Again, Darvince, it takes tons of work. I'll give you the steps just making one new province:
default.map
- The 2 variables here that you will want to alter are max_provinces and sea_starts. Max_provinces should be set to the number of total land and sea provinces + 1 (for PTI). Sea_starts is the province number of the first sea province.
definitions.csv
- Each province is defined by a unique RGB color value that is defined in this file. Either create one yourself, or use one of the numerous extras provided by Paradox at the end of the file. This is also the final file that contains province numbers, so alter them as you did in text.csv and the history/provinces files.
adjacencies.csv
- This file determines which straits can be crossed over without ships. If you plan to alter or create any such straits, alter this file accordingly.
continent.txt
- This file associates provinces with continents, which determines such things as which advisors you have access to. Enter any new provinces appropriately.
provinces.bmp
- Each province in the game is shown on this map in its unique RGB color as listed in definitions.csv. Make your changes to the map, coloring your new provinces according to the appropriate RGB value, and doing your best not to unknowingly alter any existing provinces that you didn't intend to change. It's worth noting that some sea zones have RGB values so close together that they can not be distinguished by eye. The game scans this file and attempts to create a province for each color it encounters, so even a subtle error here can make your map refuse to load, since it will think a stray pixel is a new province. I've heard that you can check that things are okay by finding the total number of unique colors in the file (which should be total provinces + 1), but have not done this myself. If you are trying to find a stray pixel, my recommendation to you is to use the paint bucket tool set to tolerance 0, anti-alias off and contiguous on and start filling in black around the area that you have been working. Obviously you should save before you start doing this.
minimap.dds
- This file (along with minimap_bg.dds which should be edited by just copying information over from this file) can be found in gfx\interface, and determines what is displayed on the minimap that shows up in the lower right part of the display. Its fairly abstract so I did not edit it myself, but I see no reason why you couldn't treat it like either of the other .dds files.
positions.txt
- This annoying file will, depending on how much of a perfectionist you are (and how small your provinces are), take a long time to get straight. It determines where cities, ports, units, etc., show up on the game map. You can get a rough idea as to what values to use by opening provinces.bmp and clicking on the info tab next on top of the navigator window in the upper right of Photoshop. Click on the left of the X Y Coordinates box that appears and choose points as a measurement unit. That box will now display the coordinates currently being pointed at by the mouse. In theory, that works fine. In practice, you'll have to load up EU3, take screenshots of the map in-game to see how it looks, then alter positions.txt appropriately. The reason I suggested skipping topology.bmp earlier is because it can be easier to place things when everything is flat. Oh, and you can't flip and rotate provinces.bmp while you're doing this because it screws with the coordinates. And everytime you make a change EU3 will recalculate all the paths when loading. So all this can be very time consuming.
One last note on positions.txt. The port_rotation and text_rotation entries in the file determine the direction of ports and province names in game. The value these entries take is the angle as measured in radians from due west. No problem, right? Using the ruler tool in Photoshop we can just determine what angle we want to use, right? Not quite. From what I've been able to determine on-line, there's no way to make Photoshop report angles in radians. Also, Photoshop measures angles from due east (not due west like EU3) and has a maximum value of 180 degrees before switching to negative numbers, whereas radians work on the full 360.
So here's the formula you'll want to use to convert the degrees Photoshop gives you to the value you put into positions.txt:
radians = (-1 * (degrees - 180)) * 0.0174533
The radians used for text_rotation are flipped along the x axis (so a line of text running from NW to SE on the map uses the value you'd expect for one running SW to NE), so take that into account.
Or as a shortcut just use these values:
port_rotation=0.000000 = W
port_rotation=0.785398 = NW
port_rotation=1.570796 = N
port_rotation=2.356194 = NE
port_rotation=3.141593 = E
port_rotation=3.926991 = SE
port_rotation=4.712389 = S
port_rotation=5.497787 = SW
text_rotation=0.785398 = from SW
text_rotation=0.392699 = from WSW
text_rotation=0.000000 = from W
text_rotation=5.890486 = from WNW
text_rotation=5.497787 = from NW
I should probably also mention that province names are centered (not begun) on the value that you enter for text_position.