Method sortUpdate

src/OldSparkViewpoint.ts:565–667

({
    accumulator,
    viewToWorld,
    displayed = false,
  }: {
    accumulator?: OldSplatAccumulator;
    viewToWorld: THREE.Matrix4;
    displayed?: boolean;
  })

  }

  private async sortUpdate({
    accumulator,
    viewToWorld,
    displayed = false,
  }: {
    accumulator?: OldSplatAccumulator;
    viewToWorld: THREE.Matrix4;
    displayed?: boolean;
  }) {
    if (this.sortingCheck) {
      throw new Error("Only one sort at a time");
    }
    this.sortingCheck = true;

    accumulator = accumulator ?? this.spark.active;
    const { numSplats, maxSplats } = accumulator.splats;
    let activeSplats = 0;
    let ordering = this.orderingFreelist.alloc(maxSplats);

    if (this.stochastic) {
      activeSplats = numSplats;
      // Render all splats in order since the Z-buffer
      // will handle ordering.
      for (let i = 0; i < numSplats; ++i) {
        ordering[i] = i;
      }
    } else if (numSplats > 0) {
      const {
        reader,
        doubleSortReader,
        sort32Reader,
        dynoSortRadial,
        dynoOrigin,
        dynoDirection,
        dynoDepthBias,
        dynoSort360,
        dynoSplats,
      } = OldSparkViewpoint.makeSorter();
      const sort32 = this.sort32 ?? false;
      let readback: Uint16Array | Uint32Array;
      if (sort32) {
        this.readback32 = reader.ensureBuffer(maxSplats, this.readback32);
        readback = this.readback32;
      } else {
        const halfMaxSplats = Math.ceil(maxSplats / 2);
        this.readback16 = reader.ensureBuffer(halfMaxSplats, this.readback16);
        readback = this.readback16;
      }

      const worldToOrigin = accumulator.toWorld.clone().invert();
      const viewToOrigin = viewToWorld.clone().premultiply(worldToOrigin);

      dynoSortRadial.value = this.sort360 ? true : this.sortRadial;
      dynoOrigin.value.set(0, 0, 0).applyMatrix4(viewToOrigin);
      dynoDirection.value
        .set(0, 0, -1)
        .applyMatrix4(viewToOrigin)
        .sub(dynoOrigin.value)