In the ID you have to specify the image file for each piece. What color the pieces in these images have is entirely up to the creator of the images. You could make a rainbow army if you wanted.
The ID does assume there are only two players, and that the names of the images for one player start with the whitePrefix, and for the black player with the blackPrefix. It doesn't know neutral pieces. If you don't use the AI that is never a problem, as turn order is not enforced, so each piece can be moved at any time, no matter which player the ID thinks it belongs to. So you can just define an extra piece type, e.g. only existing for white, and put that on the board.
For the AI it would be a problem, though. With extra programming one could alter the AI's functions that perform and take back the move such that they would also flip the ownership of the neutral piece, such that the player on move will always be allowed to move it. (And use the same image of a deviating color for both the black and the white player.)
In the ID you have to specify the image file for each piece. What color the pieces in these images have is entirely up to the creator of the images. You could make a rainbow army if you wanted.
The ID does assume there are only two players, and that the names of the images for one player start with the whitePrefix, and for the black player with the blackPrefix. It doesn't know neutral pieces. If you don't use the AI that is never a problem, as turn order is not enforced, so each piece can be moved at any time, no matter which player the ID thinks it belongs to. So you can just define an extra piece type, e.g. only existing for white, and put that on the board.
For the AI it would be a problem, though. With extra programming one could alter the AI's functions that perform and take back the move such that they would also flip the ownership of the neutral piece, such that the player on move will always be allowed to move it. (And use the same image of a deviating color for both the black and the white player.)