// ComputeTransform determines the block coordinate and beginning + ending voxel points
// for the data corresponding to the given Block.
func (v *Voxels) ComputeTransform(block *storage.TKeyValue, blockSize dvid.Point) (blockBeg, dataBeg, dataEnd dvid.Point, err error) {
var ptIndex *dvid.IndexZYX
ptIndex, err = DecodeTKey(block.K)
if err != nil {
return
}
// Get the bounding voxel coordinates for this block.
minBlockVoxel := ptIndex.MinPoint(blockSize)
maxBlockVoxel := ptIndex.MaxPoint(blockSize)
// Compute the boundary voxel coordinates for the ExtData and adjust
// to our block bounds.
minDataVoxel := v.StartPoint()
maxDataVoxel := v.EndPoint()
begVolCoord, _ := minDataVoxel.Max(minBlockVoxel)
endVolCoord, _ := maxDataVoxel.Min(maxBlockVoxel)
// Adjust the DVID volume voxel coordinates for the data so that (0,0,0)
// is where we expect this slice/subvolume's data to begin.
dataBeg = begVolCoord.Sub(v.StartPoint())
dataEnd = endVolCoord.Sub(v.StartPoint())
// Compute block coord matching dataBeg
blockBeg = begVolCoord.Sub(minBlockVoxel)
return
}
