Target Simulator

A real-time 2D interceptor simulation built with C++ and SFML, demonstrating proportional navigation for target tracking.

Overview

This project simulates a guided interceptor tracking and pursuing a moving target using proportional navigation guidance. The interceptor adjusts its trajectory based on the rate of change of the line-of-sight angle to the target, creating realistic pursuit behavior.

Features

• Proportional Navigation: Implements a proportional navigation algorithm where the interceptor's turn rate is proportional to the line-of-sight angle rate
• Visual Trail Effects: Interceptor leaves a smoke trail showing its flight path
• Dynamic Target: Target bounces around the screen with randomized velocity
• Interactive Launch: Right-click to launch the interceptor toward the current target position
• Collision Detection: Simulation pauses when the interceptor reaches the target

Requirements

• C++20 or later
• SFML 3.0+ (Graphics module)

Building

# Clone the repository
git clone https://github.com/14yashh/target-simulator.git
cd target-simulator

# Build with g++:
g++ main.cpp -lsfml-graphics -lsfml-window -lsfml-system -o interceptor

# Run
./interceptor

Note: This code uses SFML 3.0 features that require C++20. Most modern compilers default to C++20, but if you encounter issues, add -std=c++20 to the compile command.

Usage

• Right Click: Launch interceptor toward target (also randomizes target velocity)
• ESC: Close the window
• The simulation pauses when the interceptor hits the target
• Launch again with another right-click to restart

How It Works

Proportional Navigation

The interceptor uses proportional navigation guidance, a technique commonly used in guided systems. The key principle:

• Calculate the line-of-sight (LOS) angle from interceptor to target
• Measure the rate of change of this angle (dλ/dt)
• Command a turn rate proportional to this rate: turn_rate = N × dλ/dt

When the LOS angle rate approaches zero, the interceptor is on a collision course with the target.

Physics

• Acceleration: 200 units/s²
• Max Speed: 400 units/s
• Navigation Constant: 4.0 (controls aggressiveness of turns)

Project Structure

.
├── .gitignore              # Git ignore rules
├── main.cpp                # Main application loop and event handling
├── interceptor.h           # Interceptor class with guidance logic
├── target-simulator.gif    # Demo animation
└── README.md               # This file

Technical Details

The simulation runs at 60 FPS and uses delta time for frame-independent physics. The proportional navigation implementation includes angle wrapping to handle the discontinuity at ±180°, ensuring smooth guidance through all quadrants.

Acknowledgments

Built with SFML - Simple and Fast Multimedia Library