emmetot / buffersorter

This is a very simple tool for in-place sorting of ComputeBuffers of ints on the GPU, meant for use in Unity.

BufferSorter

This is a very simple tool for in-place sorting of ComputeBuffers of ints or uints on the GPU, meant for use in Unity. I wrote this to use with a basic GPU particle system I'm working on, which needs to always be sorted consistently between frames.

This is based on the great work of nobnak, available here. I simply wanted to make it a little more user friendly for my own needs. The fundamental sorting algorithm is their own work.

My additions are:

• It now works in-place, changing the data in the given ComputeBuffer to be sorted.
• The data buffer no longer needs to have a power of two size.
• You can optionally sort in reverse.
• You can provide a distinct buffer containing sort keys if you want custom sorting behaviour.
• You can optionally sort only a subset of the data, the first of N. Note that this option completely disregards the content of the remainder of the buffer, so it could be considered 'destructive' in that the set of ints will no longer be the same.
• I've generally just hidden a lot of the extra bits and bobs away inside the class, making it very simple to use from the outside.

How to Use

Like this:

It couldn't be simpler, really. Reverse, sublist length, and sort key buffer are optional parameters.

The project included is Unity version 2020.3.0f1, but there's nothing in the project other than the C# file and compute shader (as well as some unit tests in a demo script), and nothing especially version dependent. Just copy the scripts and meta files over and you're good to go.

buffersorter's Issues

doesnt work on vulkan

Hello! I am using this in a unity GPU instancing tool where instances need to be sorted by the distance to the camera. it sorts properly on dx11 and dx12, however on vulkan most of the attempts fail. im using unity 2021.2/3, though i doubt that should matter.