This is a simple constraint solver 2D physics engine

Made with the Usagi engine

Running the game

Download Usagi and then you can run the program like so ./usagi run

General controls

• space: To pause or unpause the simulation
• A/D or Left/Right: To switch tools
• 1 ... 9: To load blueprints (1: rectangle, 2: polygon, 3: rope)
• LMB: Use the selected tool
• RMB: Use the selected tool (secondary mode)

Tools

• Ball placer

  Description

  This tool allows you to place balls (nodes) in the world. Each ball has a radius and a mass.

  Controls

  • Left click to place a ball
  • Right click on a ball to delete it

• Selection tool

  Description

  This tool allows you to select balls for further action

  Controls

  • Left click and drag: area selection
  • Right click on a ball: Select the whole creation this ball is connected to
  • [Delete] or [Backspace]: Remove selected balls

• Move tool

  Description

  This tool allows you to move the selected balls

  Controls

  • Left click and drag: MOve balls (even in simulated mode)
  • Right click and drag: Teleport balls on release

• Pin tool

  Description

  With this tool, you can fix balls in place

  Controls

  • Left click on a ball: Pin ball to at current position
  • Right click on a ball: Remove pinning

• Animation tool [WIP]

  Description

  This tool allows you to add animations to a ball. (Like rotation, or mouse following)

  Controls

  • Left click on a ball: Add selected animation
  • Right click on a ball: Remove selected animation

• Connect tool

  Description

  This tool allows you to create connections (distance constraints) between balls

  Controls

  • Left click on a ball: Start creating a connection, left click on a ball again to finish it
  • Right click on a connection to delete it