My own simple physics simulator and bridge builder game written in Pygame

Inspired by polybridge and its clones, I wanted to have a go at a bit of physics simulation

This project started as a final assignment for a course at school.

However, I enjoyed working on it so much that it ended up going far beyond the original scope.

Game overview:

• You play as an infrastructure contractor company "Mostex".
• Your job is to construct bridges using the limited budget and ensure fatalities on 'opening day' stay within limits.
• You can use different beam types for your bridge, all of which have different prices and physical properties.
• You need to provide a path for the incoming cars using paved beams.
• The cost of a single beam scales as a square of its length - so build small - but remember that every node adds weight!

Controls:

• Left Mouse button (point & click) - selecting a node for beam construction & menu interactions.
• Right Mouse button (click) - cycle through the available beam types.
• Control + Left Mouse button (point & click) - deleting a node & cancelling beam creation.
• Control + "Z" Key - undo creation of the last beam.

Some screenshots:

Home Screen

Level 1

Underlying physics objects made visible

Physics overview:

It all operates based on a system of Nodes and Beams:

• Nodes are physical points with mass, inertia, and gravity.
• Beams convey forces - they have a set default length and will apply forces to nodes, depending on if they are in tension or compression.
• Beams will change color depending on the force applied:
  • 🔵 Blue: At rest
  • 🟢 Green: In tension
  • 🔴 Red: In compression
• Each Beam exists between two Nodes and keeps a reference to both.
• On top of the compression/tension system is a basic collision detector needed for driveable paved beams - a "wheel" node will collide with any paved beam.

How to get and run:

git clone https://github.com/woyard/Mostex
pip3 install pygame
cd ./Mostex
python3 main.py

Note on architecture:

The code is split into multiple files, but I left a large degree of intercommunication between the component modules. So it needs to load a reference to a 'game' handler for most other objects, at least for painting stuff to display.

This probably isn't the best way of doing this, but doing it another way would require a rewrite of a lot of code, and since it works, I just decided to leave it as-is.