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Update sort algorithm wording in docs #382

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Update sort algorithm wording in docs
mikeyzhong Jun 26, 2026
0bda31c
Refine sort docs wording
mikeyzhong Jun 26, 2026
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4 changes: 2 additions & 2 deletions docs/docs/system-design.md
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Expand Up @@ -6,7 +6,7 @@ One of the biggest challenges in real-time Gaussian splat rendering is sorting t

`SparkRenderer` is a key component in Spark that manages this process. It traverses the visible THREE.js scene graph and compiles a complete list of all splats across the scene, generated by instances of `SplatMesh` in the scene hierarchy.

Each `SparkRenderer` has a default `SparkViewpoint` that reads back a list of all splat viewpoint distances from the GPU, then determines the splat draw order using an efficient bucket sort algorithm, run in a background worker thread via `SplatWorker`. You can spawn additional `SparkViewpoint`s to create multiple simultaneous render viewpoints.
Each `SparkRenderer` has a default `SparkViewpoint` that reads back a list of all splat viewpoint distances from the GPU, then determines the splat draw order using an efficient radix sort algorithm, run in a background worker thread via `SplatWorker`. You can spawn additional `SparkViewpoint`s to create multiple simultaneous render viewpoints.

Finally, on the next THREE.js render() call, `SparkRenderer` invokes a single instanced geometry draw call to draw all the scene's splats in the correct back-to-front order, merging with other opaque THREE.js geometry using the Z buffer. The sort order lags the render by at least one frame, but possibly more on older devices, but is not usually perceptible.

Expand All @@ -26,4 +26,4 @@ Spark also uses this opportunity to run a user-programmable data pipeline on eac

In contrast, implementing a `SplatGenerator` gives you full control to write any function that programmatically computes a splat's attributes (center, scales, quaternion, rgba). These could be stateless (relying only on `index`, random-number generators, etc), or could rely on a complex combination of splat files, textures, and other global parameters for real-time procedural generation, and can vary with time to produce real-time animations.

The `dyno` shader graph system allows you to create these programmatic pipelines with Javascript code, which is synthesized into GLSL code and compiled and run on the GPU. This `dyno` system powers other components of Spark as well, such as `Readback` (which can perform any computation and read back the resulting value), used to compute the sort distance metric for pairs of splats and read them back for CPU sorting.
The `dyno` shader graph system allows you to create these programmatic pipelines with Javascript code, which is synthesized into GLSL code and compiled and run on the GPU. This `dyno` system powers other components of Spark as well, such as `Readback` (which can perform any computation and read back the resulting value), used to compute the sort distance metric for pairs of splats and read them back for CPU sorting.
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