anyone know what the mapgen.exe is?

so i was looking through starbound's files and I stubbled acrossed a mapgen.exe file and when i run it it generates an image of a new planet's structure. any ideas?

the planet type is "moon"

 

The name itself says it all. It's a executable that randomly generates the planet's structure. The planets in this game are randomly generated and created upon your first visit on a coordinate. For example then you can find the planet in your game data and delete then when you visit the same coordinate it will generate a new planet that looks completely different. The creation of planets it's basically infinite, well until you run out of data space but considering files barely take up anything it wont happen any time soon, at least not in your lifetime. Unless you run this game off of a USB stick with barely any space available. Then again playing like that would be impossible so yeah...

 

Hello Starbound forums, long time no see!

The program is actually useful to people who wish to alter planets generation. When you modify terrestrial_worlds.config (you'll need to unpack it, see https://starbounder.org/Modding:Basics ) and run the program with options, the mapgen.png file changes accordingly, showing you how the biomes and ores are placed.
You can see the options by running the program in a terminal/command prompt window (like this : https://www.digitalcitizen.life/7-ways-launch-command-prompt-windows-7-windows-8 ) and play with them.

For example (tested on the Linux version) :

./planet_mapgen -coordinate 554755309:421570451:-138930377:5 -size 6000,5000
This generates a max 6000x5000 pixels image of the planet at the above coordinates (in this case, taken from my own "universe" folder, file 554755309_421570451_-138930377_5.world).
As I mentioned, if you tweak terrestrial_worlds.config, the result will be different.

./planet_mapgen -help
This displays the available options :
planet_mapgen: Generate a WorldTemplate and output the data in it to an image

Command Line Usage: planet_mapgen [-help] [-version] [-bootconfig <bootconfig>] [-logfile <logfile>] [-loglevel <level>] [-quiet] [-verbose] [-runtimeconfig] [-coordinate <coordinate>] [-coo
rdseed <seed>] [-size <size>] [-weighting] [-weightingblocknoise] [-transition]
-help - Show help text
-version - Print version info
-bootconfig <bootconfig> - Boot time configuration file, defaults to sbinit.config
-logfile <logfile> - Log to the given logfile relative to the root directory, defaults to no log file
-loglevel <level> - Sets the logging level (debug|info|warn|error), defaults to Error
-quiet - Do not log to stdout, defaults to false
-verbose - Log to stdout, defaults to true
-runtimeconfig - Sets the path to the runtime configuration storage file relative to root directory, defauts to no storage file
-coordinate <coordinate> - coordinate for the celestial world
-coordseed <seed> - seed to use when selecting a random celestial world coordinate
-size <size> - x,y size of the region to be rendered
-weighting - Output instead the region weighting at each point
-weightingblocknoise - apply layout block noise before outputting weighting
-transition - show biome transition regions

On Windows the commands will probably be slightly different, probably something like (someone on Windows may confirm?) :
mapgen.exe -help

As a side note, if you do make a terrestrial_worlds.config.patch file, be careful not to launch the game inadvertently without removing the mod first, unless you want your newly discovered planets to follow the rules you've tested.