The Physics behind Video Games
By Laurin Fisher
Nov
26
Swimming
Swimming is a mechanic that is often hard to implement or avoided entirely.
In fact a lot of game developers find implementing swimming not worth it. It tacks more time onto the game, increases difficulty, and a lot of people don't find swimming fun.
A lot of players don't like swimming mechanics because of the lack of control, the slowness of the character, having to keep track of not drowning (which can be stressful in sonic games). Players also find swimming levels to be dreaded because it is extremely boring (swimming forever). So in games, swimming is taken care of in different ways.
0. No swimming-
The character dies upon contact (Smash Bros 3DS) or the character cannot ever interact with water (Animal Crossing).
1. Basic swimming-animation only
Another option would be to only change the character animation and nothing else. The first Mario game I made I did swimming as animation only (picture shown below). All I did was check if Mario collided with the water and then changed his sprite image and animation-the gravity and everything was the same, so he wasn't any slower.
The only reason this worked is because it was only shown to biased family members, not the general public, so I wouldn't recommend this at all, but it's there.
2. Realistic swimming-drag and Newton's laws
Now if you want your game to have real swimming, not cheap swimming as shown above, the best way to do so is to add some realistic physics into your game, the physics of swimming. So let's learn some physics!
--Newton's laws--
Newton's second law states that an object with a mass that has forces acting on it will have an acceleration. This is stated as the equation F=ma. Where F is the force in a given direction, m is the mass of the object, and a is the acceleration in the force's same direction. (Usually F is the net force which is the sum of all forces acting on the object.)To show the forces acting on an object in water we can draw something called a free body diagram, which is a picture of the object and the forces acting on it.
--Free Body Diagram--
As we can see, an object in water has 4 forces acting on it, buoyancy, gravity, drag, and the object's own force of motion (which direction the character is swimming).
Further reading