Script to create a hemisphere mesh

MakeSphereHemisphere.cs

// https://forum.unity.com/threads/script-to-create-a-hemisphere-mesh.496720/
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MakeSphereHemisphere : MonoBehaviour
{

	[Header("Sphere Options")]
	public float radius = 1f;
	[Range(1, 3)]
	public int meshSmoothness = 1;
	[Space]
	[Header("Hemisphere Options")]
	[Tooltip("Create north hemisphere only")]
	public bool hemisphere = false;
	[Tooltip("UV covers full sphere")]
	public bool fullUvRange = true;

	// Use this for initialization
	void Start()
	{
		MeshFilter mf = GetComponent<MeshFilter>();
		Make(mf);
		FlipNormals(mf);
	}


	void Make(MeshFilter mf)
	{
		Mesh mesh = mf.mesh;
		mesh.Clear();


		// Longitude |||
		int nbLong = 24 * meshSmoothness;
		// Latitude ---
		int nbLat = 16 * meshSmoothness;

		#region Vertices
		Vector3[] vertices = new Vector3[(nbLong + 1) * ((hemisphere) ? nbLat / 2 : nbLat) + 2];
		float _pi = Mathf.PI;
		float _2pi = _pi * 2f;

		vertices[0] = Vector3.up * radius;
		//for (int lat = 0; lat < nbLat; lat++)
		for (int lat = 0; lat < ((hemisphere) ? nbLat / 2 : nbLat); lat++)
		{
			float a1 = _pi * (float)(lat + 1) / (nbLat + 1);
			float sin1 = Mathf.Sin(a1);
			float cos1 = Mathf.Cos(a1);

			for (int lon = 0; lon <= nbLong; lon++)
			{
				float a2 = _2pi * (float)(lon == nbLong ? 0 : lon) / nbLong;
				float sin2 = Mathf.Sin(a2);
				float cos2 = Mathf.Cos(a2);

				vertices[lon + lat * (nbLong + 1) + 1] = new Vector3(sin1 * cos2, cos1, sin1 * sin2) * radius;
			}
		}
		vertices[vertices.Length - 1] = Vector3.up * -radius;
		#endregion

		#region Normals		
		Vector3[] normals = new Vector3[vertices.Length];
		for (int n = 0; n < vertices.Length; n++)
			normals[n] = vertices[n].normalized;
		#endregion

		#region UVs
		Vector2[] uvs = new Vector2[vertices.Length];
		uvs[0] = Vector2.up;
		uvs[uvs.Length - 1] = Vector2.zero;
		//for (int lat = 0; lat < nbLat; lat++)
		for (int lat = 0; lat < ((hemisphere) ? nbLat / 2 : nbLat); lat++)
			for (int lon = 0; lon <= nbLong; lon++)
			{
				//uvs[lon + lat * (nbLong + 1) + 1] = new Vector2((float)lon / nbLong, 1f - (float)(lat + 1) / (nbLat + 1));
				if (!hemisphere || fullUvRange) uvs[lon + lat * (nbLong + 1) + 1] = new Vector2((float)lon / nbLong, 1f - (float)(lat + 1) / (nbLat + 1));
				else uvs[lon + lat * (nbLong + 1) + 1] = new Vector2((float)lon / nbLong, 1f - (float)(lat + 1) / (nbLat / 2));
			}
		#endregion

		#region Triangles
		int nbFaces = vertices.Length;
		int nbTriangles = nbFaces * 2;
		int nbIndexes = nbTriangles * 3;
		int[] triangles = new int[nbIndexes];

		//Top Cap
		int i = 0;
		for (int lon = 0; lon < nbLong; lon++)
		{
			triangles[i++] = lon + 2;
			triangles[i++] = lon + 1;
			triangles[i++] = 0;
		}

		//Middle
		for (int lat = 0; lat < ((hemisphere) ? nbLat / 2 : nbLat) - 1; lat++)
		{
			for (int lon = 0; lon < nbLong; lon++)
			{
				int current = lon + lat * (nbLong + 1) + 1;
				int next = current + nbLong + 1;

				triangles[i++] = current;
				triangles[i++] = current + 1;
				triangles[i++] = next + 1;

				triangles[i++] = current;
				triangles[i++] = next + 1;
				triangles[i++] = next;
			}
		}


		if (!hemisphere)
		{
			//Bottom Cap
			for (int lon = 0; lon < nbLong; lon++)
			{
				triangles[i++] = vertices.Length - 1;
				triangles[i++] = vertices.Length - (lon + 2) - 1;
				triangles[i++] = vertices.Length - (lon + 1) - 1;
			}
		}
		#endregion

		mesh.vertices = vertices;
		mesh.normals = normals;
		mesh.uv = uvs;
		mesh.triangles = triangles;

		mesh.RecalculateBounds();
	}

	void FlipNormals (MeshFilter filter)
	{
		if (filter != null)
		{
			Mesh mesh = filter.mesh;

			Vector3[] normals = mesh.normals;
			for (int i = 0; i < normals.Length; i++)
				normals[i] = -normals[i];
			mesh.normals = normals;

			for (int m = 0; m < mesh.subMeshCount; m++)
			{
				int[] triangles = mesh.GetTriangles(m);
				for (int i = 0; i < triangles.Length; i += 3)
				{
					int temp = triangles[i + 0];
					triangles[i + 0] = triangles[i + 1];
					triangles[i + 1] = temp;
				}
				mesh.SetTriangles(triangles, m);
			}
		}
	}
}