// the streamoutbuffer with the coords
ByteAddressBuffer sobCoords;
// the filtered indices
StructuredBuffer<uint> sbIndex;
int elementcount;

RWStructuredBuffer<uint> buffer : BACKBUFFER;

[numthreads(64, 1, 1)]
void CS( uint3 i : SV_DispatchThreadID)
{
    if (i.x >=  asuint(elementcount)) { return;}

    uint idx = sbIndex[i.x];

    float x = asfloat(sobCoords.Load(idx * 24));
    float y = asfloat(sobCoords.Load(idx * 24 + 4));
    float z = asfloat(sobCoords.Load(idx * 24 + 8));
    float w = asfloat(sobCoords.Load(idx * 24 + 12));

    /* some more code here that is irrelevant*/
}