open-project-1/UOP1_Project/Assets/Scripts/Effects/DustParticlesController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UOP1.StateMachine;

/// <summary>
/// Controls playback of particles connected to movement. Methods invoked by the StateMachine StateActions
/// </summary>
public class DustParticlesController : MonoBehaviour
{
	[SerializeField] ParticleSystem _walkingParticles = default;
	[SerializeField] ParticleSystem _landParticles = default;
	[SerializeField] ParticleSystem _jumpParticles = default;

	public void EnableWalkParticles()
	{
		_walkingParticles.Play();
	}

	public void DisableWalkParticles()
	{
		_walkingParticles.Stop();
	}

	public void PlayJumpParticles()
	{
		_jumpParticles.Play();
	}
	public void PlayLandParticles()
	{
		_landParticles.Play();
	}

	public void PlayLandParticles(float intensity)
	{
		// make sure intensity is always between 0 and 1
		intensity = Mathf.Clamp01(intensity);

		ParticleSystem.MainModule main = _landParticles.main;
		ParticleSystem.MinMaxCurve origCurve = main.startSize; //save original curve to be assigned back to particle system
		ParticleSystem.MinMaxCurve newCurve = main.startSize; //Make a new minMax curve and make our changes to the new copy

		float minSize = newCurve.constantMin;
		float maxSize = newCurve.constantMax;

		// use the intensity to change the maximum size of the particle curve
		newCurve.constantMax = Mathf.Lerp(minSize, maxSize, intensity);
		main.startSize = newCurve;

		_landParticles.Play();

		// Put the original startSize back where you found it
		StartCoroutine(ResetMinMaxCurve(_landParticles, origCurve));

		// Note: We don't necessarily need to reset the curve, as it will be overridden
	}

	private IEnumerator ResetMinMaxCurve(ParticleSystem ps, ParticleSystem.MinMaxCurve curve)
	{
		while (ps.isEmitting)
		{
			yield return null;
		}

		ParticleSystem.MainModule main = ps.main;
		main.startSize = curve;
	}
}