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.
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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.
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Taking TEXCOORD0 gives me this result:
![alt text][1]
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][2]
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**So the question is:**
Can someone briefly explain why doe's it work like that, or maybe point to a good advanced artice where can i read more about that?
The scale is not an problem, but as you can see it also changes, changing the TEXCOORD index, would be nice to know why, also.
I know this does matter on low level stuff and DirectX implemetation of Unity, but can't tie it all together :(
[1]: /storage/temp/113236-screenshot-1.png
[2]: /storage/temp/113237-screenshot-2.png
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