#pragma kernel CSLeft
#pragma kernel CSRight
#pragma kernel CSUp
#pragma kernel CSDown

RWTexture2D<float4> _TerrainIndex;
RWTexture2D<float4> _TerrainWeight;
Texture2D<float4> _NeighborIndex;
Texture2D<float4> _NeighborWeight;
StructuredBuffer<float> _Mapping;
int _Width;
int _Height;

float4 Map(float4 i)
{
    uint4 index = (uint4)round(i * 32.0);
    i.x = _Mapping[index.x];
    i.y = _Mapping[index.y];
    i.z = _Mapping[index.z];
    i.w = _Mapping[index.w];

    return i/32.0;
}

[numthreads(512,1,1)]
void CSLeft (uint3 id : SV_DispatchThreadID)
{
    _TerrainIndex[int2(0,id.x)] = Map(_NeighborIndex[int2(_Width, id.x)]);
    _TerrainWeight[int2(0,id.x)] = _NeighborWeight[int2(_Width, id.x)];
}

[numthreads(512,1,1)]
void CSRight (uint3 id : SV_DispatchThreadID)
{
    _TerrainIndex[int2(_Width,id.x)] = Map(_NeighborIndex[int2(0, id.x)]);
    _TerrainWeight[int2(_Width,id.x)] = _NeighborWeight[int2(0, id.x)];
}

[numthreads(512,1,1)]
void CSDown (uint3 id : SV_DispatchThreadID)
{
    _TerrainIndex[int2(id.x, 0)] = Map(_NeighborIndex[int2(id.x, _Height)]);
    _TerrainWeight[int2(id.x, 0)] = _NeighborWeight[int2(id.x, _Height)];
}

[numthreads(512,1,1)]
void CSUp (uint3 id : SV_DispatchThreadID)
{
    _TerrainIndex[int2(id.x, _Height)] = Map(_NeighborIndex[int2(id.x, 0)]);
    _TerrainWeight[int2(id.x, _Height)] = _NeighborWeight[int2(id.x, 0)];
}