Script to break mesh into smaller pieces?

Questions & Answers
1

Hi,

I looked at assets such as Unity Asset Store - The Best Assets for Game Making but they are quite expensive, I would like to ask if there is a free or cheaper alternative to be able to spit a mesh into many small pieces/rigidbodies?
Any advise would be appreciated.

2

Here is a script that will create seperate triangle rigidbodies from the gameObject’s mesh and make them explode, for a nice shattering effect. Works great for low-poly object, but might lead to performancy issues with medium-to high poly count objects. I think I found it on the unity wiki.

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


public class TriangleExplosion : MonoBehaviour {

	public IEnumerator SplitMesh (bool destroy)	{

		if(GetComponent<MeshFilter>() == null || GetComponent<SkinnedMeshRenderer>() == null) {
			yield return null;
		}

		if(GetComponent<Collider>()) {
			GetComponent<Collider>().enabled = false;
		}

		Mesh M = new Mesh();
		if(GetComponent<MeshFilter>()) {
			M = GetComponent<MeshFilter>().mesh;
		}
		else if(GetComponent<SkinnedMeshRenderer>()) {
			M = GetComponent<SkinnedMeshRenderer>().sharedMesh;
		}

		Material[] materials = new Material[0];
		if(GetComponent<MeshRenderer>()) {
			materials = GetComponent<MeshRenderer>().materials;
		}
		else if(GetComponent<SkinnedMeshRenderer>()) {
			materials = GetComponent<SkinnedMeshRenderer>().materials;
		}

		Vector3[] verts = M.vertices;
		Vector3[] normals = M.normals;
		Vector2[] uvs = M.uv;
		for (int submesh = 0; submesh < M.subMeshCount; submesh++) {

			int[] indices = M.GetTriangles(submesh);

			for (int i = 0; i < indices.Length; i += 3)	{
				Vector3[] newVerts = new Vector3[3];
				Vector3[] newNormals = new Vector3[3];
				Vector2[] newUvs = new Vector2[3];
				for (int n = 0; n < 3; n++)	{
					int index = indices[i + n];
					newVerts[n] = verts[index];
					newUvs[n] = uvs[index];
					newNormals[n] = normals[index];
				}

				Mesh mesh = new Mesh();
				mesh.vertices = newVerts;
				mesh.normals = newNormals;
				mesh.uv = newUvs;
				
				mesh.triangles = new int[] { 0, 1, 2, 2, 1, 0 };

				GameObject GO = new GameObject("Triangle " + (i / 3));
				GO.layer = LayerMask.NameToLayer("Particle");
				GO.transform.position = transform.position;
				GO.transform.rotation = transform.rotation;
				GO.AddComponent<MeshRenderer>().material = materials[submesh];
				GO.AddComponent<MeshFilter>().mesh = mesh;
				GO.AddComponent<BoxCollider>();
				Vector3 explosionPos = new Vector3(transform.position.x + Random.Range(-0.5f, 0.5f), transform.position.y + Random.Range(0f, 0.5f), transform.position.z + Random.Range(-0.5f, 0.5f));
				GO.AddComponent<Rigidbody>().AddExplosionForce(Random.Range(300,500), explosionPos, 5);
				Destroy(GO, 5 + Random.Range(0.0f, 5.0f));
			}
		}

		GetComponent<Renderer>().enabled = false;
		
		yield return new WaitForSeconds(1.0f);
		if(destroy == true) {
			Destroy(gameObject);
		}

	}


}

You can use it like this:

gameObject.AddComponent<TriangleExplosion>();

StartCoroutine(gameObject.GetComponent<TriangleExplosion().SplitMesh(true));