Send an array of struct to compute shader

Question

I am using Unity to send two types of data to the Compute Shader:

A struct:

struct Flock
{
    public Vector3 position;   
    public Vector3 velocity;   
}

And an Array of the above struct.

C# Code:

Flock[] ComputeFlock()
{
    Flock[] output = new Flock[Amount];

    int kernel = FlockComputeShader.FindKernel("MoveFlock");

    // Flock struct
    int size = sizeof(float) * 3 + sizeof(float) * 3;
    ComputeBuffer buffer = new ComputeBuffer(_flockAI.Length, size);
    buffer.SetData(_flockAI);

    FlockComputeShader.SetBuffer(kernel, "dataBuffer", buffer);

    // Flock array
    ComputeBuffer neighboursBuffer = new ComputeBuffer(_flockAI.Length, size * _flockAI.Length);
    neighboursBuffer.SetData(_flockAI);
    FlockComputeShader.SetBuffer(kernel, "neighbours", neighboursBuffer);

    FlockComputeShader.Dispatch(kernel, _flockAI.Length / 16, 1, 1);
    buffer.GetData(output);
    buffer.Dispose();

    return output;
}
                 

Compute Shader:

#pragma kernel MoveFlock

struct FlockVec3Float
{
    float3 position;
    float3 velocity;
};

RWStructuredBuffer<FlockVec3Float> dataBuffer;

StructuredBuffer<FlockVec3Float> neighbours[1024];

[numthreads(16,1,1)]
void MoveFlock(uint3 id : SV_DispatchThreadID)
{
    for (uint i = 0; i < 1024; i++) {
        dataBuffer[id.x].position.xyz = dataBuffer[id.x].position.xyz + neighbours[i].position.xyz;
    }
}

I am trying to implemented a form of boids algorithm in the compute shader. The struct is the boid and the array of structs is to identify positions of it's neighbours. What I can't figure out is how I can send the full array of struct to the shader and have it iterate over it.

I can send the struct and have the shader read and write to it without any issues. Can someone point out what I might be doing wrong? I am wondering if it is something to do with the stride in the buffer. Thanks!

Answer 1

For anyone that might have a similar question, here's how I iterate over the buffer:

uint _length;
uint _stride;

Buffer.GetDimensions(_length, _stride);

for (uint i = 0; i < _length; i++)
{
    Buffer[i];
}
```