Resolved Grass Compute shader appearing pink in mobile.

I have been trying out a grass compute shader by minionsart from patreon and it works awesome in pc but even though my mobile supports compute shaders, The grass appears pink on a sphere with no wind sway while it should have been all over a plane moving with the wind. if the shader code is important in analyzing this, please tell me.
Here are some images..

 

Did you try in windows standalone build?
If not there put the shader in always included shaders

 

Yes but the shader works fine when put in unity remote in my mobile but when i build the games apk, this happens.

 

It works fine in the windows standalone build.

 

and by the way, I use URP (LWRP)

 

URP or LWRP?
And what unity version? Tried the latest lts already?

Oh wait, do you use vulkan? openGL doesn't support compute shaders well

 

Just in case you're not aware Unity Remote doesn't actually run your application on your mobile device. Instead it's running your application on your PC and simply passing the rendered output of the PC to the mobile device and the inputs of the mobile device back to the PC.

 

You could also check Shader.isSupported

 

I use URP unity 2021.3.4f1 and after you posted this, i found that vulcan wasn't added to my graphics api list in project settings so when I tried to put it on, unity crashed.

Oh.. I didn't know that since i'm a beginner to developing to mobile.

I will try that.

Yes you are right... I found the device log via command prompt and this is the error

 GLSL link error:  The number of vertex shader storage blocks (1) is greater than the maximum number allowed (0).

How do I fix this?

 

The error above is from one of the grass shader files. Here is the code.

Code (CSharp):

1. Shader "Custom/GrassComputeHLSL"
2. {
3.     Properties
4.     {
5.         [Toggle(BLEND)] _BlendFloor("Blend with floor", Float) = 0
6.         _Fade("Top Fade Offset", Range(-1,10)) = 0
7.         _AmbientAdjustment("Ambient Adjustment", Range(-1,10)) = 0
8.     }
9.    
10.     HLSLINCLUDE
11.     // Include some helper functions
12.     #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
13.     #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"
14.     #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Shadows.hlsl"
15.    
16.     // This describes a vertex on the generated mesh
17.     struct DrawVertex
18.     {
19.         float3 positionWS; // The position in world space
20.         float2 uv;
21.         float3 diffuseColor;
22.     };
23.    
24.     // A triangle on the generated mesh
25.     struct DrawTriangle
26.     {
27.         float3 normalOS;
28.         DrawVertex vertices[3]; // The three points on the triangle
29.     };
30.    
31.     // A buffer containing the generated mesh
32.     StructuredBuffer<DrawTriangle> _DrawTriangles;
33.    
34.     struct v2f
35.     {
36.         float4 positionCS : SV_POSITION; // Position in clip space
37.         float2 uv : TEXCOORD0;          // The height of this vertex on the grass blade
38.         float3 positionWS : TEXCOORD1; // Position in world space
39.         float3 normalWS : TEXCOORD2;   // Normal vector in world space
40.         float3 diffuseColor : COLOR;
41.         float fogFactor : TEXCOORD5;
42.     };
43.    
44.     float4 _TopTint;
45.     float4 _BottomTint;
46.     float _Fade;
47.     float4 _PositionMoving;
48.     float _OrthographicCamSize;
49.     float3 _OrthographicCamPos;
50.     uniform sampler2D _TerrainDiffuse;
51.     float _AmbientAdjustment;
52.     // ----------------------------------------
53.    
54.     // Vertex function
55.    
56.     // -- retrieve data generated from compute shader
57.     v2f vert(uint vertexID : SV_VertexID)
58.     {
59.         // Initialize the output struct
60.         v2f output = (v2f)0;
61.        
62.         // Get the vertex from the buffer
63.         // Since the buffer is structured in triangles, we need to divide the vertexID by three
64.         // to get the triangle, and then modulo by 3 to get the vertex on the triangle
65.         DrawTriangle tri = _DrawTriangles[vertexID / 3];
66.         DrawVertex input = tri.vertices[vertexID % 3];
67.        
68.         output.positionCS = TransformWorldToHClip(input.positionWS);
69.         output.positionWS = input.positionWS;
70.        
71.         float3 faceNormal = GetMainLight().direction * tri.normalOS;
72.         output.normalWS = TransformObjectToWorldNormal(faceNormal, true);
73.         float fogFactor = ComputeFogFactor(output.positionCS.z);
74.         output.fogFactor = fogFactor;
75.         output.uv = input.uv;
76.        
77.         output.diffuseColor = input.diffuseColor;
78.        
79.         return output;
80.     }
81.    
82.     // ----------------------------------------
83.    
84.     // Fragment function
85.    
86.     half4 frag(v2f i) : SV_Target
87.     {
88.         // For Shadow Caster Pass
89.         #ifdef SHADERPASS_SHADOWCASTER
90.             return 0;
91.         #else
92.             // For Color Pass
93.             // rendertexture UV for terrain blending
94.             float2 uv = i.positionWS.xz - _OrthographicCamPos.xz;
95.             uv = uv / (_OrthographicCamSize * 2);
96.             uv += 0.5;
97.            
98.             // get ambient color from environment lighting
99.             float4 ambient =float4(unity_SHAr.w, unity_SHAg.w, unity_SHAb.w,1); //float4(ShadeSH9(float4(0,0,1,1)),0);
100.            
101.             float shadow = 0;
102.             #if BLEND
103.                 shadow = 1;              
104.             #endif
105.            
106.            
107.             half4 shadowCoord = TransformWorldToShadowCoord(i.positionWS);
108.            
109.             #if _MAIN_LIGHT_SHADOWS_CASCADE || _MAIN_LIGHT_SHADOWS
110.                 Light mainLight = GetMainLight(shadowCoord);
111.                 shadow = mainLight.shadowAttenuation;
112.             #else
113.                 Light mainLight = GetMainLight();
114.             #endif
115.            
116.             // extra point lights support
117.             float3 extraLights;
118.             int pixelLightCount = GetAdditionalLightsCount();
119.             for (int j = 0; j < pixelLightCount; ++j) {
120.                 Light light = GetAdditionalLight(j, i.positionWS, half4(1, 1, 1, 1));
121.                 float3 attenuatedLightColor = light.color * (light.distanceAttenuation * light.shadowAttenuation);
122.                 extraLights += attenuatedLightColor;
123.                
124.             }
125.             // fade over the length of the grass
126.             float verticalFade = saturate(i.uv.y + _Fade);
127.             extraLights *= verticalFade;
128.             // colors from the tool with tinting from the grass script
129.             float4 baseColor = lerp(_BottomTint , _TopTint,verticalFade) * float4(i.diffuseColor, 1);
130.             // get the floor map
131.             float4 terrainForBlending = tex2D(_TerrainDiffuse, uv);
132.            
133.             float4 final = float4(0,0,0,0);
134.             #if BLEND    
135.                 _TopTint = _TopTint * ambient;
136.                 // tint the top blades and add in light color            
137.                 terrainForBlending = lerp(terrainForBlending,terrainForBlending+ ( _TopTint* float4(i.diffuseColor, 1)) , verticalFade);
138.                 final = lerp((terrainForBlending)  * shadow , terrainForBlending, shadow);
139.                 // add in ambient and attempt to blend in with the shadows
140.                 final += lerp((ambient * terrainForBlending) * _AmbientAdjustment, 0,shadow);
141.             #else
142.                 final = baseColor;
143.                 // add in shadows
144.                 final *= shadow;
145.                 // if theres a main light, multiply with its color and intensity          
146.                 final *= float4(mainLight.color,1);        
147.                
148.                 // add in ambient
149.                 final += (ambient * baseColor) ;
150.             #endif
151.             final += float4(extraLights,1);
152.             // fog
153.             float fogFactor = i.fogFactor;
154.             // Mix the pixel color with fogColor.
155.             final.rgb = MixFog(final.rgb, fogFactor);        
156.             return final;
157.            
158.         #endif  // SHADERPASS_SHADOWCASTER
159.     }
160.     ENDHLSL
161.    
162.     SubShader {
163.         // UniversalPipeline needed to have this render in URP
164.         Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" "IgnoreProjector" = "True" }
165.        
166.         // Forward Lit Pass
167.         Pass
168.         {
169.             Name "ForwardLit"
170.             Tags { "LightMode" = "UniversalForward" }
171.             Cull Off // No culling since the grass must be double sided
172.            
173.             HLSLPROGRAM
174.             // Signal this shader requires a compute buffer
175.             #pragma prefer_hlslcc gles
176.             #pragma exclude_renderers d3d11_9x
177.             #pragma target 5.0
178.            
179.             // Lighting and shadow keywords
180.             #pragma multi_compile _ _MAIN_LIGHT_SHADOWS
181.             #pragma multi_compile _ _MAIN_LIGHT_SHADOWS_CASCADE
182.             #pragma multi_compile _ _ADDITIONAL_LIGHTS
183.             #pragma multi_compile _ _ADDITIONAL_LIGHT_SHADOWS
184.             #pragma multi_compile _ _SHADOWS_SOFT
185.             #pragma multi_compile_fog
186.             #pragma shader_feature BLEND
187.             // Register our functions
188.             #pragma vertex vert
189.             #pragma fragment frag
190.            
191.             ENDHLSL
192.         }
193.        
194.         // Shadow Casting Pass
195.         Pass
196.         {
197.             Name "ShadowCaster"
198.             Tags { "LightMode" = "ShadowCaster" }
199.             ZWrite On
200.             ZTest LEqual
201.             Cull Off
202.            
203.             HLSLPROGRAM
204.             // Signal this shader requires geometry function support
205.             #pragma prefer_hlslcc gles
206.             #pragma exclude_renderers d3d11_9x
207.             #pragma target 5.0
208.            
209.             // Support all the various light  ypes and shadow paths
210.             #pragma multi_compile_shadowcaster
211.            
212.             // Register our functions
213.             #pragma vertex vert
214.             #pragma fragment frag
215.            
216.             // A custom keyword to modify logic during the shadow caster pass
217.             #define SHADERPASS_SHADOWCASTER
218.            
219.             #pragma shader_feature_local _ DISTANCE_DETAIL
220.            
221.             ENDHLSL
222.         }
223.     }
224. }

 

Oh ok then... I will try to change the implementation.

 

Using vulkan under android might fix this right?

@codevisionary005 did you add vulkan under android or desktop? You can use it for android and use automatic for desktop

 

One alternative is to use a RenderTexture instead of a ComputeBuffer. They are less flexible to work with, but reading from textures on vertex shaders should be supported on ES 3.0 and up.

 

I tried to, but wheneven I add vulcan, Unity crashes.

The ComputeBuffer is read-only but as I said earlier, I couldn't add vulcan since unity crashes.

Do you have any resources for RenderTexture? Because i'm new to shader programming and i'm do not know if it could help me generate grass blades as the computebuffer does.

 

But unity shouldn't crash if you change the android API. Unity itself should still run in dx11 in that case. Do make a bug report (after trying the latest LTS of your unity version) for it since it shouldn't happen

 

Good news. After @DevDunk told me to try the latest LTS of my unity version, I tried it. It didn't work, but then I tried 2021.3.0f1 which is a version older than what I currently use, The shader now works! Thank you for all your help, I will be changing the thread's tag to resolved.

 

Could you make a bug report on the latest lts in that case?
To get the issue fixed