NestedPreb

屌丝手动版

One of the things we’re sorely missing from Unity is nested prefabs. So we rolled this little script to help us out – and figured other people could benefit as well.

You just add this script to a gameobject, and point the prefab field at the prefab you want instantiated.

This will render the prefab in the scene view while editing, and at bake time it will copy the objects into the scene so your gamecode can just work. It doesn’t allow overriding properties, and only previews the meshes, but we’ve been able to use it a lot for building props: We have a Gameobject that contains all the logic for a prop (e.g. definitions of cover points for a crate) – and then uses this script to pull in the actual FBX file that has the graphics. Now our graphic artist can just modify that and everything works.

You can also reference other prefabs, and nest these PrefabInstance scripts. While not as cool as a real system, it pretty much has solved our use cases.

using UnityEngine;
#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.Callbacks;
#endif
using System.Collections.Generic;

[ExecuteInEditMode]
public class PrefabInstance : MonoBehaviour
{
    public GameObject prefab;

#if UNITY_EDITOR    
    // Struct of all components. Used for edit-time visualization and gizmo drawing
    public struct Thingy {
        public Mesh mesh;
        public Matrix4x4 matrix;
        public List<Material> materials;
    }

    [System.NonSerializedAttribute] public List<Thingy> things = new List<Thingy> ();

    void OnValidate () {
        things.Clear();
        if (enabled)
            Rebuild (prefab, Matrix4x4.identity);
    }

    void OnEnable () {
        things.Clear();
        if (enabled)
            Rebuild (prefab, Matrix4x4.identity);
    }

    void Rebuild (GameObject source, Matrix4x4 inMatrix) {
        if (!source)
            return;

        Matrix4x4 baseMat = inMatrix * Matrix4x4.TRS (-source.transform.position, Quaternion.identity, Vector3.one);
        
        foreach (MeshRenderer mr in source.GetComponentsInChildren(typeof (Renderer), true))
        {
            things.Add(new Thingy () {
                mesh = mr.GetComponent<MeshFilter>().sharedMesh,
                matrix = baseMat * mr.transform.localToWorldMatrix,
                materials = new List<Material> (mr.sharedMaterials)
            });
        }

        foreach (PrefabInstance pi in source.GetComponentsInChildren(typeof (PrefabInstance), true))
        {
            if (pi.enabled && pi.gameObject.activeSelf)
                Rebuild (pi.prefab, baseMat * pi.transform.localToWorldMatrix);
        }        
    }

    // Editor-time-only update: Draw the meshes so we can see the objects in the scene view
    void Update () {
        if (EditorApplication.isPlaying)
            return;
        Matrix4x4 mat = transform.localToWorldMatrix;
        foreach (Thingy t in things)
            for (int i = 0; i < t.materials.Count; i++)
                Graphics.DrawMesh (t.mesh, mat * t.matrix, t.materials[i], gameObject.layer, null, i);
    }

    // Picking logic: Since we don't have gizmos.drawmesh, draw a bounding cube around each thingy
    void OnDrawGizmos () { DrawGizmos (new Color (0,0,0,0)); }
    void OnDrawGizmosSelected () { DrawGizmos (new Color (0,0,1,.2f)); }
    void DrawGizmos (Color col) {
        if (EditorApplication.isPlaying)
            return;
        Gizmos.color = col;
        Matrix4x4 mat = transform.localToWorldMatrix;
        foreach (Thingy t in things)
        {
            Gizmos.matrix = mat * t.matrix;
            Gizmos.DrawCube(t.mesh.bounds.center, t.mesh.bounds.size);
        }        
    }

    // Baking stuff: Copy in all the referenced objects into the scene on play or build
    [PostProcessScene(-2)]
    public static void OnPostprocessScene() { 
        foreach (PrefabInstance pi in UnityEngine.Object.FindObjectsOfType (typeof (PrefabInstance)))
            BakeInstance (pi);
    }

    public static void BakeInstance (PrefabInstance pi) {
        if(!pi.prefab || !pi.enabled)
            return;
        pi.enabled = false;
        GameObject go = PrefabUtility.InstantiatePrefab(pi.prefab) as GameObject;
        Quaternion rot = go.transform.localRotation;
        Vector3 scale = go.transform.localScale;
        go.transform.parent = pi.transform;
        go.transform.localPosition = Vector3.zero;
        go.transform.localScale = scale;
        go.transform.localRotation = rot;
        pi.prefab = null;
        foreach (PrefabInstance childPi in go.GetComponentsInChildren<PrefabInstance>())
            BakeInstance (childPi);
    }

#endif
}

It uses the same principle as our IBakeable interface, but we want this to run before all the other IBakeable functions (so all objects are instantiated before we try to run others)

Real-Time Pixels

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