Im stuck developing an important detail of my game water: Making it flow downwards!
Considering a typical 3D world in wich water tends to go towards gravity
g=(0,-1,0) , and having the normal of the water surface
n=(x,y,z), how can I calculate, based on that, the water flow direction vector?
As an example, consider this badly-done graph (In 2D, though)
Update: I'm considering a very simplified water surface (Just a plane: No ripples, no waves, no pressure, etc.). If any of those needed to be applied, the answer would depend on more factors than just the normal.