Calculating center of custom tiles?

Question

Problem

How to calculate center of each custom tile as a point (x,y) or (x,y,z) where z is zoom level, in a projection: EPSG:3857?

What I know about the tiles

• Originally they are served as TMS
• They represent png images 256*256
• They are in projection: EPSG:3857
• In OpenLayers2 they were coded like TMS layer
• In OpenLayers3 (v.3.8.2) they are coded like XYZ layer (that includes -y) as shown in this example:

-

  var baseLayer = new ol.layer.Tile({
      source: new ol.source.XYZ({
        url: 'http://path/to/the/tiles/base/{z}/{x}/{-y}.png'
      })
    })

Answer 1

I have finally found answer to this question: https://stackoverflow.com/questions/32046601/convert-xyz-coordinate-of-a-tile-to-longitude-latitude. Thank you very much @Alvin Lindstam!

For future references I just want to mention the meaning of the result:

10, 510, -341 -> 10, 510, -341     <----- z/x/y of tile
-78271.51696402207, 6692214.700423751, -39135.75848200917, 6731350.458905762 <----- first point: left down corner of the tile, second point: right upper corner of the tile
-58703.63772301562, 6711782.579664757 <----- point: center