Handle URI with spaces in I3DM

CHANGES.md

@@ -1,4 +1,8 @@
 
+Version ?.?.? - 2023-mm-dd
+
+- When an I3DM refers to an external glTF asset with a URI, then the URI has to be padded with `0x20` (space) bytes if necessary to satisfy the alignment requirements. The validator only accepted `0x00` (zero) bytes as padding bytes. Now the validator properly handles trailing spaces, and reports the presence of zero-bytes with a validation warning ([#276](https://github.com/CesiumGS/3d-tiles-validator/issues/276))
+
 Version 0.4.1 - 2023-05-02
 
 - Moved most of the internal implementation into the `3d-tiles-tools`, and replaced it with a dependency to `3d-tiles-tools`

specs/TilesetValidationSpec.ts

@@ -951,4 +951,12 @@ describe("Tileset validation", function () {
     );
     expect(result.length).toEqual(0);
   });
+
+  it("detects no issues in tilesets/tiles/i3dm/i3dmWithUri/tileset.json", async function () {
+    const result = await Validators.validateTilesetFile(
+      "specs/data/tilesets/tiles/i3dm/i3dmWithUri/tileset.json"
+    );
+    expect(result.length).toEqual(1);
+    expect(result.get(0).type).toEqual("CONTENT_VALIDATION_WARNING");
+  });
 });

specs/data/tilesets/tiles/i3dm/i3dmWithUri/README.md

@@ -0,0 +1,17 @@
+
+
+A tileset that refers to a single I3DM file, which in turn refers to a 
+single glTF file (the `Box` glTF sample model).
+
+The I3DM refers to the GLB using a URI, in contrast to embedding the 
+GLB inside the GLB. 
+
+The URI is `"Box.glb    "`: It includes spaces, as a regression test 
+for https://github.com/CesiumGS/3d-tiles-validator/issues/276 .
+
+The string (including spaces) consists of 11 characters. 
+
+In order to achieve the alignment requirement, the payload data is 
+padded with _additional_ `0x00` bytes to achieve a payload length 
+of 16 bytes. This is not allowed by the specification, and should 
+cause a WARNING during the validation.

specs/data/tilesets/tiles/i3dm/i3dmWithUri/tileset.json

@@ -0,0 +1,19 @@
+{
+  "asset" : {
+    "version" : "1.1"
+  },
+  "geometricError" : 2.0,
+  "root" : {
+    "boundingVolume" : {
+      "box" : [ 
+        0.0, 0.0, 0.0, 
+        0.5, 0.0, 0.0, 
+        0.0, 0.5, 0.0, 
+        0.0, 0.0, 0.5 ]
+    },
+    "geometricError" : 1.0,
+    "content": {
+      "uri": "i3dmWithUri.i3dm"
+    }
+  }
+}

src/tileFormats/I3dmValidator.ts

@@ -265,9 +265,22 @@ export class I3dmValidator implements Validator<Buffer> {
         result = false;
       }
     } else {
-      // The GLB data was a URI. Create the URI from the buffer, and remove
-      // any zero-bytes from the string that may be introduced by padding
-      const glbUri = glbData.toString().replace(/\0/g, "");
+      // The GLB data was a URI, as indicated by `gltfFormat === 0`.
+      // The padding bytes in this case should be 0x20 (space) bytes,
+      // so issue a warning if the buffer contais 0x00 (zero) bytes.
+      if (glbData.includes("\0")) {
+        const message =
+          `The field containing the URI of the glTF asset contained ` +
+          `0x00 (zero)-bytes, but should only be padded with 0x20 (space) bytes`;
+        const issue = ContentValidationIssues.CONTENT_VALIDATION_WARNING(
+          uri,
+          message
+        );
+        context.addIssue(issue);
+      }
+      // Create the URI from the buffer, and remove any bytes (zeros
+      // or trailing) that may be introduced by padding.
+      const glbUri = glbData.toString().replace(/\0/g, "").trim();
       const resourceResolver = context.getResourceResolver();
       const resolvedGlbData = await resourceResolver.resolveData(glbUri);
       if (!defined(resolvedGlbData)) {