Really explaining the argument of the painter constructors in hundreds of calls with a bunch of tabs?

What would we have done without these comments...

Can't add an inline comment here for any reason. That loop was useless (if we already add a path from X to Y, then we don't need another from Y to X):

for (m = 0; m < numIslands; m++){
 for (n = 0; n < numIslands; n++){
   if(isConnected[m][n] == 1){
      isConnected[n][m] = 1;
   }
 }
}

unused var

That value is never read from as it is overwritten in each if-statement below

After a too long time, I figured cu = curve

The wrong indentation mislead me to remove a wrong brace and commit a JS syntax error.

Took me only a day of solving equations to come to the conclusion that this is an exact copy of the other dozens of river functions and give those magic numbers human readable names.
That 200.0 had been 1/0.05/10, i.e. fadeDist = 0.005 and 1/fadeDist/10 .
That abs is not present in the other copies because the if determines the sign

That -3 had been some other constant some day, but all the constants were squelched so that noone could recognize them (and thus change them feasibly) anymore.

-> rP20185

Not to speak of 9 pairs of unneeded braces in each of the copies of this line.

copies every mistake from guadalquivir river

No need to compute the angle with that formula, as its just halfway between the two player angles.

isRiver[c][numPlayers] doesn't have to be a two-dimensional array, nor a one-dimensional array.

In this commit there is a river between each neighbor, later it was changed to only add rivers between players. Can just query that, no need to save it in a two dimensional array where one dimension is never used.

No need for an array in thetha, seed, shallowstuff if it can be just determined in the loop below

Only one player loop needed as we only need to compare neighbors, not every player with everyone else.

The playerloop should be the outermost, as everything inside it is about that one river for that one player.

^ mess