code for drawing nice Gizmo Cylinders in Unity

CylinderGizmoDemo.cs

using System;
using UnityEngine;

public class CylinderGizmoDemo : MonoBehaviour
{
    public Color _color = Color.cyan;
    public float _radius = 0.5f;
    public float _height = 2f;
    public int _circlePoints = 16;
    public int _slices = 2;
    public int _upwardLines = 6;
    public bool _drawEndLines;

    private void OnDrawGizmos()
    {
        var pos = transform.position;
        var rot = transform.rotation;
        Gizmos.color = _color;
        
        // basic call
        DrawCylinderGizmo(pos, rot, _radius, _height, _circlePoints, _slices, _upwardLines, _drawEndLines);
        
        // simple call
        // DrawCylinderGizmo(pos, rot, _radius*2, _height*2);

        // even simpler call
        // DrawCylinderGizmo(_radius, _height);
    }

    private void DrawCylinderGizmo(float radius, float height)
    {
        var pos = transform.position;
        var rot = transform.rotation;
        ;
        DrawCylinderGizmo(pos, rot, radius, height);
    }

    private void DrawCylinderGizmo(Vector3 position, Quaternion rotation, float radius, float height,
        int circlePoints = 24, int horizontalSlices = 1, int upwardLines = 6, bool drawEndLines = false)
    {
        // sanitise the input values silently
        radius = Mathf.Clamp(radius, 0.01f, 100f);
        height = Mathf.Clamp(height, 0.01f, 100f);
        circlePoints = Mathf.Clamp(circlePoints, 3, 48);
        upwardLines = Mathf.Clamp(upwardLines, 1, 48);
        horizontalSlices = Mathf.Clamp(horizontalSlices, 0, 48);

        // set position etc
        Gizmos.matrix = Matrix4x4.TRS(position, rotation, Vector3.one);

        Vector3[] topCirclePoints = new Vector3[circlePoints];
        Vector3[] bottomCirclePoints = new Vector3[circlePoints];

        for (int i = 0; i < circlePoints; i++)
        {
            float angle = (2 * Mathf.PI / circlePoints) * i;
            float x = radius * Mathf.Cos(angle);
            float z = radius * Mathf.Sin(angle);

            topCirclePoints[i] = new Vector3(x, height, z);
            bottomCirclePoints[i] = new Vector3(x, 0, z);
        }

        // draw slices
        if (horizontalSlices > 0)
        {
            float sliceHeightStep = height / (horizontalSlices + 1);
            for (int i = 1; i <= horizontalSlices; i++)
            {
                float sliceHeight = sliceHeightStep * i;
                for (int j = 0; j < circlePoints; j++)
                {
                    Vector3 poleStart = new Vector3(bottomCirclePoints[j].x, sliceHeight, bottomCirclePoints[j].z);
                    Vector3 poleEnd = j < circlePoints - 1
                        ? new Vector3(bottomCirclePoints[j + 1].x, sliceHeight, bottomCirclePoints[j + 1].z)
                        : new Vector3(bottomCirclePoints[0].x, sliceHeight, bottomCirclePoints[0].z);

                    Gizmos.DrawLine(poleStart, poleEnd);
                }
            }
        }

        upwardLines = Math.Min(circlePoints, upwardLines);

        if (upwardLines > 0)
        {
            int upwardLineStep = circlePoints / upwardLines;
            for (int i = 0; i < circlePoints; i++)
            {
                if (i % upwardLineStep == 0)
                {
                    Gizmos.DrawLine(bottomCirclePoints[i], topCirclePoints[i]);

                    // Draw a line from the circle center to the edge of each vertical pole
                    if (drawEndLines)
                    {
                        Gizmos.DrawLine(Vector3.zero, bottomCirclePoints[i]);
                        Gizmos.DrawLine(Vector3.up * height, topCirclePoints[i]);
                    }
                }

                if (i < circlePoints - 1)
                {
                    Gizmos.DrawLine(bottomCirclePoints[i], bottomCirclePoints[i + 1]);
                    Gizmos.DrawLine(topCirclePoints[i], topCirclePoints[i + 1]);
                }
                else
                {
                    Gizmos.DrawLine(bottomCirclePoints[i], bottomCirclePoints[0]);
                    Gizmos.DrawLine(topCirclePoints[i], topCirclePoints[0]);
                }
            }
        }

        Gizmos.matrix = Matrix4x4.identity;
    }
}

some code to make nice looking cylinders