Why does fixed4 fragment shader compile to mediump glsl shader?

Graphics Shaders & Materials
,
1

I have the following trivial fragment shader:

sampler2D _MainTex;

fixed4 unlitFrag(fragmentIn i) : SV_Target
{
  fixed4 col = tex2D(_MainTex, i.texcoord);
  return col;
}

Looking at the crosscompiled shader code for OpenGL ES 3.x I see:

#ifdef FRAGMENT
#version 310 es

precision highp float;
precision highp int;
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
UNITY_LOCATION(0) uniform mediump sampler2D _MainTex;
layout(location = 0) in highp vec2 gs_TEXCOORD0;
layout(location = 0) out mediump vec4 SV_Target0;
mediump vec4 u_xlat16_0;
void main()
{
    u_xlat16_0 = texture(_MainTex, gs_TEXCOORD0.xy);
    SV_Target0 = u_xlat16_0;
    return;
}

#endif

Why are the Sampler2D as well as SV_Target0 defined to have precision mediump rather than lowp?

2

Hi!
There are no OpenGL ES 3 devices that differentiate between lowp and mediump variables, so for GLES 3.x we generate mediump instead.