Fizz

A colorful bouncing ball simulator with high reproducibility and configurable physics parameters

See the video demo

Performs broad-phase collision detection using the sweep and prune algorithm on axis-aligned bounding boxes.

The force of gravity, coefficients of restitution (that is, the bounciness of the objects) and the ball radii are configurable.

SFML is used for graphics display.

The project was built in Visual Studio 2019.

Controls

• Quit the simulation using the 'q' key
• Enable/disable gravity using the 'g' key
• Add an object by clicking on the screen
• Fire an object with an initial velocity by pressing 'f', and clicking then dragging on the screen, then clicking again
• Add a stream of objects by holding 's' and dragging the mouse
• Enable/disable the top wall using the 't' key
• Pause/unpause simulation using the 'p' key
• Reset all objects to their initial position using the 'r' key
• Show/hide physical constants and current fps using the 'h' key

Configuring physical constants

The constants for gravity and coefficients of restitution can be edited via the configuration box.

1. Open the box by typing 'shift-;'

2. Then type 'param value', such as 'g 0.002' to change the value of a parameter

Available parameters:

• g - constant of gravitational acceleration
• rad - radius of circle objects to be inserted
• ob - object-to-object coefficient of restitution
• bo - boundary-to-object coefficient of restitution

Building the project

The project was built in Visual Studio 2019 on Windows 10.

The following .dll files are required:

openal32.dll
sfml-audio-2.dll
sfml-audio-d-2.dll
sfml-graphics-2.dll
sfml-graphics-d-2.dll
sfml-network-2.dll
sfml-network-d-2.dll
sfml-system-2.dll
sfml-system-d-2.dll
sfml-window-2.dll
sfml-window-d-2.dll

And the font files in assets/fonts folder:

cour.ttf
courbd.ttf

It can also be built on linux: cd fizz mkdir build cd build cmake .. -DCMAKE_BUILD_TYPE=Release cmake --build .. ./Fizz

Useful links

This is a collection of links that were helpful in learning how to program a nice simulation:

• Fixed time step: https://gafferongames.com/post/fix_your_timestep/
• Game loop: http://gameprogrammingpatterns.com/game-loop.html
• Stopping bodies from sinking into the ground: https://gamedev.stackexchange.com/questions/114728/how-to-stop-sinking-bodies-in-physics-engine-c
• Collision detection: https://www.toptal.com/game/video-game-physics-part-ii-collision-detection-for-solid-objects
• Collision detection/resolution: https://www.randygaul.net/2013/03/28/custom-physics-engine-part-2-manifold-generation/
• Collision resolution: http://www.cs.uu.nl/docs/vakken/mgp/2014-2015/Lecture%207%20-%20Collision%20Resolution.pdf