とりあえず、直角三角柱を作るエディタ拡張。これから形状を増やしていく予定。

CreateOtherPrimitive.cs

using UnityEngine;
using UnityEditor;
using System.Collections;

namespace TAKL
{
	public class CreateOtherPrimitive : EditorWindow
	{
		[MenuItem("GameObject/Create Other/Other Primitives/Half Cube")]
		public static GameObject CreateHalfCube()
		{
			GameObject hCube = new GameObject("HalfCube");

			MeshFilter mf = hCube.AddComponent<MeshFilter>();

			Vector3[] vert = new Vector3[8 * 3];
			vert[0] = new Vector3(-0.5f, 0.5f, -0.5f);
			vert[1] = new Vector3(-0.5f, 0.5f, 0.5f);
			vert[2] = new Vector3(0.5f, 0.5f, -0.5f);

			vert[3] = new Vector3(-0.5f, 0.5f, 0.5f);
			vert[4] = new Vector3(-0.5f, 0.5f, -0.5f);
			vert[5] = new Vector3(-0.5f, -0.5f, -0.5f);

			vert[6] = new Vector3(-0.5f, 0.5f, 0.5f);
			vert[7] = new Vector3(-0.5f, -0.5f, -0.5f);
			vert[8] = new Vector3(-0.5f, -0.5f, 0.5f);

			vert[9] = new Vector3(-0.5f, 0.5f, -0.5f);
			vert[10] = new Vector3(0.5f, 0.5f, -0.5f);
			vert[11] = new Vector3(-0.5f, -0.5f, -0.5f);

			vert[12] = new Vector3(0.5f, 0.5f, -0.5f);
			vert[13] = new Vector3(0.5f, -0.5f, -0.5f);
			vert[14] = new Vector3(-0.5f, -0.5f, -0.5f);

			vert[15] = new Vector3(0.5f, 0.5f, -0.5f);
			vert[16] = new Vector3(-0.5f, 0.5f, 0.5f);
			vert[17] = new Vector3(0.5f, -0.5f, -0.5f);

			vert[18] = new Vector3(-0.5f, 0.5f, 0.5f);
			vert[19] = new Vector3(-0.5f, -0.5f, 0.5f);
			vert[20] = new Vector3(0.5f, -0.5f, -0.5f);

			vert[21] = new Vector3(-0.5f, -0.5f, -0.5f);
			vert[22] = new Vector3(0.5f, -0.5f, -0.5f);
			vert[23] = new Vector3(-0.5f, -0.5f, 0.5f);

			Vector2[] uv = new Vector2[8 * 3];
			uv[0] = new Vector2(0.0f, 0.0f);
			uv[1] = new Vector2(0.0f, 1.0f);
			uv[2] = new Vector2(1.0f, 0.0f);

			uv[3] = new Vector2(0.0f, 1.0f);
			uv[4] = new Vector2(1.0f, 1.0f);
			uv[5] = new Vector2(1.0f, 0.0f);

			uv[6] = new Vector2(0.0f, 1.0f);
			uv[7] = new Vector2(1.0f, 0.0f);
			uv[8] = new Vector2(0.0f, 0.0f);

			uv[9] = new Vector2(0.0f, 1.0f);
			uv[10] = new Vector2(1.0f, 1.0f);
			uv[11] = new Vector2(0.0f, 0.0f);

			uv[12] = new Vector2(1.0f, 1.0f);
			uv[13] = new Vector2(1.0f, 0.0f);
			uv[14] = new Vector2(0.0f, 0.0f);

			uv[15] = new Vector2(0.0f, 1.0f);
			uv[16] = new Vector2(1.0f, 1.0f);
			uv[17] = new Vector2(0.0f, 0.0f);

			uv[18] = new Vector2(1.0f, 1.0f);
			uv[19] = new Vector2(1.0f, 0.0f);
			uv[20] = new Vector2(0.0f, 0.0f);

			uv[21] = new Vector2(1.0f, 0.0f);
			uv[22] = new Vector2(0.0f, 0.0f);
			uv[23] = new Vector2(1.0f, 1.0f);

			int[] ifs = new int[8 * 3];
			ifs[0] = 0;
			ifs[1] = 1;
			ifs[2] = 2;

			ifs[3] = 3;
			ifs[4] = 4;
			ifs[5] = 5;

			ifs[6] = 6;
			ifs[7] = 7;
			ifs[8] = 8;

			ifs[9] = 9;
			ifs[10] = 10;
			ifs[11] = 11;

			ifs[12] = 12;
			ifs[13] = 13;
			ifs[14] = 14;

			ifs[15] = 15;
			ifs[16] = 16;
			ifs[17] = 17;

			ifs[18] = 18;
			ifs[19] = 19;
			ifs[20] = 20;

			ifs[21] = 21;
			ifs[22] = 22;
			ifs[23] = 23;

			Mesh mesh = new Mesh();
			mesh.name = "HalfCube";
			mesh.vertices = vert;
			mesh.uv = uv;
			mesh.triangles = ifs;

			mesh.RecalculateBounds();
			mesh.RecalculateNormals();

			mf.sharedMesh = mesh;

			MeshCollider mc = hCube.AddComponent<MeshCollider>();
			mc.convex = true;

			MeshRenderer mr = hCube.AddComponent<MeshRenderer>();

			Material mat = new Material(Shader.Find("Diffuse"));
			mat.name = "Default-Diffuse";
			mat.color = Color.white;
			mr.renderer.sharedMaterial = mat;

			return hCube;
		}
	}
}