation(camera1, 0, frameRate, false);