Jelly Physics Sandbox

A simple interactive 2D physics sandbox that simulates soft body "jelly" objects using Box2D and SDL2.

Jelly objects are made from circular bodies connected with spring-like distance joints Interactive Manipulation: Click and drag individual jelly nodes to move them around Physics Controls: Adjustable joint stiffness, damping, and gravity Multiple Jellies: Spawn and manage multiple jelly objects simultaneously Real-time Rendering: Visual feedback with nodes, joints, and filled blob approximation

Requirements

Dependencies

• CMake
• Box2D
• SDL2

Installing Dependencies

Windows

Using vcpkg (recommended):

vcpkg install box2d sdl2

Or download pre-built libraries:

• Box2D: https://github.com/erincatto/box2d
• SDL2: https://www.libsdl.org/download-2.0.php

Linux (Ubuntu/Debian)

sudo apt-get install libbox2d-dev libsdl2-dev cmake build-essential

Building

Using CMake

# Create build directory
mkdir build
cd build

# Configure (adjust paths if needed)
cmake .. -DCMAKE_TOOLCHAIN_FILE=[path to vcpkg]/scripts/buildsystems/vcpkg.cmake

# Build
cmake --build .

# On Windows, you may need to copy SDL2 DLL to the build directory

Keyboard

• N - Spawn a new jelly at the center
• D - Delete the last jelly
• C - Clear all jellies
• R - Reset (clear all and spawn one jelly)
• G - Toggle gravity on/off
• SPACE - Pause/Resume simulation
• S - Step one frame forward (when paused)
• UP/DOWN - Increase/Decrease joint stiffness
• LEFT/RIGHT - Decrease/Increase joint damping
• ESC - Quit

Mouse

• Left Click + Drag grab and move individual jelly nodes
• Right Click spawn a new jelly at mouse position
• Mouse Wheel - adjust joint stiffness