Changing material properties on one object changes all others

Question

I have a fadeout script to change the material properties when something blocks the screen. I want the objects to fade individually but when a new object fades, all the others also start the fade again or start fully faded out immediately.

The Docs say changing material properties using Renderer.material creates a new instance of the material, but the behaviour I see points to them still being the same instance.

The material is a simple unlit shadergraph and here's the Coroutine I use to fade the object:

 IEnumerator TransitionTransparency() {
     _renderer.material = _transparentMat;
 
     float transition = 1;
     while (transition > 0) {
         _renderer.material.SetFloat("_Transition", transition);
 
         transition -= Time.deltaTime / _transitionTime;
         yield return null;
     }
 
     Destroy(_renderer.material);
     _renderer.material = _transparentMat;
       
     yield break;
 }

Answer 1

I'd recommend Material Property Blocks. It is a class that you can set to almost every renderer and it will override the renderer's shader properties.

For Instance, here is a script that I wrote for tweaking the "_Fade" property using DOTween.

 using DG.Tweening;
 using UnityEngine;
 using UnityEngine.Events;
 
 public class Interactable : MonoBehaviour, IRaycastEnter
 {
     [SerializeField] protected MeshRenderer mR;
     protected MaterialPropertyBlock mPB;
     protected Vector3 StartScale;
 
     protected float tw = 0;
 
     protected virtual void Awake()
     {
         mPB = new MaterialPropertyBlock();
     }

      // This isn't the whole script but I think that would be enough to show how it works.
     public virtual void OnRaycastEnter()
     {
         if (!interactable) return;
 
         //throw new System.NotImplementedException();
         if (flashTW != null) flashTW.Kill();
         flashTW = DOTween.To(() => tw, x => tw = x, 1, .22f)
                 .OnUpdate(() =>
                 {
                     mR.transform.localScale = StartScale * (1 + (tw * scaleMultiplier));
                     // This is the Material Property Part, first you get the property block from the renderer.
                     mR.GetPropertyBlock(mPB);

                     //Then you tweak the values in the Material Property Block
                     mPB.SetFloat("_Fade", tw);

                     //Finally you set the property block of the renderer
                     mR.SetPropertyBlock(mPB);
                 });
     }
 }

Answer 2

Answer by consumedman · May 10 at 05:37 PM

So after trying out a few things I found the solution. Leaving it here for anyone having a similar issue in the future.

The problem is with how shadergraph shaders handles non-exposed properties by default. If you want to have a non-exposed property that can be changed for every material instance you have to enable "Override property declaration" and set "Shader Declaration" to "per material" in the property settings.

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Changing material properties on one object changes all others

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