Question by Profed · Mar 18, 2018 at 11:26 AM · texture shaders uv mapping hlsl

A question about UVW.

Hello, everyone.

I'm working on volumetric clouds, and i've ran into an issue i'd like to know more about. So basically i use a compute shader to generate a 3D noise texture. It doesn't really matter.

Here is a part of debug shader i used to render my texture to a box while implementing noise compute shader:

 CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             
             #include "UnityCG.cginc"
 
             struct appdata
             {
                 float4 uvw : TEXCOORD0;
                 float4 vertex : POSITION;
             };
 
             struct v2f
             {
                 float3 uvw : TEXCOORD0;
                 float4 vertex : SV_POSITION;
             };
 
             sampler3D _MainTex;
 
             v2f vert (appdata v)
             {
                 v2f i;
                 i.vertex = UnityObjectToClipPos(v.vertex);
                 i.uvw = v.uvw.xyz;
                 return i;
             }
             
             fixed4 frag(v2f i) : COLOR
             {
                 fixed3 col = tex3D(_MainTex, i.uvw).r;
                 return fixed4(1.0 - col, 1.0);
             }

Nothing special here, but notice i take TEXCOORD0.

Taking TEXCOORD0 gives me this result:

alt text

Notice that it behaves as if it is a 2D texure, upper and lower planes are the same. So i've struggled a bit with that, and then changed a code to take TEXCOORD1.

Now it gives the right behaviour: alt text