feat(sdk): 新增focusObjectByDistance工具方法

packages/sdk/lib/utils/scene/controls.ts

@@ -1,12 +1,49 @@
-import {Object3D,Box3,Vector3} from "three";
+import {Object3D,Box3,Sphere,Vector3} from "three";
 import CameraControls from "camera-controls";
 
-export function focusObject(object:Object3D,controls:CameraControls,enableTransition: boolean = true){
+function getObjectBox3(object:Object3D){
     const box3 = new Box3();
     box3.setFromObject(object);
 
     if(box3.isEmpty()){
         box3.set(new Vector3(object.position.x-1, object.position.y-1, object.position.z-1), new Vector3(object.position.x+1, object.position.y+1, object.position.z+1));
     }
+
+    return box3;
+}
+
+export function focusObject(object:Object3D,controls:CameraControls,enableTransition: boolean = true){
+    const box3 = getObjectBox3(object);
+
     return controls.fitToBox(box3,enableTransition);
 }
+
+export function focusObjectByDistance(object:Object3D,controls:CameraControls,distance:number,enableTransition: boolean = true){
+    const box3 = getObjectBox3(object);
+    const sphere = box3.getBoundingSphere(new Sphere());
+
+    const center = sphere.center.clone();
+    const radius = Number.isFinite(sphere.radius) ? sphere.radius : 1;
+    const toSurfaceDistance = Math.max(distance, 0);
+    const toCenterDistance = Math.max(radius + toSurfaceDistance, 0.01);
+
+    const currentPosition = controls.getPosition(new Vector3());
+    const currentTarget = controls.getTarget(new Vector3());
+    const direction = currentPosition.sub(currentTarget);
+    if(direction.lengthSq() < 1e-6){
+        direction.set(0, 0, 1);
+    }
+    direction.normalize();
+
+    const nextPosition = center.clone().addScaledVector(direction, toCenterDistance);
+
+    return controls.setLookAt(
+        nextPosition.x,
+        nextPosition.y,
+        nextPosition.z,
+        center.x,
+        center.y,
+        center.z,
+        enableTransition
+    );
+}