Shader error : Too many texture interpolators would be used for ForwardBase pass

[anon_65603996]

I get this error all the time: Too many texture interpolators would be used for ForwardBase pass
Here is the code where the error occurs, and the line where is the error is commented out.

SubShader {
Tags { “RenderType” = “Opaque” }
CGPROGRAM
#pragma surface surf Lambert vertex:vert
struct Input {
//float2 uv_MainTex; // here is the error
float3 color0;
float3 color1;
float3 normal;
float3 lightDir;
float4 position:POSITION;
};

[Tim-C]

@anon_65603996

I get this error all the time: Too many texture interpolators would be used for ForwardBase pass
Here is the code where the error occurs, and the line where is the error is commented out.

From an earlier thread

Hi,

In shader model 2.0 there are 8 general purpose vertex->fragment interpolators available. This means that you can pass a maximum of 8 float4’s (+ 2 color semantics but they are of lower precision so ignore them for the time being).

In shader model 3.0 you can have 10. In SM4.0 you can have 16 (expanded to 32 via geometry shaders). If your v2f interpolators go over these limits given the shader model then you will receive these errors.

brianasu was right when suggesting that you should pack your structure tighter, it’s the only way. If you do end up going over the limit, and can’t pack any more you will have to try and do more calculation in the PS (if possible).

It’s made more difficult because unity ‘pads’ out the structure with internal data in some passes that get compiled behind the scenes. It you look at that struct you could pack it like this:

float4 color0lightx;
float4 color1lighty;
float4 normallightz;

and then reconstruct the 4 floats3’s. This will give you some breathing room. Pack as much data as you can

[Revoluzifer]

I’ve got exactly the same error here but already repacked my struct as follows:

struct Input {
float2 uv_MainTex : TEXCOORD0;
float4 TtoW0Ix : TEXCOORD1;
float4 TtoW1Iy : TEXCOORD2;
float4 TtoW2Iz : TEXCOORD3;
float4 uv_Bumpvdxy : TEXCOORD4;
float4 vdzOSN;
};

Does anybody know another solution?

[anon_25929356]

Stupid solution: If you’re not targeting ancient hardware, just add “#pragma target 3.0” to make the shader compile to shader model 3.

[Dreamora]

Or just don’t use surface shaders if you intend to target ancient hardware, its not optimized for stonage (nor really suitable for mobile either just to mention)

I’m still curious on why it works at all without SM3 enforcement as it goes that close to the specs of SM2 that any hardware that really only supports SM2 will struggle and stutter seriously

[Revoluzifer]

Nice thing, thanks
But if I do that, 2 new errors appear:
Program ‘frag_surf’, assignment of incompatible types at line 136
and
Program ‘vert_surf’, assignment of incompatible types at line 136

Best thing: There are only 108 lines of code oO

Edit:
Didn’t see dreamora’s post…
Well, my problem is, I’m customizing an old shader.
Unity kind of told me to rewrite it into a surface shader.
Unfortunately i cannot remember the error-message for that…

[Revoluzifer]

No ideas on that?
I’m targeting pc only, so surface shader should work just fine I think.

I just cannot solve the errors mentioned above (assignment of incompatible types at line 136)…
I do not have a line 136 - or is it the compiled shader’s line?
Getting really confused at the moment…

[Ravel]

sorry to bump such an old thread, but my shader just stopped working. I compared it to an older version of the shader and the code is 1:1 the same. Only problem is that, now I get the same issue. Is there some sort of online checkups in Unity 5.6 ? And if there is, why isn’t this fixed instead?

[JonPQ]

going from 5.6 to 2019… the number of interpolaters has apparently gone down. some of my shaders no longer compile…

[voxellstudios]

i fixed it by changing #pragma target 3.0 to #pragma target 4.0. can someone tell me if this will affect the performance of the game?

[danielpokladek]

@voxellstudios

i fixed it by changing #pragma target 3.0 to #pragma target 4.0. can someone tell me if this will affect the performance of the game?

You can read up more about shader targets in Unity’s manual:
https://docs.unity3d.com/Manual/SL-ShaderCompileTargets.html

As far as my understanding goes it shouldn’t, but the shader can be unavailable on certain (especially old) hardware, and as mentioned before because surface shaders aren’t meant to be used on mobile it can cause issues there.

[andyz]

digging up because I had to add #pragma target 3.5 just to add one custom float2 on top of Input with
float2 uv_MainTex;
float3 worldRefl;

Don’t understand why a basic surface shader can require 10 texture interpolators!! But I guess it is because it compiles for every possible use case including 4 textures, even I only have 1 defined?! I don’t really get it…
I can add/modify the vertex shader to use appdata_base or appdata_tan instead of appdata_full, which generates warnings about not supporting some use-cases (lightmaps, dynamic GI). But not an issue if I don’t use those is it?!

Unity 2019 LTS