Why Y coord have decrease as this go up (offset, objects position) ?

[webrobot1]

A lot of system have:

as Y go up it will be increase, but tiled have another reaction. As example look how MYSQL see polygon from example map (Unity engine have a same coord's system)

If start poin is 0, 0 all what will be lower foк Y must be decrease, not increase as in Tiled

And like example is standart coord grill (up is increase, tiled have decrease)

[bjorn]

A lot of system have:

While that's true, a lot of other systems (especially GUI applications and 2D rendering APIs) use a downwards Y axis with 0,0 in the top-left. See for example the coordinate system used by QPainter, GTK, Java Swing and 2D API, LÖVE's coordinate system, SDL's rects, Allegro, CSS object model, etc.

The Y axis going down means Tiled uses a left-handed coordinate system. It's not right or wrong, it just needs to be taken into account when rendering Tiled maps using a framework with a right-handed coordinate system.

There is an issue open about supporting an inverted Y axis in Tiled (#249), however its most recent implementation (#2040) is a little stuck because inverting the Y axis is not just a display change, but also affects object origins and should possibly even affect the direction of the rotation. It's unclear to me whether it is really worth supporting.