Graphics.blit() not working for android!!

Hii everyone,

I have a query regarding Graphics.Blit() call for android. Here are the brief of the process:-
We are using Graphics.Blit(Texture source, RenderTexture dest, Material mat) to copy data from source texture to destination texture with a shader. This call is working in editor mode & for windows platform. But, in android platform, we don't see any content in destination texture.
We are making this call in Update() call.
Any suggestions to make it work in android platform? Any feedback regarding this will be helpful.

 

No errors are seen in logcat.
To verify if the problem is with Render Texture I have created, I used Blit(Texture source, RenderTexture dest). With this call, I can confirm that content getting copied to dest.
To verify if the problem is with the shader in android platform, I attached the shader to a material of cube(3D object asset in unity). With this, I can confirm that shader is doing its work properly in android platform.
Problem is seen only when I use Blit(Texture source, RenderTexture dest, Material mat) to apply the shader while copying from source to destination texture & problem is only in android platform.

Material mat = null;
Shader alphaSet = null;
RenderTexture rt = null;
Texture tex = null;
Texture2D tex2D = null;
void Start()
{
Color32 testColor = new Color32(255, 0, 0, 255);

alphaSet = Shader.Find("AlphaShader");
if(alphaSet)
{
Debug.Log("Found Alpha Set Shader");
mat = new Material(alphaSet);
mat.shader = alphaSet;
}
else
{
Debug.LogError("Did not find Alpha Set Shader XXXXXXXXXX ");
}
tex2D = new Texture2D(Screen.width, Screen.height, TextureFormat.ARGB32, false);
tex2D.filterMode = FilterMode.Point;
Color32[] testColorArray = tex2D.GetPixels32();
tex2D.name = "sample_tex2d";

for (int i = 0; i < testColorArray.Length; i++)
{
testColorArray = testColor;
}

tex2D.SetPixels32(testColorArray);
tex2D.Apply();

tex = tex2D;

rt.filterMode = FilterMode.Point;
rt.anisoLevel = 0;
rt.antiAliasing = Mathf.Max(QualitySettings.antiAliasing, 1);
rt.Create();
}

void Update()
{
Graphics.Blit(tex, rt, mat);
}

 

Creating RenderTexture was the problem.
We were using

Code (CSharp):

1.  rt = new RenderTexture(200, 100, 24, RenderTextureFormat.ARGB32);

Changing it to

Code (CSharp):

1.  rt = new RenderTexture(200, 100, 0, RenderTextureFormat.ARGB32);

worked.

Not sure, how depth buffer size was affecting only in android platform. Any explanation?
Information you requested made me look at the parameters passed to Render Texture.
Thank you for the support.

 

I'm having a similar problem, Graphics.Blit giving me a black screen on an Android device but working fine in the Editor or on a Rift.
The case is even simpler.
I'm sure it is some kind of configuration error, I just can't figure out what.

Code (CSharp):

1.  
2. private void Start()
3.     {
4.         SimpleShader = Shader.Find("Custom/Simple");
5.         SimpleMaterial = new Material(SimpleShader);
6.     }
7. private void OnRenderImage(RenderTexture source, RenderTexture destination)
8.     {
9.         Graphics.Blit(source, destination, SimpleMaterial);
10.     }
11.  

Code (CSharp):

1.  
2. Shader "Custom/Simple"
3. {
4.     Properties
5.     {
6.         _MainTex ("Main Texture", 2D) = "black"{} // The source texture passed into Graphics.Blit.
7.     }
8.     SubShader
9.     {
10.         Tags { "Queue" = "Overlay" "RenderType" = "Overlay" }
11.         LOD 10
12.  
13.         Pass
14.         {
15.             CGPROGRAM
16. #pragma vertex vert_img
17. #pragma fragment frag
18. #include "UnityCG.cginc"
19.  
20.             fixed4 frag(v2f_img i) : SV_TARGET
21.             {
22.                 return fixed4(0.6f, 0.5f, 0.3f, 1.0f);
23.             }
24.             ENDCG
25.         }
26.     }
27.     FallBack Off
28. }
29.  

 

Got a little further and proved that a simple blit without material works fine but that the blit with material does nothing by first doing a copy with a simple blit like so:

Code (CSharp):

1.         Graphics.Blit(source, destination);
2.         // next blit doesn't alter anything to destination
3.         Graphics.Blit(source, destination, SimpleMaterial);

 

Maybe it will help:

Code (CSharp):

1.     void Blit(RenderTexture source, RenderTexture destination, Material mat)
2.     {
3.         RenderTexture.active = destination;
4.         mat.SetTexture("_MainTex", source);
5.         GL.PushMatrix();
6.         GL.LoadOrtho();
7.         GL.invertCulling = true;
8.         mat.SetPass(0);
9.         GL.Begin(GL.QUADS);
10.         GL.MultiTexCoord2(0, 0.0f, 0.0f);
11.         GL.Vertex3(0.0f, 0.0f, 0.0f);
12.         GL.MultiTexCoord2(0, 1.0f, 0.0f);
13.         GL.Vertex3(1.0f, 0.0f, 0.0f);
14.         GL.MultiTexCoord2(0, 1.0f, 1.0f);
15.         GL.Vertex3(1.0f, 1.0f, 1.0f);
16.         GL.MultiTexCoord2(0, 0.0f, 1.0f);
17.         GL.Vertex3(0.0f, 1.0f, 0.0f);
18.         GL.End();
19.         GL.invertCulling = false;
20.         GL.PopMatrix();      
21.     }

 

There is a setting in the player for android about blit.
https://docs.unity3d.com/ScriptReference/PlayerSettings.Android-blitType.html

Does messing with this setting produce different results?

 

Update: Graphics.Blit works fine with XR setting Multi Pass but not with Single Pass (at least not in 2018.3.3)
I'll test with the latest and submit a bug report if still present.

 

Filed case 1123989, thanks for looking into it.

 

Was there ever a fix for this one? I'm seeing it in 2019.1.0b1 on PC Standalone (DX11).

 

Note for people looking at this thread. I noticed the following documentation about needing to modify shaders for SinglePass. This might be relevant depending on what you are doing.

Look for section on

Graphics.Blit()
...

https://docs.unity3d.com/Manual/SinglePassStereoRendering.html

 

Graphics.Blit() works fine on _any_ Google Pixel phone, doesn't work on _any_ Samsung phone.

Explanation?

 

I have the same problem, with Unity 2019.1.9f1. It is only broken with OpenGLES2, not with Vulkan. This might be relevant as well.

 

We had the same problem. It seems that on some Android phones the Blit() operation doesn't turn off the depth test. Please make sure to use:

Code (CSharp):

1. ZTest Always

in the shader. In Editor, on iOS and many Android phones it wasn't necessary as Blit worked great and many of the old image shaders don't include this line.

 

Thank you so much! That did the trick for us

 

this help me too

 

Just wanted to add that I was having similar issues on the Oculus Quest 2 (though I wasn't just getting a black screen, but very weird artefacts that weren't even consistent between both eyes), and this fixed my problem as well.

 

Thank you, solved my issue also!

Just wanted to leave an example of the artifacts I was getting here:

 

For further triangulation, I did a PoC involving a (source,dest,mat) blit on Unity 2021.1.3 and it worked fine in editor and on Android target. Importing the identical files/packages/settings into a longstanding production project on 2020.3.8, (source,dest,mat) blits were mysteriously failing UNTIL I added the ZTest fix. So there's a chance this issue has its roots in how projects/resources are set up and what Unity version you're working in.
Spent most of a day total setting up debug UI and combing over project and build settings trying to find differences before just googling to see if this was a known issue :-/

 

Thanks, I solved my issue on android and ios