fix(core): determine isGPUDepth from session mode instead of texture existence

Summary:
The depth occlusion system determined isGPUDepth by checking whether an
ExternalTexture (nativeTexture) existed. This caused the preprocessing
shader and material shader to disagree on which depth formula to use,
because ExternalTexture availability can differ between render contexts.

- Derive isGPUDepth from session.depthUsage === 'gpu-optimized' so both
  the preprocessing and material shaders always use the same formula
- Extract shared isGPUDepth getter and getDepthTextureArray helper to
  eliminate duplicated texture selection logic
- Remove minMaxEntityCount reset from cleanup() since entities persist
  across XR sessions and don't re-qualify on session re-entry. This fixed the
  bug of MinMax occluded objects being hidden after reentering the session

Reviewed By: cabanier

Differential Revision: D102858221

fbshipit-source-id: e5c6265972f724fc8e32437936bd48606626b3fa

Author: zjm-meta

packages/core/src/depth/depth-sensing-system.ts

@@ -326,7 +326,6 @@ export class DepthSensingSystem extends createSystem(
     this.gpuDepthData = [];
     this.preprocessingPass?.dispose();
     this.preprocessingPass = undefined;
-    this.minMaxEntityCount = 0;
   }
 
   private updateEnabledFeatures(xrSession: XRSession | null): void {
@@ -365,21 +364,28 @@ export class DepthSensingSystem extends createSystem(
    * Renders a fullscreen pass per eye that computes min/max/avg depth in a 4×4
    * neighborhood, outputting to per-view 2D render targets.
    */
+  private get isGPUDepth(): boolean {
+    const session = this.xrManager.getSession();
+    return session?.depthUsage === 'gpu-optimized';
+  }
+
+  private getDepthTextureArray(): Texture | undefined {
+    return this.isGPUDepth
+      ? this.depthTextures?.getNativeTexture()
+      : this.depthTextures?.getDataArrayTexture();
+  }
+
   private runMinMaxPreprocessing(): void {
     if (this.minMaxEntityCount === 0) {
       return;
     }
 
-    const nativeTexture = this.depthTextures?.getNativeTexture();
-    const dataArrayTexture = this.depthTextures?.getDataArrayTexture();
-    const isGPUDepth = nativeTexture !== undefined;
-    const depthTextureArray = isGPUDepth
-      ? (nativeTexture as Texture)
-      : (dataArrayTexture as Texture);
+    const depthTextureArray = this.getDepthTextureArray();
     if (!depthTextureArray) {
       return;
     }
 
+    const isGPUDepth = this.isGPUDepth;
     const depthNear =
       (this.gpuDepthData[0] as unknown as { depthNear: number } | undefined)
         ?.depthNear ?? 0;
@@ -481,19 +487,16 @@ export class DepthSensingSystem extends createSystem(
    * VIEW_ID to select the correct stereo layer.
    */
   private updateOcclusionUniforms(): void {
-    const nativeTexture = this.depthTextures?.getNativeTexture();
-    const dataArrayTexture = this.depthTextures?.getDataArrayTexture();
-    const isGPUDepth = nativeTexture !== undefined;
-    const depthNear =
-      (this.gpuDepthData[0] as unknown as { depthNear: number } | undefined)
-        ?.depthNear ?? 0;
-
-    // Select the texture array: ExternalTexture for GPU, DataArrayTexture for CPU
-    const depthTextureArray = isGPUDepth ? nativeTexture : dataArrayTexture;
+    const depthTextureArray = this.getDepthTextureArray();
     if (!depthTextureArray) {
       return;
     }
 
+    const isGPUDepth = this.isGPUDepth;
+    const depthNear =
+      (this.gpuDepthData[0] as unknown as { depthNear: number } | undefined)
+        ?.depthNear ?? 0;
+
     this.renderer.getDrawingBufferSize(this.viewportSize);
 
     for (const [entity, entityUniforms] of this.entityShaderMap) {