Passing MaterialPropertyBlock from one object to another

Hi everyone,

I have an issue that I can't figure out:

First, I don't know if it's of any importance, but I'm using the Universal Render Pipeline.

I have 4 player GameObjects (named "Playern") which have the same material ("PlayerMat"). Each player has a proper MaterialPropertyBlock that sets its color to be specific.

When a player shoots, I instantiate a "Ammo" GameObject, which I want to have the same color as the player. Thus, I want to access the player's MaterialPropertyBlock through the newly instantiated ammo.

I created a SetColor method attached to the ammo prefab:

Code (CSharp):

1. public class AmmoColor : MonoBehaviour
2. {
3.     private Renderer ammoRenderer;
4.  
5.     void Start()
6.     {
7.         ammoRenderer = gameObject.GetComponent<Renderer>();
8.     }
9.  
10.     public void SetColor(MaterialPropertyBlock playerBlock)
11.     {
12.         ammoRenderer.SetPropertyBlock(playerBlock);
13.     }
14. }

that is called by the Player after instantiating the ammo:

Code (CSharp):

1. GameObject ammoFired = Instantiate(ammo, transform.position, transform.rotation);
2. ammoFired.GetComponent<AmmoColor>().SetColor(playerBlock);

The thing is that when doing so, I have a NullReferenceException:

"NullReferenceException: Object reference not set to an instance of an object
AmmoColor.SetColor (UnityEngine.MaterialPropertyBlock playerBlock) (at Assets/Scripts/AmmoColor.cs:19)"

I tried to Debug.Log(playerBlock.isEmpty) inside the SetColor method, which returns false, implying the method receives the MaterialPropertyBlock.

I went even further and tried the following:

Code (CSharp):

1. public void SetAmmoColor(MaterialPropertyBlock playerBlock)
2.     {
3.         Color playerColor = playerBlock.GetColor("_BaseColor");
4.         Debug.Log(playerColor);
5.  
6.         ammoBlock.SetColor("_BaseColor", playerColor);
7.         ammoRenderer.SetPropertyBlock(ammoBlock);
8.     }

The Debug efficiently displays the right color (that of the player), but the exact same NullReferenceException points at the 6th line (

ammoBlock.SetColor("_BaseColor", playerColor);

), even though there is no reference to playerBlock.

Does anyone have an idea of what I'm doing wrong?

Thanks!

EDIT: it seems to work if I put the 6th and 7th lines in the Update method instead of the SetAmmoColor method. I really don't know nor understand why. The thing is I don't need to update the material color each frame. I might still look forward to resolving this.

 

Hi Shaunyowns,

Yes it works, but since the color change isn't made directly, there still is a single frame where the ammo instance isn't coloured, just before the Update call.

I'm using the 2019.3.7f1 version.

Thanks for your attention!

 

I'm using version 7.3.1