Seamless texture shader unlit query

Unity Engine
1

I have no experience with shaders, but it looks like I might have to learn! I just wondered if someone can confirm whether this is possible before I dive in?

I need a shader that will modify uvs in order to “line up” a texture across adjacent objects (2D), so that it looks seamless.

The shader posted in an answer here does what I want, except I don’t need/want lighting. My question is whether this is possible without using a Surface shader? The docs state not to use surface shaders if the surface isn’t using light, I guess for performance.

2 
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
 
sampler2D _MainTex;
float4 _Color;
float _Scale;
 
struct vOut {
float4 texCoords;
};
 
vOut vert ( appdata_base i )
{
vOut o;
float3 worldNormal = normalize( mul( float4( i.normal, 0.0 ), _World2Object ).xyz );
float3 worldPos = mul( UNITY_MATRIX_MVP, i.vertex );
o.texCoords = i.texcoord;

if(worldNormal.y>0.5) UV = o.texCoords.xy = worldPos.xz;
else if(abs(worldNormal.x)>0.5) o.texCoords.xy = worldPos.yz; // side
else o.texCoords.xy = worldPos.xy;

return o;
}

fixed4 frag ( vOut f )
{
fixed4 mainTex = tex2D( _MainTex, f.texCoords.xy * _Scale) * _Color;
return mainTex;
}

ENDCG

That’s a vertex/fragment shader that I think may do something similar to what the subshader does. There may be some errors in places but it’s the basic idea.

3

Thank you that’s very helpful! I’m working through the errors, but stuck on one at the moment.

4

Try

fixed4 frag ( vOut f ) : COLOR
5

Thanks. The texture is now showing and is “seamless”, but the texture “moves” with the camera. I thought using another built in matrix might fix it but no luck.
Thanks for the help and sorry for being a bit useless :slight_smile:

Shader "Custom/SimpleUnlitWorldAligned" {
	Properties { 
	 	_MainTex ("Texture", 2D) = ""
		_Scale ("Texture Scale Multiplier", Float) = 0.1 
	}

	SubShader { 
		Pass {
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag 
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			float _Scale;

			struct vOut {
				float4 texCoords;
				float4 position : POSITION;
			};

			vOut vert ( appdata_base i )
			{
				vOut o;
				o.position = mul (UNITY_MATRIX_MVP, i.vertex);
				
				float3 worldNormal = normalize( mul( float4( i.normal, 0.0 ), _World2Object ).xyz );
				float3 worldPos =  (float3) mul( UNITY_MATRIX_MV, i.vertex );
				o.texCoords = i.texcoord; 

				if(worldNormal.y>0.5) 
					o.texCoords.xy = worldPos.xz; // top
				else if(abs(worldNormal.x)>0.5) 
					o.texCoords.xy = worldPos.yz; // side
				else 
					o.texCoords.xy = worldPos.xy; // front			

				return o;
			}

			fixed4 frag ( vOut f ) : COLOR
			{
				fixed4 mainTex = tex2D( _MainTex, f.texCoords.xy * _Scale);
				return mainTex;
			}

			ENDCG
		}
	}
}
6

OK this seems to be working. Just one warning now!

vOut vert ( appdata_base i )
{
	vOut o;
	o.position = mul (UNITY_MATRIX_MVP, i.vertex);
	
	float3 worldNormal = normalize( mul( _Object2World, float4( i.normal, 0.0 ) ).xyz );
	float3 worldPos = mul (_Object2World, i.vertex).xyz;
	o.texCoords = i.texcoord; 

	if(worldNormal.y>0.5) 
		o.texCoords.xy = worldPos.xz; // top
	else if(abs(worldNormal.x)>0.5) 
		o.texCoords.xy = worldPos.yz; // side
	else 
		o.texCoords.xy = worldPos.xy; // front			

	return o;
}

Warning:

Will have another look on Monday.

7

Seems OK now. Here’s the final shader. Don’t ask me if it’s perfect. :stuck_out_tongue:

Shader "Custom/UnlitWorldAligned2D" {
	Properties { 
	 	_MainTex ("Texture", 2D) = ""
		_Scale ("Texture Scale Multiplier", Float) = 0.1 
	}

	SubShader { 
		Pass {
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag 
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			float _Scale;

			struct vOut {
				fixed4 texCoords : TEXCOORD0;
				fixed4 position : POSITION;
			};

			vOut vert (appdata_base i) {
				vOut o;				
				o.position = mul(UNITY_MATRIX_MVP, i.vertex);
				o.texCoords = i.texcoord;
				
				float3 worldPos = mul(_Object2World, i.vertex).xyz;		
		
				// remove comments on following lines for a 3D shader							
		//		float3 worldNormal = normalize(mul(float4(i.normal, 0.0 ), _World2Object).xyz);
		//		if (worldNormal.y > 0.5) 
		//			o.texCoords.xy = worldPos.xz; // top
		//		else if (abs(worldNormal.x) > 0.5) 
		//			o.texCoords.xy = worldPos.yz; // side
		//		else 
					o.texCoords.xy = worldPos.xy; // front			

				return o;
			}

			fixed4 frag (vOut f) : COLOR {
				fixed4 mainTex = tex2D(_MainTex, f.texCoords.xy * _Scale);
				return mainTex;
			}

			ENDCG
		}
	}
}
8

thank you sooooooooooooo much, thank you sooooo sooo sooo much. i was about to ask a doubt but while typing itself i found the answer. for those who cant get the texture repeated, change the texture from clamped to repeat mode in inspector. thank you soo much guys. love you all

9

Hey looks it’s 2018 and I just had to tip my hat to Hamstar, Shader works like a dream
<3