Question by soriak · Mar 26, 2018 at 01:24 PM · scripting problem shader image effects post

How to accurately map UV from second texture in image effects

Hi,

I wrote a simple shader to apply the red and green channel of a "UV Texture" to the Maintexture in a ImageEffect.

it looks like this:

         Texture2D _UVTex;
         SamplerState my_linear_clamp_sampler;
         Texture2D _MainTex;


         fixed4 frag (v2f i) : SV_Target
         {
             float4 uvVals = _UVTex.Sample(my_linear_clamp_sampler, i.uv);
             fixed4 col = _MainTex.Sample(my_linear_clamp_sampler, float2(uvVals[0],uvVals[1]));
             //fixed4 col = tex2D(_MainTex, i.uv);
             // just invert the colors
             //col.rgb = 1 - col.rgb;
             return col;
         }

I created the "UV Texture" like this:

         UVTexture = new Texture2D(Display.main.renderingWidth, Display.main.renderingHeight, TextureFormat.ARGB32, false, true);

         float[] wh = { UVTexture.width, UVTexture.height };

         for (int y = 0; y < UVTexture.height; y++)
         {
             for (int x = 0; x < UVTexture.width; x++)
             {
                 UVTexture.SetPixel(x, y, new Color(x / wh[0], y / wh[1], 0, 1));
             }
         }

         UVTexture.Apply();

what I expect from this UVTexture is to not alter the output at all as I am generating an Image that linearily moves from green to red over the whole image. However, when I press play on a Scene with nothing in it but a plane, i can clearly see, that the plane slightly appears to shrink in size, as if there was something not accurate about my sampling/generating....

here is what it looks like: alt text