initial

Author: arhcy

MeshSlicerForCulling.cs

@@ -0,0 +1,282 @@
+// Copyright (c) 2018 Archy Piragkov. All Rights Reserved.  Licensed under the MIT license
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using System.Linq;
+
+
+namespace Artics.EditorUtils
+{
+    #region Slicer
+    /// <summary>
+    /// Slices big meshes into smaller parts to get better performance with occlusion culling.
+    ///
+    /// I wrote this component for my project and I think it can be useful for your projects too :) Currently, it supports only slicing by X and Y axes. It's don't separates triangles if they are in different parts, so use it only for high poly meshes Maybe I'll improve in the future.
+
+    /// Using is simple.
+    /// 1. Drag here gameobject which contains MeshFilter object of mesh which you want to slice.
+    /// 2. Set a default material for new parts
+    /// 3. Set number of parts by vertical and horizontal
+    /// 4. Press thew "Slice bounded" button
+    ///
+    ///You can also use second methotd, but it's rather a crutch. I just wrote it for the test and decided to left him.
+    ///
+    ///To test bounds of any mesh - drag it gameobject to BoundsVisualizer and press visualize bounds.
+    /// </summary>
+    public class MeshSlicerForCulling : MonoBehaviour
+    {
+        #region Variables
+
+        public GameObject Container;
+        public Material DefaultMaterial;
+
+        public int Parts;
+        public int Limit;
+
+        public GameObject BoundsVisualizer;
+
+        protected Bounds[] Bounds;
+        protected Bounds VisualizeBounds;
+
+        #endregion
+
+        #region BoundsMethod         
+
+        [NaughtyAttributes.Button("Slice bounded")]
+        public void SliceBounded()
+        {
+            transform.position = Container.transform.position;
+
+            GameObject newParent = new GameObject($"[Sliced] {Container.name}");
+            newParent.transform.position = Container.transform.position;
+            var baseMesh = Container.GetComponent<MeshFilter>().sharedMesh;
+
+            var meshCache = new MeshCache() { Instance = baseMesh, Vertices = baseMesh.vertices, Triangles = baseMesh.triangles, Normals = baseMesh.normals, UVs = baseMesh.uv };
+
+            //bounds  preparations
+            int boundsParts = Parts * Parts;
+            var boundsArr = new Bounds[boundsParts];
+
+            baseMesh.RecalculateBounds();
+            var meshBounds = baseMesh.bounds;
+
+            Vector3 size = meshBounds.size / Parts;
+            size.z = meshBounds.size.z;
+
+            //bounds calculations
+            for (int x = 0; x < Parts; x++)
+                for (int y = 0; y < Parts; y++)
+                    boundsArr[x * Parts + y] = new Bounds(meshBounds.min + new Vector3(size.x * x, size.y * y, 0) + size * 0.5f, size);
+
+            Bounds = boundsArr;
+
+            //triangle-bounds mask
+            var trianglesMask = new int[meshCache.Triangles.Length];
+
+            for (int i = 0; i < trianglesMask.Length; i++)
+                trianglesMask[i] = -1;
+
+            //creatig meshes
+            for (int i = 0; i < boundsParts; i++)
+            {
+                FindstrianglesInBounds(boundsArr[i], i, trianglesMask, meshCache);
+                CreateMeshFromBoundMask(i, trianglesMask, meshCache, newParent.transform);
+            }
+
+        }
+
+        public void FindstrianglesInBounds(Bounds bounds, int id, int[] trianglesMask, MeshCache cache)
+        {
+            for (int i = 0; i < trianglesMask.Length; i += 3)
+                if (trianglesMask[i] != -1 && bounds.Contains(cache.Vertices[cache.Triangles[i]]) || bounds.Contains(cache.Vertices[cache.Triangles[i + 1]]) || bounds.Contains(cache.Vertices[cache.Triangles[i + 2]]))
+                    trianglesMask[i] = trianglesMask[i + 1] = trianglesMask[i + 2] = id;
+        }
+
+
+        public void CreateMeshFromBoundMask(int id, int[] boundsMask, MeshCache cache, Transform parent = null)
+        {
+            var boundedTriangles = new List<int>();
+
+            for (int i = 0; i < boundsMask.Length; i++)
+                if (boundsMask[i] == id)
+                    boundedTriangles.Add(cache.Triangles[i]);
+
+            if (boundedTriangles.Count == 0)
+            {
+                Debug.LogWarning($"Sector:{id} - no triangles found");
+                return;
+            }
+
+            int TrianglesPartAmmount = boundedTriangles.Count;
+            var vertexesDictionary = new Dictionary<int, Vector3>();
+            var triangles = cache.Triangles;
+            var vertices = cache.Vertices;
+
+            for (int i = 0; i < TrianglesPartAmmount; i++)
+                vertexesDictionary[boundedTriangles[i]] = vertices[boundedTriangles[i]];
+
+            //new vertices
+            var newVertices = vertexesDictionary.Values.ToArray();
+
+            //new triangles
+            var keysList = vertexesDictionary.Keys.ToList();
+            var newTriangles = new int[TrianglesPartAmmount];
+
+            for (int i = 0; i < TrianglesPartAmmount; i++)
+                newTriangles[i] = keysList.IndexOf(boundedTriangles[i]);
+
+            int verticesPartAmmount = keysList.Count;
+            //uv
+            var oldUV = cache.UVs;
+            var newUV = new Vector2[verticesPartAmmount];
+
+            for (int i = 0; i < verticesPartAmmount; i++)
+                newUV[i] = oldUV[keysList[i]];
+
+            //normals
+            var oldNormals = cache.Normals;
+            var newNormals = new Vector3[verticesPartAmmount];
+
+            for (int i = 0; i < verticesPartAmmount; i++)
+                newNormals[i] = oldNormals[keysList[i]];
+
+            //creating GameObject
+
+            var child = new GameObject($"Sector {id}");
+            child.transform.parent = parent;
+            child.transform.localPosition = Vector3.zero;
+
+            var newMesh = new Mesh();
+            newMesh.vertices = newVertices;
+            newMesh.triangles = newTriangles;
+            newMesh.uv = newUV;
+            newMesh.normals = newNormals;
+
+            newMesh.RecalculateBounds();
+
+
+            child.AddComponent<MeshFilter>().mesh = newMesh;
+            child.AddComponent<MeshRenderer>().material = DefaultMaterial;
+        }
+
+        #endregion
+
+        #region PolygonMethod
+
+        [NaughtyAttributes.Button("Slice")]
+        public void SimpleSlice()
+        {
+            GameObject newParent = new GameObject();
+            newParent.transform.position = Container.transform.position;
+
+            var baseMesh = Container.GetComponent<MeshFilter>().sharedMesh;
+
+            int facesNum = baseMesh.triangles.Length / 3;
+            int partFacesAmmount = facesNum / Parts;
+            int TrianglesPartAmmount = partFacesAmmount * 3;
+
+            for (int i = 0; i < Parts - 1; i++)
+                CreateMeshFromRange(i * partFacesAmmount, (i + 1) * partFacesAmmount, baseMesh, newParent.transform);
+
+            CreateMeshFromRange(partFacesAmmount * (Parts - 1), facesNum, baseMesh, newParent.transform);
+        }
+
+        public void CreateMeshFromRange(int startTriangle, int endTriangle, Mesh baseMesh, Transform parent = null)
+        {
+            int trianglesPartAmmount = (endTriangle - startTriangle) * 3;
+            int startId = startTriangle * 3;
+            int endId = endTriangle * 3;
+            var vertexesDictionary = new Dictionary<int, Vector3>();
+            var triangles = baseMesh.triangles;
+            var vertices = baseMesh.vertices;
+
+            for (int i = startId; i < endId; i++)
+                vertexesDictionary[triangles[i]] = vertices[triangles[i]];
+
+            //new vertices
+            var newVertices = vertexesDictionary.Values.ToArray();
+
+            //new triangles
+            var keysList = vertexesDictionary.Keys.ToList();
+            var newTriangles = new int[trianglesPartAmmount];
+
+            for (int i = 0; i < trianglesPartAmmount; i++)
+                newTriangles[i] = keysList.IndexOf(triangles[startId + i]);
+
+            int verticesPartAmmount = keysList.Count;
+            //uv
+            var oldUV = baseMesh.uv;
+            var newUV = new Vector2[verticesPartAmmount];
+
+            for (int i = 0; i < verticesPartAmmount; i++)
+                newUV[i] = oldUV[keysList[i]];
+
+            //normals
+            var oldNormals = baseMesh.normals;
+            var newNormals = new Vector3[verticesPartAmmount];
+
+            for (int i = 0; i < verticesPartAmmount; i++)
+                newNormals[i] = oldNormals[keysList[i]];
+
+            //creating GameObject
+
+            var child = new GameObject();
+            child.transform.parent = parent;
+            child.transform.localPosition = Vector3.zero;
+
+            var newMesh = new Mesh();
+            newMesh.vertices = newVertices;
+            newMesh.triangles = newTriangles;
+            newMesh.uv = newUV;
+            newMesh.normals = newNormals;
+
+            newMesh.RecalculateBounds();
+
+            child.AddComponent<MeshFilter>().mesh = newMesh;
+            child.AddComponent<MeshRenderer>().material = DefaultMaterial;
+        }
+
+        #endregion
+
+        #region Visualizing
+
+        [NaughtyAttributes.Button("Visualize bounds")]
+        public void CalcBoundsVisualizer()
+        {
+            VisualizeBounds = BoundsVisualizer.GetComponent<MeshFilter>().sharedMesh.bounds;
+        }
+
+        private void OnDrawGizmos()
+        {
+            Vector3 pos = transform.position;
+
+            if (Bounds != null)
+                for (int i = 0; i < Bounds.Length; i++)
+                    if (i < Limit)
+                        Gizmos.DrawWireCube(Bounds[i].center + pos, Bounds[i].size);
+
+            if (BoundsVisualizer != null)
+            {
+                Gizmos.color = Color.red;
+                Gizmos.DrawWireCube(VisualizeBounds.center + BoundsVisualizer.transform.position, VisualizeBounds.size);
+            }
+        }
+
+        #endregion
+    }
+
+    #endregion
+
+    #region MeshCache
+
+    public class MeshCache
+    {
+        public Mesh Instance;
+        public int[] Triangles;
+        public Vector3[] Vertices;
+        public Vector2[] UVs;
+        public Vector3[] Normals;
+    }
+
+    #endregion
+}

README.md

@@ -1,2 +1,27 @@
 # Unity3d-mesh-slicer-for-culling
 Slices big meshes into smaller parts to get better performance with occlusion culling.
+ 
+ <p align="center">
+ <img align="center" width="60%" src="/images/scr2.png">
+ </p>
+
+I wrote this component for my project and I think it can be useful for your projects too :) Currently, it supports only slicing by X and Y axes. It's don't separates triangles if they are in different parts, so use it only for high poly meshes  Maybe I'll improve in the future.
+
+Using is simple.
+
+ <p align="center">
+ <img align="center" width="40%" src="/Screenshots/scr1.png">
+ </p>
+
+1. Drag here gameobject which contains MeshFilter object of mesh which you want to slice.
+
+2. Set a default material for new parts
+
+3. Set number of parts by vertical and horizontal
+
+4. Press this button
+
+
+You can also use second methotd, but it's rather a crutch. I just wrote it for the test and decided to left him.
+
+To test bounds of any mesh - drag it gameobject to BoundsVisualizer and press visualize bounds.