vr-space-station/Assets/Scripts/Utility/MeshHelper.cs

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

namespace Utility.Meshes
{

    public static class Subdivion
    {
        static List<Vector3> vertices;
        static List<Vector3> normals;
        static List<Color> colors;
        static List<Vector2> uv;
        static List<Vector2> uv1;
        static List<Vector2> uv2;

        static List<List<int>> allIndices;
        static Dictionary<uint, int> newVectices;

        static void InitArrays(Mesh mesh)
        {
            vertices = new List<Vector3>(mesh.vertices);
            normals = new List<Vector3>(mesh.normals);
            colors = new List<Color>(mesh.colors);
            uv = new List<Vector2>(mesh.uv);
            uv1 = new List<Vector2>(mesh.uv2);
            uv2 = new List<Vector2>(mesh.uv2);
            allIndices = new List<List<int>>();
        }
        static void CleanUp()
        {
            vertices = null;
            normals = null;
            colors = null;
            uv = null;
            uv1 = null;
            uv2 = null;
            allIndices = null;
        }

        #region Subdivide4 (2x2)
        static int GetNewVertex4(int i1, int i2)
        {
            int newIndex = vertices.Count;
            uint t1 = ((uint)i1 << 16) | (uint)i2;
            uint t2 = ((uint)i2 << 16) | (uint)i1;
            if (newVectices.ContainsKey(t2))
                return newVectices[t2];
            if (newVectices.ContainsKey(t1))
                return newVectices[t1];

            newVectices.Add(t1, newIndex);

            vertices.Add((vertices[i1] + vertices[i2]) * 0.5f);
            if (normals.Count > 0)
                normals.Add((normals[i1] + normals[i2]).normalized);
            if (colors.Count > 0)
                colors.Add((colors[i1] + colors[i2]) * 0.5f);
            if (uv.Count > 0)
                uv.Add((uv[i1] + uv[i2]) * 0.5f);
            if (uv1.Count > 0)
                uv1.Add((uv1[i1] + uv1[i2]) * 0.5f);
            if (uv2.Count > 0)
                uv2.Add((uv2[i1] + uv2[i2]) * 0.5f);

            return newIndex;
        }


        /// <summary>
        /// Devides each triangles into 4. A quad(2 tris) will be splitted into 2x2 quads( 8 tris )
        /// </summary>
        /// <param name="mesh"></param>
        public static void Subdivide4(Mesh mesh)
        {
            newVectices = new Dictionary<uint, int>();

            InitArrays(mesh);

            int[] triangles = mesh.triangles;

            Debug.Log(mesh.subMeshCount);
            for (int j = 0; j < mesh.subMeshCount; j++)
            {
                var subMesh = mesh.GetSubMesh(j);

                allIndices.Add(new List<int>());
                List<int> subIndices = allIndices[j];

                for (int i = subMesh.indexStart; i < subMesh.indexStart + subMesh.indexCount; i += 3)
                {
                    int i1 = triangles[i + 0];
                    int i2 = triangles[i + 1];
                    int i3 = triangles[i + 2];

                    int a = GetNewVertex4(i1, i2);
                    int b = GetNewVertex4(i2, i3);
                    int c = GetNewVertex4(i3, i1);
                    subIndices.Add(i1); subIndices.Add(a); subIndices.Add(c);
                    subIndices.Add(i2); subIndices.Add(b); subIndices.Add(a);
                    subIndices.Add(i3); subIndices.Add(c); subIndices.Add(b);
                    subIndices.Add(a); subIndices.Add(b); subIndices.Add(c); // center triangle
                }
            }

            mesh.vertices = vertices.ToArray();

            if (normals.Count > 0)
                mesh.normals = normals.ToArray();
            if (colors.Count > 0)
                mesh.colors = colors.ToArray();
            if (uv.Count > 0)
                mesh.uv = uv.ToArray();
            if (uv1.Count > 0)
                mesh.uv2 = uv1.ToArray();
            if (uv2.Count > 0)
                mesh.uv2 = uv2.ToArray();


            mesh.triangles = allIndices.SelectMany(x => x).ToArray();
            mesh.subMeshCount = allIndices.Count;
            for (int i = 0; i < allIndices.Count; i++)
                mesh.SetTriangles(allIndices[i], i);


            CleanUp();
        }
        #endregion Subdivide4 (2x2)

        #region Subdivide9 (3x3)
        static int GetNewVertex9(int i1, int i2, int i3)
        {
            int newIndex = vertices.Count;

            // center points don't go into the edge list
            if (i3 == i1 || i3 == i2)
            {
                uint t1 = ((uint)i1 << 16) | (uint)i2;
                if (newVectices.ContainsKey(t1))
                    return newVectices[t1];
                newVectices.Add(t1, newIndex);
            }

            // calculate new vertex
            vertices.Add((vertices[i1] + vertices[i2] + vertices[i3]) / 3.0f);
            if (normals.Count > 0)
                normals.Add((normals[i1] + normals[i2] + normals[i3]).normalized);
            if (colors.Count > 0)
                colors.Add((colors[i1] + colors[i2] + colors[i3]) / 3.0f);
            if (uv.Count > 0)
                uv.Add((uv[i1] + uv[i2] + uv[i3]) / 3.0f);
            if (uv1.Count > 0)
                uv1.Add((uv1[i1] + uv1[i2] + uv1[i3]) / 3.0f);
            if (uv2.Count > 0)
                uv2.Add((uv2[i1] + uv2[i2] + uv2[i3]) / 3.0f);
            return newIndex;
        }


        /// <summary>
        /// Devides each triangles into 9. A quad(2 tris) will be splitted into 3x3 quads( 18 tris )
        /// </summary>
        /// <param name="mesh"></param>
        public static void Subdivide9(Mesh mesh)
        {
            newVectices = new Dictionary<uint, int>();

            InitArrays(mesh);

            int[] triangles = mesh.triangles;

            Debug.Log(mesh.subMeshCount);
            for (int j = 0; j < mesh.subMeshCount; j++)
            {
                var subMesh = mesh.GetSubMesh(j);

                allIndices.Add(new List<int>());
                List<int> subIndices = allIndices[j];
                for (int i = subMesh.indexStart; i < subMesh.indexStart + subMesh.indexCount; i += 3)
                {
                    int i1 = triangles[i + 0];
                    int i2 = triangles[i + 1];
                    int i3 = triangles[i + 2];

                    int a1 = GetNewVertex9(i1, i2, i1);
                    int a2 = GetNewVertex9(i2, i1, i2);
                    int b1 = GetNewVertex9(i2, i3, i2);
                    int b2 = GetNewVertex9(i3, i2, i3);
                    int c1 = GetNewVertex9(i3, i1, i3);
                    int c2 = GetNewVertex9(i1, i3, i1);

                    int d = GetNewVertex9(i1, i2, i3);

                    subIndices.Add(i1); subIndices.Add(a1); subIndices.Add(c2);
                    subIndices.Add(i2); subIndices.Add(b1); subIndices.Add(a2);
                    subIndices.Add(i3); subIndices.Add(c1); subIndices.Add(b2);
                    subIndices.Add(d); subIndices.Add(a1); subIndices.Add(a2);
                    subIndices.Add(d); subIndices.Add(b1); subIndices.Add(b2);
                    subIndices.Add(d); subIndices.Add(c1); subIndices.Add(c2);
                    subIndices.Add(d); subIndices.Add(c2); subIndices.Add(a1);
                    subIndices.Add(d); subIndices.Add(a2); subIndices.Add(b1);
                    subIndices.Add(d); subIndices.Add(b2); subIndices.Add(c1);
                }
            }

            mesh.vertices = vertices.ToArray();
            if (normals.Count > 0)
                mesh.normals = normals.ToArray();
            if (colors.Count > 0)
                mesh.colors = colors.ToArray();
            if (uv.Count > 0)
                mesh.uv = uv.ToArray();
            if (uv1.Count > 0)
                mesh.uv2 = uv1.ToArray();
            if (uv2.Count > 0)
                mesh.uv2 = uv2.ToArray();

            mesh.triangles = allIndices.SelectMany(x => x).ToArray();
            mesh.subMeshCount = allIndices.Count;
            for (int i = 0; i < allIndices.Count; i++)
                mesh.SetTriangles(allIndices[i], i);

            CleanUp();
        }
        #endregion Subdivide9 (3x3)


        #region Subdivide
        /// <summary>
        /// This functions subdivides the mesh based on the level parameter
        /// Note that only the 4 and 9 subdivides are supported so only those divides
        /// are possible. [2,3,4,6,8,9,12,16,18,24,27,32,36,48,64, ...]
        /// The function tried to approximate the desired level 
        /// </summary>
        /// <param name="mesh"></param>
        /// <param name="level">Should be a number made up of (2^x * 3^y)
        /// [2,3,4,6,8,9,12,16,18,24,27,32,36,48,64, ...]
        /// </param>
        public static void Subdivide(Mesh mesh, int level)
        {
            if (level < 2)
                return;
            while (level > 1)
            {
                // remove prime factor 3
                while (level % 3 == 0)
                {
                    Subdivide9(mesh);
                    level /= 3;
                }
                // remove prime factor 2
                while (level % 2 == 0)
                {
                    Subdivide4(mesh);
                    level /= 2;
                }
                // try to approximate. All other primes are increased by one
                // so they can be processed
                if (level > 3)
                    level++;
            }
        }
        #endregion Subdivide

        public static Mesh DuplicateMesh(Mesh mesh)
        {
            Mesh newMesh = (Mesh)UnityEngine.Object.Instantiate(mesh);

            newMesh.uv = mesh.uv;

            return newMesh;
        }
    }
}