Flocking Boids

This program simulates how fish behave in large groups, run from predators, avoid obstacles, avoid borders, and more.

Note: This version requires Visual Studio. If you do not have access to Visual Studio, here is a version for linux and windows that requires no setup: https://github.com/Zachhi/FlockingBoids-Windows-Linux

Demo

(Quality much worse here due to gif-conversion)

Watch the video here (above is only a 10 second gif): https://www.youtube.com/watch?v=G17Cqs6FFl0&t=18s

About

A major part of this program was to make it look as clean as possible. I focused on having it look professionally done, and I put a lot of thought into the design of the simulation itself. There have been plenty of flocking boid programs done, and I wanted mine to pop out and look better than any others. This simulation is worth a look at, so go ahead and scroll to the Demo section to watch the youtube video.

The base idea comes from Craig Reynolds, who developed a model for flocking in 1986. More can be read here: https://www.red3d.com/cwr/boids/

Flocking Boids considers 3 rules: Seperation, Cohesion, and Allignment

Seperation defines the way boids avoid each other and avoid contact with each other.
Cohesion refers to how the boids group together. They will attempt to move to the average center of mass of the boids around them.
Allignment defines the way boids allign, as they will steer towards the average heading of the boids around them.

The union of these three simple rules gives you incredible flocking behavior. The three rules are each multiplied by a certain coefficient, and changing these coefficients will signifigantly change their behavior.

This is the very simple, very base idea that doesn't do the simulation justice. Scroll down to the demo section and watch the youtube video in order to see the simulation in all its detail

Flocking Types

There are 3 different flocking types provided. The first can be thought of the normal flocking type. Boids stay an average distance apart with an average sight range to each other. In the second type, boids stay very close together, and don't have as much as sight range. This flocking type is very visually pleasing, and looks best when there is no predator chasing them. The third one is my favorite and would probably be considered the most realistic. Boids are much farther apart with a much farther sight range. This leads to bigger groups. This type works best when there are a lot of boids on screen, and it looks the coolest when a predator is on screen. When a predator chases boids that are in flocking type 3, it leads to the most visually pleasing results of the program.

Boid Types

Blue Boid: Has normal movement and rotation speed. Lets the predator get an average distance near them. Then they speed up at an average pace and head away, and slow down once the predator is an average distance away.
Dark Blue boids: A little faster in both movement and rotation. Lets the predator get a little closer to them than the average. Then they speed up at a slower pace and head away, and slow down once the predator is less than the average distance away. These are the easiest to catch for the predator.
Pink Boids: Even faster in both movement and rotation. Lets the predator get really close, much closer than any others. Than they speed up much faster than any other, and they don't slow down until they are really far from the predator. These are the most scattery fish, and the hardest to catch for the predator.
Yellow boids: Fastest in both movement and rotation. Doesn't let the predator get close at all. They run away at a much higher distance than any other boid. They start running before the predator can even detect them. However, when they are being chased, they don't speed up at all.
White Boids: Slowest in both movement and rotation. However, they are not deteced by predators. They still run away when a predator get's close though.

Other

Toggling every rule except cohesion off, and then repeatedly clicking "X" leads to cool effects
Clicking "H" shows the boid's headings. This is where they wish to go according to the 3 rules+predators+borders+repulsions
Repulsions are fun to mess with. It is a stand still obstacle boids wil avoid. Clicking "O" creaes a circle of them. It is interesting to do this, add a bunch of boids inside, then spawn a predator inside.
Changing the game speed can be really satisfying. Right before a predator goes in for the kill, start turning it down. Then you can see in slo-mo the boid's running away.
Mess with it. There are many variants you can do, such as
- Spawning 50 predators and one prey (I reccomend a pink boid for this)
- Spawning 500 boids of different types and seeing how they flock. Add a predator in and watch the chaos. Turn off borders for a less chaotic screen.
- See how boids interact with repulsions in their way. I made it so boids will "wiggle" their way out of them.
- Seeing how one predator will chase one prey
- Seeing how boids behave when different rules are toggled on or off
- Looking at a boids heading while running from a predator or while flocking is very satisfying
- Spawning multiple repulsion circles of different sizes, and adding boids inside of these
- And whatever else you wish

Eventually, my plan is to make this into a screensaver people can download and use.

Animations were drawn myself, The "Clair De Lune" and "Comptine d'un autre été - Amélie" music tracks were performed myself.

Controls

GUI

Top Right: Shows the three rules and which are toggled, the FPS, and the game speed
Bottom Right: Shows the current boid you are spwaning
Bottom Left: Shows the current counts of the boids on screen
Top Left: Shows the rules

Input

LShift: See all the controls (will show in top left)
Left click: Spawn the current boid type (either a prey or predator)
Space: Spawn 20 of the current boid types in random locations
X: Spawn 2 of the current boid types facing each other on opposite sides of screen
Left/Right Arrow Keys: Next/Previous boid type
P: Change current boid type to predator and back
Right Click: Create/delete repulsion
O: Spawn a circle of repulsions
I: Change the type of repulsion circle that will spawn
1: Toggle rule 1 (Separation)
2: Toggle rule 2 (Cohesion)
3: Toggle rule 3 (Allignment)
LTab: cycle to a new flocking behavior
B: Toggle borders on and off
H: Toggle boid headings on and off
C: Clear everything from the screen
V: Clear current object type from the screen
R: Clear all repulsions from the screen
Up/Down Arrow Keys: Increase/decrease game speed (slow-mo or fast-mo)
N: Cycle to next song
LCtrl: Hide GUI
Esc: Exit program

Dependencies

Windows
Visual Studio 19 or above
SFML (Simple and Fast Multi-Media Library) 2.5.1 or later is required in order to run this program. You can install SFML here: https://www.sfml-dev.org/download/sfml/2.5.1/
Since we are using Visual Studio, download the Visual c++ 15 from the sfml website

If you don't have access to Visual Studio, or you are on linux, scroll to the top to find the other version

Installing and Executing

Download the source code from github, or clone the repository into Visual Studio
Import into Visual Studio
Build according to your need (x86 or x64)
In project settings
- Add the /path/to/sfml/include to your c++ include path
- Add the /path/to/sfml/libray to the linker library path
- Link the following sfml libraries: sfml-graphics.lib, sfml-windows.lib, sfml-system.lib, sfml-audio.lib
- Link the following debug libraries: sfml-graphics-d.lib, sfml-windows-d.lib, sfml-system-d.lib, sfml-audio-d.lib
- Copy the sfml dlls (in the sfml/bin folder) to your project folder
A very easy and simple 5 minute tutorial for linking SFML with a Visual Studio project can be found here: https://www.youtube.com/watch?v=YfMQyOw1zik
Click the run button at the top and the program should start

If you would prefer not having to link libraries, and would prefer a version fully set up, see the link at the top

Authors

Zachary Chi zachchi@tamu.edu

License

This project is licensed under the MIT License - see the LICENSE.md file for details

Zachhi/FlockingBoids-VS