[Freeciv-Dev] Re: Isometric mode screen updates.

[Jason Short <vze2zq63@xxxxxxxxxxx>]

Teemu Kurppa wrote:

> I added support for tile markers for GTK-client isometric mode. There are
> some problems in updating map canvas correctly. I have browsed code to
> understand correctly, how drawing in isometric mode is done. But it would
> be great help, if there exists some short introduction to
> the implementation philosophy of isometric mode. Is there ? 
Not AFAIK.  For the most part the isometric changes are spread out and 
gui-specific.  Some of them have been unified.
Here's a start:  when you call get_canvas_xy it will take your map 
position and give you a canvas position.  This canvas pos is the 
top-left corner of the bounding box for the iso-tile; that is:
______
| /\ |
|/  \|
|\  /|
|_\/_|

the top-left corner is the canvas pos for the tile.  The interior 
rhombus is the iso-tile.  NORMAL_TILE_WIDTH and NORMAL_TILE_HEIGTH are 
the dimensions of the bounding box.
I don't know much about the actual drawing code.  I think it uses the 
sptite listings similarly to the flat-view code, but because the tiles 
can overlap (a pretend 3-d effect even though the view is from overhead) 
they must be drawn in a particular order.  Therefore when you update one 
tile you must (I think) update parts of the ones around it.

jason