itch.io

I don't know if I feel comfortable putting the whole project on github publicly. But the line drawing is actually quite simple. 

Both the trajectory line and the circle around the player are just made using the built-in Unity line renderer.

This is the Circle Drawer Script for example (hopefully more readable if you paste it into your ide):

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(LineRenderer))]
public class CircleDrawer : MonoBehaviour
{
private struct CircleProperties
{
public float Radius;
public float LineWidth;
public CircleProperties(float radius, float lineWidth)
{
Radius = radius;
LineWidth = lineWidth;
}
}

[SerializeField]
private int _resolution = 20;
[SerializeField]
private float _lerpSpeed = 3f;

private LineRenderer _lineRenderer = null;
private CircleProperties _currentCircle = new CircleProperties(1f, 0.5f); 
private CircleProperties _targetCircle = new CircleProperties(1f, 0.5f);

private Transform _transform = null;
private Transform _followTarget = null;
private Vector3 _followOffset = Vector3.zero;

private void Awake()
{
_transform = transform;
_lineRenderer = GetComponent<LineRenderer>();
_lineRenderer.enabled = false;
}

private void Update()
{
if (_followTarget)
{
transform.position = _followTarget.position + _followOffset + Vector3.up * (_currentCircle.LineWidth/2f);
}

if (_lineRenderer.enabled)
{
if (_lineRenderer.positionCount != _resolution)
_lineRenderer.positionCount = _resolution;

float anglePerCount = 360f / ((float)_resolution);
for (int i = 0; i < _resolution; i++)
{
float currentAngle = anglePerCount * (float)i;
currentAngle *= Mathf.Deg2Rad;

Vector3 unitVector = new Vector3(Mathf.Cos(currentAngle), 0f, Mathf.Sin(currentAngle));
_lineRenderer.SetPosition(i, _transform.position + (unitVector * _currentCircle.Radius));
}

_lineRenderer.widthMultiplier = _currentCircle.LineWidth;

CircleProperties updatedCircle = _currentCircle;
updatedCircle.Radius = Mathf.Lerp(_currentCircle.Radius, _targetCircle.Radius, _lerpSpeed * Time.unscaledDeltaTime);
updatedCircle.LineWidth = Mathf.Lerp(_currentCircle.LineWidth, _targetCircle.LineWidth, _lerpSpeed * Time.unscaledDeltaTime);

_currentCircle = updatedCircle;
}
}

public void SetFollowTarget(Transform target, Vector3 offset)
{
_followTarget = target;
_followOffset = offset;
}

public void TurnOff()
{
_lineRenderer.enabled = false;
_targetCircle = new CircleProperties(1f, 0.5f);
}

public void SetCircle(float radius, float lineWidth)
{
_lineRenderer.enabled = true;
_targetCircle = new CircleProperties(radius, lineWidth);
}
}