several fixes to tessellation and extremely fast (in comparison) initial load of CAD objects

src/models/glb/glbs.ts

@@ -1,69 +0,0 @@
-const textDecoder = new TextDecoder();
-
-/**
- * Given a stream of binary data (e.g. from a fetch response), splits a GLBS file into its component GLB files and
- * returns them as a generator of Uint8Arrays (that starts with the expected length).
- * It also supports simple GLB files (no splitting needed).
- */
-export async function* splitGlbs(readerSrc: ReadableStream<Uint8Array>): AsyncGenerator<number | Uint8Array> {
-    let reader = readerSrc.getReader();
-    let [buffer4Bytes, buffered] = await readN(reader, new Uint8Array(), 4);
-    console.assert(buffer4Bytes.length === 4, 'Expected 4 bytes for magic numbers')
-    let magic = textDecoder.decode(buffer4Bytes)
-    if (magic === 'glTF' /* GLB */ || magic[0] == '{' /* glTF */) {
-        yield 1
-        let remaining = await readAll(reader, buffered);
-        // Add back the header to the beginning of the document
-        let finalBuffer = new Uint8Array(buffer4Bytes.length + remaining.length);
-        finalBuffer.set(buffer4Bytes);
-        finalBuffer.set(remaining, buffer4Bytes.length);
-        yield finalBuffer
-    } else if (magic === "GLBS") {
-        // First, we read the number of chunks (can be 0xFFFFFFFF if the number of chunks is unknown).
-        [buffer4Bytes, buffered] = await readN(reader, buffered, 4);
-        let numChunks = new DataView(buffer4Bytes.buffer).getUint32(0, true);
-        yield numChunks
-        // Then, we read the length of each chunk followed by the chunk itself.
-        for (let i = 0; i < numChunks; i++) {
-            // - Read length
-            [buffer4Bytes, buffered] = await readN(reader, buffered, 4);
-            if (buffer4Bytes.length === 0) {
-                if (numChunks != 0xFFFFFFFF) throw new Error('Unexpected end of stream while reading chunk length:'+
-                    ' expected ' + (numChunks - i) + ' more chunks');
-                else break // We reached the end of the stream of unknown length, so we stop reading chunks.
-            }
-            let length = new DataView(buffer4Bytes.buffer).getUint32(0, true);
-            // - Read chunk
-            let chunk: Uint8Array
-            [chunk, buffered] = await readN(reader, buffered, length);
-            yield chunk
-        }
-    } else throw new Error('Invalid magic numbers for expected GLB/GLBS file: ' + magic);
-    reader.releaseLock()
-}
-
-/**
- * Reads up to `n` bytes from the reader and returns them as a Uint8Array.
- * An over-read is possible, in which case the returned array will still have `n` bytes and the over-read bytes will be
- * returned. They should be provided to the next call to `readN` to avoid losing data.
- */
-async function readN(reader: ReadableStreamDefaultReader<Uint8Array>, buffered: Uint8Array, n: number | null = null): Promise<[Uint8Array, Uint8Array]> {
-    let buffer = buffered;
-    while (n === null || buffer.length < n) {
-        let {done, value} = await reader.read();
-        if (done) break;
-        let newBuffer = new Uint8Array(buffer.length + value.length);
-        newBuffer.set(buffer);
-        newBuffer.set(value, buffer.length);
-        buffer = newBuffer;
-    }
-    if (n !== null) {
-        return [buffer.slice(0, n), buffer.slice(n)]
-    } else {
-        return [buffer, new Uint8Array()];
-    }
-}
-
-async function readAll(reader: ReadableStreamDefaultReader<Uint8Array>, buffered: Uint8Array): Promise<Uint8Array> {
-    return (await readN(reader, buffered, null))[0];
-}

src/models/glb/merge.ts

@@ -69,7 +69,7 @@ function dropByName(name: string): Transform {
 function mergeScenes(): Transform {
     return (doc: Document) => {
         let root = doc.getRoot();
-        let scene = root.getDefaultScene();
+        let scene = root.getDefaultScene() ?? root.listScenes()[0];
         for (let dropScene of root.listScenes()) {
             if (dropScene === scene) continue;
             for (let node of dropScene.listChildren()) {