SPZ writing, exporting, & viewer. Creates a new npm run to-spz which runs scripts/to-spz.js to convert any Gsplat input file to compress .spz. Also includes a configurable viewer examples/viewer that can load splats via drag-n-drop, from url query param, the URL text list, can edit sets of SplatMesh, and export composite .SPZ with some filters. Refactored some loading code from worker.ts to loader files so they can be called from Nodejs. Created api transcodeSpz with options to combine multiple source Gsplat files into one without losing coding quality along the way.

src/antisplat.ts

@@ -0,0 +1,120 @@
+import { computeMaxSplats, setPackedSplat } from "./utils";
+
+export function decodeAntiSplat(
+  fileBytes: Uint8Array,
+  initNumSplats: (numSplats: number) => void,
+  splatCallback: (
+    index: number,
+    x: number,
+    y: number,
+    z: number,
+    scaleX: number,
+    scaleY: number,
+    scaleZ: number,
+    quatX: number,
+    quatY: number,
+    quatZ: number,
+    quatW: number,
+    opacity: number,
+    r: number,
+    g: number,
+    b: number,
+  ) => void,
+) {
+  const numSplats = Math.floor(fileBytes.length / 32); // 32 bytes per splat
+  if (numSplats * 32 !== fileBytes.length) {
+    throw new Error("Invalid .splat file size");
+  }
+  initNumSplats(numSplats);
+
+  const f32 = new Float32Array(fileBytes.buffer);
+  for (let i = 0; i < numSplats; ++i) {
+    const i32 = i * 32;
+    const i8 = i * 8;
+    const x = f32[i8 + 0];
+    const y = f32[i8 + 1];
+    const z = f32[i8 + 2];
+    const scaleX = f32[i8 + 3];
+    const scaleY = f32[i8 + 4];
+    const scaleZ = f32[i8 + 5];
+    const r = fileBytes[i32 + 24] / 255;
+    const g = fileBytes[i32 + 25] / 255;
+    const b = fileBytes[i32 + 26] / 255;
+    const opacity = fileBytes[i32 + 27] / 255;
+    const quatW = (fileBytes[i32 + 28] - 128) / 128;
+    const quatX = (fileBytes[i32 + 29] - 128) / 128;
+    const quatY = (fileBytes[i32 + 30] - 128) / 128;
+    const quatZ = (fileBytes[i32 + 31] - 128) / 128;
+    splatCallback(
+      i,
+      x,
+      y,
+      z,
+      scaleX,
+      scaleY,
+      scaleZ,
+      quatX,
+      quatY,
+      quatZ,
+      quatW,
+      opacity,
+      r,
+      g,
+      b,
+    );
+  }
+}
+
+export function unpackAntiSplat(fileBytes: Uint8Array): {
+  packedArray: Uint32Array;
+  numSplats: number;
+} {
+  let numSplats = 0;
+  let maxSplats = 0;
+  let packedArray = new Uint32Array(0);
+  decodeAntiSplat(
+    fileBytes,
+    (cbNumSplats) => {
+      numSplats = cbNumSplats;
+      maxSplats = computeMaxSplats(numSplats);
+      packedArray = new Uint32Array(maxSplats * 4);
+    },
+    (
+      index,
+      x,
+      y,
+      z,
+      scaleX,
+      scaleY,
+      scaleZ,
+      quatX,
+      quatY,
+      quatZ,
+      quatW,
+      opacity,
+      r,
+      g,
+      b,
+    ) => {
+      setPackedSplat(
+        packedArray,
+        index,
+        x,
+        y,
+        z,
+        scaleX,
+        scaleY,
+        scaleZ,
+        quatX,
+        quatY,
+        quatZ,
+        quatW,
+        opacity,
+        r,
+        g,
+        b,
+      );
+    },
+  );
+  return { packedArray, numSplats };
+}