Force to use highp local variables in fragment shader on Android

Hello, I am using Unity 2020.1.0f1 and I need to get precise height data in fragment shader on Android.
This is necessary in order to draw beautiful elevation lines.

My shader (I've just simply modify and copy URP graph shader):

Code (CSharp):

1. Shader "Unlit Master"
2. {
3.     Properties
4.     {
5.         [NoScaleOffset]SurfaceHeightfield("SurfaceHeightfield", 2D) = "black" {}
6.     }
7.     SubShader
8.     {
9.         Tags
10.         {
11.             "RenderPipeline"="UniversalPipeline"
12.             "RenderType"="Opaque"
13.             "Queue"="Geometry+0"
14.         }
15.        
16.         Pass
17.         {
18.             Name "Pass"
19.             Tags
20.             {
21.                 // LightMode: <None>
22.             }
23.          
24.             // Render State
25.             Blend One Zero, One Zero
26.             Cull Back
27.             ZTest LEqual
28.             ZWrite On
29.             // ColorMask: <None>
30.            
31.        
32.             HLSLPROGRAM
33.             #pragma vertex vert
34.             #pragma fragment frag
35.        
36.             // Pragmas
37.             #pragma prefer_hlslcc gles
38.             #pragma exclude_renderers d3d11_9x
39.             #pragma target 3.5
40.             #pragma multi_compile_fog
41.             #pragma multi_compile_instancing
42.          
43.             // Keywords
44.             #pragma multi_compile _ LIGHTMAP_ON
45.             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
46.             #pragma shader_feature _ _SAMPLE_GI
47.             // GraphKeywords: <None>
48.            
49.             // Defines
50.             #define ATTRIBUTES_NEED_NORMAL
51.             #define ATTRIBUTES_NEED_TANGENT
52.             #define ATTRIBUTES_NEED_TEXCOORD0
53.             #define VARYINGS_NEED_TEXCOORD0
54.             #pragma multi_compile_instancing
55.             #define SHADERPASS_UNLIT
56.            
57.             #define PREFER_HALF 0
58.             #define SHADER_HINT_NICE_QUALITY 1
59.        
60.             // Includes
61.            
62.             ...
63.        
64.             // --------------------------------------------------
65.             // Graph
66.        
67.             // Graph Properties
68.             CBUFFER_START(UnityPerMaterial)
69.             CBUFFER_END
70.             TEXTURE2D_FLOAT(SurfaceHeightfield);
71.             SAMPLER(samplerSurfaceHeightfield);
72.             float4 SurfaceHeightfield_TexelSize;
73.             SAMPLER(SamplerState_Linear_Clamp);
74.        
75.             // Graph Vertex
76.             // GraphVertex: <None>
77.            
78.             // Graph Pixel
79.             struct SurfaceDescriptionInputs
80.             {
81.                 float4 uv0;
82.             };
83.            
84.             struct SurfaceDescription
85.             {
86.                 float3 Color;
87.                 float Alpha;
88.                 float AlphaClipThreshold;
89.             };
90.            
91.             SurfaceDescription SurfaceDescriptionFunction(SurfaceDescriptionInputs IN)
92.             {
93.                 SurfaceDescription surface = (SurfaceDescription)0;
94.  
95.                 surface.Color =
96.                     SurfaceHeightfield.Sample(SamplerState_Linear_Clamp, IN.uv0);
97.  
98.                 surface.Alpha = 1;
99.                 surface.AlphaClipThreshold = 0;
100.  
101.                 return surface;
102.             }
103.        
104.            ...
105.  
106.             ENDHLSL
107.         }
108.  
109.         ...
110.  
111.     }
112. }
113.  

I have added line 57 and 58 by myself:

#define PREFER_HALF 0
#define SHADER_HINT_NICE_QUALITY 1

After I press "compile and show code" and see this in glsl:

Code (CSharp):

1.  
2.  
3. ...
4.  
5. #ifdef VERTEX
6. #version 300 es
7.  
8. ...
9.  
10. in highp vec3 in_POSITION0;
11. in highp vec4 in_TEXCOORD0;
12. out highp vec4 vs_TEXCOORD0;
13. vec4 u_xlat0;
14. vec4 u_xlat1;
15. void main()
16. {
17.     u_xlat0.xyz = in_POSITION0.yyy * hlslcc_mtx4x4unity_ObjectToWorld[1].xyz;
18.     u_xlat0.xyz = hlslcc_mtx4x4unity_ObjectToWorld[0].xyz * in_POSITION0.xxx + u_xlat0.xyz;
19.     u_xlat0.xyz = hlslcc_mtx4x4unity_ObjectToWorld[2].xyz * in_POSITION0.zzz + u_xlat0.xyz;
20.     u_xlat0.xyz = u_xlat0.xyz + hlslcc_mtx4x4unity_ObjectToWorld[3].xyz;
21.     u_xlat1 = u_xlat0.yyyy * hlslcc_mtx4x4unity_MatrixVP[1];
22.     u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[0] * u_xlat0.xxxx + u_xlat1;
23.     u_xlat0 = hlslcc_mtx4x4unity_MatrixVP[2] * u_xlat0.zzzz + u_xlat1;
24.     gl_Position = u_xlat0 + hlslcc_mtx4x4unity_MatrixVP[3];
25.     vs_TEXCOORD0 = in_TEXCOORD0;
26.     return;
27. }
28.  
29. #endif
30. #ifdef FRAGMENT
31. #version 300 es
32.  
33. precision highp float;
34. precision highp int;
35.  
36. ...
37.  
38. UNITY_LOCATION(0) uniform highp sampler2D SurfaceHeightfield;
39. in highp vec4 vs_TEXCOORD0;
40. layout(location = 0) out highp vec4 SV_TARGET0;
41. mediump vec3 u_xlat10_0;
42. void main()
43. {
44.     u_xlat10_0.xyz = texture(SurfaceHeightfield, vs_TEXCOORD0.xy).xyz;
45.     SV_TARGET0.xyz = u_xlat10_0.xyz;
46.     SV_TARGET0.w = 1.0;
47.     return;
48. }
49.  
50. #endif
51.  

The problem is in line 41 :

mediump vec3 u_xlat10_0;

I need highp here. How can i archive that?

 

Perhaps #pragma fragmentoption ARB_precision_hint_nicest might do the trick!

 

Nope, does not work(

Unfortunately, as described here:
https://docs.unity3d.com/Manual/SL-ShaderPrograms.html

Directive "#pragma fragmentoption" deprecated and don't do anything.

 

That's very strange and interesting.

I have replaced line 95, 96 in shader by this:

surface.Color = SAMPLE_TEXTURE2D(SurfaceHeightfield, samplerSurfaceHeightfield, IN.uv0).xyz;

and then, success:

Code (CSharp):

1. #ifdef FRAGMENT
2. #version 300 es
3.  
4. ...
5.  
6. UNITY_LOCATION(0) uniform highp sampler2D SurfaceHeightfield;
7. in highp vec4 vs_TEXCOORD0;
8. layout(location = 0) out highp vec4 SV_TARGET0;
9. vec3 u_xlat0;
10. void main()
11. {
12.     u_xlat0.xyz = texture(SurfaceHeightfield, vs_TEXCOORD0.xy).xyz;
13.     SV_TARGET0.xyz = u_xlat0.xyz;
14.     SV_TARGET0.w = 1.0;
15.     return;
16. }
17.  
18. #endif

But if I change this line with (different SamplerState):

surface.Color = SAMPLE_TEXTURE2D(SurfaceHeightfield, SamplerState_Linear_Clamp, IN.uv0).xyz;

Again get precision reduction:

Code (CSharp):

1. #ifdef FRAGMENT
2. #version 300 es
3.  
4. ...
5.  
6. UNITY_LOCATION(0) uniform highp sampler2D SurfaceHeightfield;
7. in highp vec4 vs_TEXCOORD0;
8. layout(location = 0) out highp vec4 SV_TARGET0;
9. mediump vec3 u_xlat10_0;
10. void main()
11. {
12.     u_xlat10_0.xyz = texture(SurfaceHeightfield, vs_TEXCOORD0.xy).xyz;
13.     SV_TARGET0.xyz = u_xlat10_0.xyz;
14.     SV_TARGET0.w = 1.0;
15.     return;
16. }
17.  
18. #endif

Why this is happening?

 

Thank you for response!

Here it is:
https://fogbugz.unity3d.com/default.asp?1267645_besf6qcun6cpuf9v

 

Hello! Yes, I already did that.
But this is part of a much larger problem.
Our artists work with Shader Graph, and now I have to convert each of their shaders into code format and make patches. I am a little sad about this situation. (

 

Yes, ShaderGraph always creates custom SamplerState even if I do not use custom SamplerState ShaderGraph Node.
Plus there is no way to replace TEXTURE2D with TEXTURE2D_FLOAT only manual in code.
Plus there is no way to enable "#define PREFER_HALF 0" using ShaderGraph.

 

Yeah, of course. I will do it today)