Editing Offset of Texture of Multi-Material Object

Question

I need to change the offset of the Bumpmap every Frame. The object has 6 materials with assigned normalmaps.

I always get this message: "NullReferenceException: Object reference not set to an instance of an object".

I do not know how to access the instance of the material.

 using UnityEngine;
 using System.Collections;
 
 public class offset : MonoBehaviour 
 {
     public float scrollSpeed = 0.01f;
     private Material[] mat = new Material[5];
 
     void Update () 
     {
         float offset = Time.time * scrollSpeed;
         mat[0].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
         mat[1].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
         mat[2].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
         mat[3].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
         mat[4].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
         mat[5].SetTextureOffset("_BumpMap", new Vector2(0f, offset));
     }
 }

Answer 1

Answer by rutter · Jan 23, 2014 at 12:00 AM

Materials are usually owned by Renderer components. You're getting a null reference because you've declared an array of materials, but didn't actually populate it with references to materials. Until you tell Unity otherwise, the array will be a bunch of nulls.

Assuming that Offset will be attached to a GameObject with exactly one renderer, you could access its materials like so:

 public class Offset : MonoBehaviour 
 {
     public float scroolSpeed = 0.01f;
     private Material[] mat;

     void Start() {
         mat = renderer.materials;
     }

     void Update() {
         float offset = Time.time * scrollSpeed;
         for (int i=0; i<mat.Length; i++) {
             mat[i].SetTextureOffset("_BumpMap", Vector2.up * offset);
         }
     }
 }

Editing Offset of Texture of Multi-Material Object

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