Particle Simulation Breakdown

This is a simple particle simulation where:

• Particles are confined to move within a square box (canvas).
• Particles move and bounce off the walls of the box.
• Particles can also collide with each other and bounce off one another.

Main Parts of the Code:

1. Initialization:

The canvas is fetched and its size is set based on the width of the container. The number of particles, their radius, and speed are set. An array for positions and velocities of the particles is created.

2. initializeParticles function:

This function initializes the positions of the particles randomly within the canvas, making sure they are not too close to the boundaries. The velocities of the particles are set randomly based on the SPEED.

3. updateParticles function:

This function updates the position and velocities of the particles. Boundary collisions are detected, and the velocity is reversed if a particle hits the boundary. Particle-particle collisions are detected and velocities are updated accordingly. A rotation matrix is applied to simplify the calculation of the collision in 1D, and then it's converted back to 2D.

4. drawParticles function:

Clears the canvas and then draws each particle at its current position.

5. mainLoop function:

This is the main animation loop. It calls updateParticles to update positions and velocities and then calls drawParticles to render the particles on the canvas. The requestAnimationFrame method is used to call the mainLoop function again, creating an animation.

6. restartSimulation and updateNumParticles functions:

• restartSimulation: Resets the simulation.
• updateNumParticles: Updates the number of particles based on user input and reinitializes the simulation.

7. Event Listener for Window Resize:

Whenever the window is resized, the size of the canvas is updated, and the particles are reinitialized.

Finally, the particles are initialized and the animation loop starts with the call to mainLoop.

This is a neat simulation that showcases the basics of particle physics in a confined space with simple elastic collisions.