The parameters of each curve are listed in a config file of a quest chapter, which is usually located at /path/to/minecraft/config/ftbquests/quests/chapters/.
When you create a dependency between two quests, the mod automatically creates a curve with parameters [0, 0, 0, 0] and writes it to the config file. Just try to change the parameters and see what will happen to the curve, or look at the picture below. To make the changes appear in the game you may need to reload ftbquests with the command: /ftbquests reload.
Dependencies are represented as cubic Bezier curves.
Each curve has four parameters. The first two of them represent the X-coordinates along the line between two quests in units of a distance between these quests. The zero-point is located at the position of the dependant quest. The last two parameters represent the Y-coordinates along the line perpendicular to the X axis, in units of a half-width of a dependency line and with a zero-point also located at the position of the dependant quest.
