Issue with transparency on IOS device (becomes black).

Hello.

I made a shader for a mobile application.
Everything it's okay on many devices but the for some IOS devices the transparency doesn't seems to work (for now the issue appear on an IPhone6).
The parts that should be transparent are totally black , I made several attempts to correct this problem without maniage to find a proper sollution.

I copy/paste here the code, in case of someone know why.

Code (csharp):

1. Shader "Name"
2. {
3.     //Versio 05 _ 30/03 - 15h40
4.     Properties
5.     {
6.         _MainTex("Texture", 2D) = "white" {}
7.         _si2("Jauge",Range(0, 1)) = 0
8.         _Color("Color", Color) = (0.,0.,0.,1.)
9.         _s("ActivationEffet",Range(0, 1)) = 0
10.        
11.     }
12.         SubShader
13.         {
14.                 Tags {
15.                 "Queue" = "Transparent"
16.                 "IgnoreProjector" = "True"
17.                 "RenderType" = "Transparent" }
18.  
19.                 ZTest Always
20.                 Blend SrcAlpha OneMinusSrcAlpha
21.                 Cull Off Lighting Off ZWrite Off
22.             Pass
23.             {
24.                 CGPROGRAM
25.                 #pragma vertex vert
26.                 #pragma fragment frag
27.                 #include "UnityCG.cginc"
28.                 #pragma target 3.0
29.                 struct appdata
30.                 {
31.                     float4 vertex : POSITION;
32.                     float2 uv : TEXCOORD0;
33.                 };
34.                 struct v2f
35.                 {
36.                     float2 uv : TEXCOORD0;
37.                     float4 vertex : SV_POSITION;
38.                 };
39.                 sampler2D _MainTex;
40.                 half4 _MainTex_ST;
41.                 half _s;
42.                 half _si2;
43.                 half4 _Color;
44.                 v2f vert(appdata v)
45.                 {
46.                     v2f o;
47.                     o.vertex = UnityObjectToClipPos(v.vertex);
48.                     o.uv = TRANSFORM_TEX(v.uv, _MainTex);
49.                     return o;
50.                 }
51.                 float ov(float base, float blend) {
52.                     return lerp((2.0 * base * blend) , (1.0 - 2.0 * (1.0 - base) * (1.0 - blend)),step(0.5,base));
53.                 }
54.  
55.                 fixed4 frag(v2f i) : SV_Target
56.                 {
57.                     float time = _Time * 20.;
58.                     float2 uv = (i.uv - 0.5) * 5.;
59.                     float d = length(uv);
60.                     float z = sqrt(1.0 - d * d);
61.                     float val = _si2;
62.                     float pa = (lerp(lerp(lerp(pow(frac(val * 2.), 0.18) * 0.5, (1. - pow(1. - frac(val * 2.), 0.18) * 0.5), step(0.5, val)), 10., step(0.999, val)), -10., step(val, 0.001)) - 0.5) * z * 10.;
63.                     float si = 0.03;
64.                     float ba = smoothstep(pa - si, pa + si, uv.x);
65.                     float m = smoothstep(0.985, 0.975, d);
66.                     float m2 = smoothstep(1.11, 1.09,d);
67.                     float fn2 = lerp(1.,ba,  m);;
68.                     float i1 = pow(_s, 10.);
69.                     float fn = lerp(fn2, 1., i1);
70.                     return fixed4(saturate(float3(fn,fn,fn)),m2);
71.                 }
72.  
73.                 ENDCG
74.             }
75.         }
76. }
77.  

thx.

 

For more precision
the specs of the mobile are :


<color=red>SYSTEM INFO</color>
[iphone generation]iPhone6
[type]Handheld
[os version]iOS 12.4.5
[system memory size]989
[graphic device name]Apple A8 GPU (version Metal)
[graphic memory size]256
[graphic max texSize]8192
[graphic shader level]45
[support compute shader]True
[support gyro]True
[support accelero]True
[processor count]2
[processor type]arm64
[support 3d texture]True
[support shadow]True
[platform] IPhonePlayer
[screen size] 750 x 1334
[screen pixel density dpi] 326


apple A8 / Metal
graphic shader level 45

 

Hi,

I try to replace the float by fixed, to add a fallback and to only make math operation with variables but the problem is still there.
I also try to pass the shader model in 2.0 / 3.0 / 3.5.
some examples of the modifications.

Code (CSharp):

1. Shader "Unmaze/MiniLune"
2. {
3.     //Versio 13 _ 30/03 - 18h50
4.     Properties
5.     {
6.  
7.         _MainTex ("Texture", 2D) = "white" {}
8.  
9.         _si2("Jauge",Range(0, 1)) = 0
10.         _Color ("Color", Color) = (0.,0.,0.,1.)
11.         _s("ActivationEffet",Range(0, 1)) = 0
12.        
13.     }
14.     SubShader
15.     {
16.             Tags {
17.             "Queue" = "Overlay"
18.             "IgnoreProjector" = "True"
19.             "RenderType" = "Transparent" }
20.        
21.             ZTest Always
22.             Blend SrcAlpha OneMinusSrcAlpha
23.             Cull off Lighting Off ZWrite Off
24.  
25.         Pass
26.         {
27.             CGPROGRAM
28.             #pragma vertex vert
29.             #pragma fragment frag
30.             #include "UnityCG.cginc"
31.             #pragma target 3.0
32.             #pragma fragmentoption ARB_precision_hint_fastest
33.             struct appdata
34.             {
35.                 float4 vertex : POSITION;
36.                 float2 uv : TEXCOORD0;
37.             };
38.  
39.             struct v2f
40.             {
41.                 float2 uv : TEXCOORD0;
42.                 float4 vertex : SV_POSITION;
43.             };
44.  
45.             uniform sampler2D _MainTex;
46.             uniform float4 _MainTex_ST;
47.             uniform float _s;
48.             uniform float _si2;
49.             uniform float4 _Color;
50.             v2f vert (appdata v)
51.             {
52.                 v2f o;
53.                 o.vertex = UnityObjectToClipPos(v.vertex);
54.                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
55.                 return o;
56.             }
57.             float ov(float base, float blend) {
58.                 return lerp((2.0 * base * blend) , (1.0 - 2.0 * (1.0 - base) * (1.0 - blend)),step(0.5,base));
59.             }
60.  
61.             fixed4 frag(v2f i) : SV_Target
62.             {
63.                 fixed time = _Time.y;
64.                 float2 uv = (i.uv - 0.5) * 5.;
65.                 fixed d = length(uv);
66.                 fixed z = sqrt(1.0 - d * d);
67.                 fixed m = smoothstep(0.985, 0.975, d);
68.                 fixed m2 = smoothstep(1.11, 1.09, d);
69.                 fixed val = _si2;
70.                 fixed i1 = pow(_s, 10.);
71.                 fixed fp1 = frac(val * 2.);
72.                 fixed fp2 = pow(fp1, 0.18) * 0.5;
73.                 fixed fp3 = 1. - fp1;
74.                 fixed fp4 = 1. - pow(fp3, 0.18) * 0.5;
75.                 fixed fp5 = step(0.5, val);
76.                 fixed fp6 = step(0.999, val);
77.                 fixed fp7 = step(val, 0.001);
78.                 fixed pa1 = lerp(fp2, fp4, fp5);
79.                 fixed pa2 = lerp(pa1, 10., fp6);
80.                 fixed pa3 = (lerp(pa2, -10., fp7) - 0.5) * z * 10.;
81.                 fixed si = 0.03;
82.                 fixed ba = smoothstep(pa3 - si, pa3 + si, uv.x);              
83.                 fixed fn2 = lerp(1.,ba,  m ) ;
84.                 fixed fn = lerp(fn2, 1., i1);
85.                 fixed3 fin = saturate(fixed3(fn, fn, fn));
86.                 return fixed4(fin,m2);
87.             }
88.                
89.             ENDCG
90.         }
91.            
92.     }
93.             Fallback "Particles/Standard Unlit"
94. }
95.  

I don't know if I missing something with some spec for IOS...

 

If you hardcode the m2 value as, say, 0.5, does transparency then work?

 

Hi,
I try to pass m2 to 0.5 the center part get transparent but outside it's still black.

I remplace this line :
" float2 uv = (i.uv - 0.5) * 5.; " by :
" float2 uv = (i.uv - float2(0.5, 0.5)) * float2(5.,5.); "

assuming that maybe the fact that I didn't explicit all the value was making a trouble on the alpha, but the problem persist.

 

If I removed the line 83 :
- fixed fn2 = lerp(1.,ba, m ) ;
and pass "fixed ba" directly in the result I get the transparency but it's very weird, the circle around( that is in this case is black in the editor) became whit in the Iphone.

This is an image the differents results :



I don't get why when I add a simple lerp whith a 1.0 value in the emmissive that destroy the transparency and why the color pass to the white.

 

I tried with nodal editors, but the problems remains...

 

Ok, resolved by adding a max() with a 0.001 value inside the sqrt oparation.

 

Does anyone knows where I can find informations on do's and don'ts for iOS ?