Fading out using render.material.color.a +=/-= doesn't work

Question

Hi,

I'm trying to fade out my object by reducing its alpha but it seems reluctent to accept this code;

renderer.material.color.a -= 0.1f;

The error message I get says the following;

"Error: Cannot modify the return value of 'UnityEngine.Material.color' because it is not a variable"

I do not see how this is not a variable I can modify. I vaguely remember using this code before though now I seem to be missing something.

EDIT IN RESPONSE TO ANSWER;

using UnityEngine; using System.Collections;

public class MyRenderer : MonoBehaviour {

 // Use this for initialization
 void Start () {

 }

 // Update is called once per frame
 void Update () {

     if (Input.GetMouseButtonUp(0))
     {
         Color color = renderer.material.color;
         color.a -= 0.1f;
         renderer.material.color = color;
     }
 }

}

This doesn't do anything when I attach it to a gameobject. Created a new gameobject, added the script, ran it, did nothing :( I'm using the latest version of unity btw. Thing is I didn't have this problem when using 2.6

Answer 1

Best Answer

Answer by Jessy · Apr 24, 2011 at 09:56 PM

Are you using an old version of Unity? The current version should tell you

Cannot modify a value type return value of `UnityEngine.Material.color'. Consider storing the value in a temporary variable

You just do what it says:

Color color = renderer.material.color;
color.a -= 0.1f;
renderer.material.color = color;

Adjusting just the alpha of the main color is a pretty common operation, so you may want to use this extension method until a better option is available. An extension property would be better, but those aren't in C# yet.

using UnityEngine;

public static class ExtensionMethods {

public static void SetAlpha (this Material material, float value) {
    Color color = material.color;
    color.a = value;
    material.color = color;
}

.

renderer.material.SetAlpha(renderer.material.color.a - .1F);

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Benny 1 · Apr 24, 2011 at 10:32 PM 0

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not working for me, I can see the value change in the inspector but nothing appears to be happening on screen, check the code i'm using, I edited my question

Jessy · Apr 24, 2011 at 10:35 PM 1

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If there aren't any errors, then you're just not using a shader that responds to changes in _Color's alpha value. Are you seeing the little white bar change in the material panel? Your code works fine for me.

Benny 1 · Apr 24, 2011 at 10:37 PM 0

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Yes that was the change I was referring to

Benny 1 · Apr 24, 2011 at 11:08 PM 0

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It's working now thank you :)

Zenov · May 17, 2015 at 06:21 AM 0

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just wanted to post an update: renderer is now deprecated http://docs.unity3d.com/ScriptReference/GameObject-renderer.html

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Answer 2

Answer by joe_bar · May 30, 2012 at 09:45 PM

This post is pretty old, but for those of you who might come across this problem. Make sure that your material shader is set to Transparent/Diffuse or some form of transparent material. Otherwise changing the alpha component does nothing.

An alternative to decrementing the alpha component :

 renderer.material.color -= new Color(0,0,0,.10f);

Though not super efficient its gets the job done. ,

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bustedkrutch · Aug 28, 2013 at 03:46 AM 0

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Thanks a bunch for this tip. I thought it was something like this but really didn't have enough experience to "know" what the real problem was.

Simon 9 · Sep 29, 2013 at 05:53 PM 0

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Great! This is exactly what I was missing.

awplays49 · May 17, 2015 at 09:48 PM 0

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What material can be completely opaque and completely transparent?

ajayajayaj awplays49 · Sep 10, 2016 at 06:41 PM 0

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You just need to set the rendering mode to transparent

Answer 3

Answer by jmasinteATI · Aug 13, 2015 at 08:10 PM

In Unity 5:

 Color color = GetComponent<Renderer>().material.color;
 color.a -= 0.1f;
 
 GetComponent<Renderer>().material.SetColor("_Color", color);

If you're using Standard Shader, make sure the Rendering Mode is set to transparent.

http://docs.unity3d.com/ScriptReference/Material.SetColor.html

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joshvamp · Dec 05, 2015 at 06:57 PM 0

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how can i set rendering mode ? I'm beginer and can work with sprites? please

jmasinteATI joshvamp · Dec 07, 2015 at 04:33 PM 0

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In the material component in the Inspector, beneath the name of the shader you're using, you'll see "Rendering mode" with a drop down box that displays the Rendering $$anonymous$$ode. By default, it's set to "Opaque." This is for the standard shader. Not all shaders have this drop down box.

Here is a screenshot: http://docs.unity3d.com/$$anonymous$$anual/StandardShader$$anonymous$$aterialParameterRendering$$anonymous$$ode.html

shenjiexiang1994 · May 29, 2018 at 10:07 AM 0

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That works! Thanks for this post

Answer 4

Answer by Kieran Chandler · Jun 17, 2012 at 07:43 PM

try this

 color.a = new Color(color.a - 0.1, color.r, color.g, color.b);

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Answer 5

 public static IEnumerator FadeOutThreeD (this Transform t, float targetAlpha, bool isVanish, float duration)
     {
         Renderer sr = t.GetComponent<Renderer> ();
         float diffAlpha = (targetAlpha - sr.material.color.a);
 
         float counter = 0;
         while (counter < duration) {
             float alphaAmount = sr.material.color.a + (Time.deltaTime * diffAlpha) / duration;
             sr.material.color = new Color (sr.material.color.r, sr.material.color.g, sr.material.color.b, alphaAmount);
 
             counter += Time.deltaTime;
             yield return null;
         }
         sr.material.color = new Color (sr.material.color.r, sr.material.color.g, sr.material.color.b, targetAlpha);
         if (isVanish) {
             sr.transform.gameObject.SetActive (false);
         }
     }






 using UnityEngine;
 using System.Collections;
 
 public class VanishObject : MonoBehaviour
 {
 
     void Start ()
     {
         
         StartCoroutine (transform.FadeOutThreeD (0, true, 10));
     }
 
 }

Fading out using render.material.color.a +=/-= doesn't work

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