As mentioned in #720, we want to convert the old SLP terrain files to a flat terrain texture. I've implemented a working prototype for that utilizing the dimetric projection algorithm from the openage modding repository. The resulting python script can be found here. It operates on the output of our current converter.

merge() puts the single tiles together into one giant tile. transform() projects the result from dimetric to the desired flat perspective. Here you see the output when converting 15006.slp.png.

Textures from SLPs will always have a ratio of 1:1 and a size of 481x481 (compared to 512x512 in HD).

If somebody want to implement a more efficient version of the script and integrate it into the converter, go ahead.