Making addons for Simutrans can't be impovised but is very easy once the method is known. This complete tutorial will guide you step by step to create objects for Simutrans.
If you have any question contact me (Gauthier) on the Simutrans'forum by creating a new topic or directly by private message on this
We are definitly dealing with objects creating for Simutrans, this tutorial doesn't learn how to modify the game in its code but to create objects like vehicles, buildings, etc … To modify the game you have to learn C++ and modify the code which is opensource.
This tutorial is composed of four parts :
To recap the work needed to create an addon : you have to draw, by a drawing software (pixel-art), by a 3D software or by hand drawing and scan only for pakHD. Then you have to write a text file with all the object's data and the source picture indications, and pak the object with makeobj if everything is right.
The two main methods to have a source picture are the pixel-art and the 3D. For a beginner, 3D looks much more interesting but be carefull ! Using 3D is more difficult than it seems to be, it needs patience, even more if it's used for Simutrans so you have to manage well the detail level and some other things. Of course if you know how to use 3D, the result is very good.
However pixel-art isn't very easy but is easier to learn than 3D. If you never did any 3D, you should rather begin with pixel-art.
You need makeobj to pak objects for Simutrans, download here.
A simple text editor like windows'notepad, notepad++ or linux's gedit is good to write .dat files. It's necessary to be a simple text like .txt files but we will save it as .dat files.
The source pictures are 24 bits .png pictures, you can make them with 3D or with pixel-art.
Now you're ready. There are both a 3D tutorial using google sketchup and a pixel-art tutorial using Photofiltre (both softwares are free). There's also a 3D tutorial using Blender on the Simutrans forum.