Shader Help: Adding transparency to a shader.

Questions & Answers
1

I have been trying to make a shader that allows me to rotate the hue of a texture. I found one posted by gnoblin on this thread that performs that function perfectly. However as it is it does not support an alpha channel. I tried merging lines from some transparent shaders but in my ignorance had no luck.

If anyone can help me out or point me to some learning resources, I’d really appreciate it!

The shader I’m working with below:

Shader "HSB_HSV_Colorpicker" {

Properties {

  _MainTex ("Texture", 2D) = "white" {}
  _HueShift("HueShift", Float) = 0
}

SubShader {

  Tags { "RenderType" = "Opaque" }

  CGPROGRAM

  #pragma surface surf Lambert
  #pragma target 3.0

    float3 rgb_to_hsv_no_clip(float3 RGB)

    {

            float3 HSV;
       

     float minChannel, maxChannel;

     if (RGB.x > RGB.y) {

      maxChannel = RGB.x;
      minChannel = RGB.y;

     }

     else {

      maxChannel = RGB.y;
      minChannel = RGB.x;

     }

     

     if (RGB.z > maxChannel) maxChannel = RGB.z;

     if (RGB.z < minChannel) minChannel = RGB.z;
       

            HSV.xy = 0;

            HSV.z = maxChannel;

            float delta = maxChannel - minChannel;             //Delta RGB value

            if (delta != 0) {                    // If gray, leave H & S at zero

               HSV.y = delta / HSV.z;

               float3 delRGB;

               delRGB = (HSV.zzz - RGB + 3*delta) / (6.0*delta);

               if      ( RGB.x == HSV.z ) HSV.x = delRGB.z - delRGB.y;

               else if ( RGB.y == HSV.z ) HSV.x = ( 1.0/3.0) + delRGB.x - delRGB.z;

               else if ( RGB.z == HSV.z ) HSV.x = ( 2.0/3.0) + delRGB.y - delRGB.x;

            }

            return (HSV);

    }



    float3 hsv_to_rgb(float3 HSV)
    {

            float3 RGB = HSV.z;

       

               float var_h = HSV.x * 6;

               float var_i = floor(var_h);   // Or ... var_i = floor( var_h )

               float var_1 = HSV.z * (1.0 - HSV.y);

               float var_2 = HSV.z * (1.0 - HSV.y * (var_h-var_i));

               float var_3 = HSV.z * (1.0 - HSV.y * (1-(var_h-var_i)));

               if      (var_i == 0) { RGB = float3(HSV.z, var_3, var_1); }

               else if (var_i == 1) { RGB = float3(var_2, HSV.z, var_1); }

               else if (var_i == 2) { RGB = float3(var_1, HSV.z, var_3); }

               else if (var_i == 3) { RGB = float3(var_1, var_2, HSV.z); }

               else if (var_i == 4) { RGB = float3(var_3, var_1, HSV.z); }

               else                 { RGB = float3(HSV.z, var_1, var_2); }

       

       return (RGB);

    }



  struct Input {

      float2 uv_MainTex;

  };

 

  sampler2D _MainTex;

  float _HueShift;

 

  void surf (Input IN, inout SurfaceOutput o) {

      o.Albedo = tex2D (_MainTex, IN.uv_MainTex).rgb;
   

      float3 hsv = rgb_to_hsv_no_clip(o.Albedo.xyz);

      hsv.x+=_HueShift;
             

      if ( hsv.x > 1.0 ) { hsv.x -= 1.0; }

      o.Albedo = half3(hsv_to_rgb(hsv));



  }

 

  ENDCG

}

Fallback "Diffuse"

}

2

Success! Alright, I feel silly for posting this only to work it out myself. But I learned a ton about shaders in the process (mostly thanks to great Unity/community resources).

For anyone who is trying to Write a Surface Shader with Semi-Transparency take note of these lines:

.

I changed:

_MainTex ("Texture", 2D) = "white" {} 
Tags { "RenderType" = "Opaque" }

to:

_MainTex ("Color (RGB) Alpha (A)", 2D) = "white"
Tags { "Queue"="Transparent" "RenderType"="Transparent" }

.

Appended “alpha”:

#pragma surface surf Lambert alpha

.

Added this line after o.Albedo…

o.Alpha = tex2D (_MainTex, IN.uv_MainTex).a;

.

Seems pretty obvious in hindsight, but I hope this helps someone!

Note also that this shader lets you “rotate” the hue value of a texture.

3

Thanks for succinct guide, got it up and running in a few minutes with zero shader experience

4

For urp, this setup works much better:


		Tags {
			"RenderType"="Opaque"
			"Queue"="AlphaTest"
		}
		LOD 100
		
               Cull Off
                ZWrite On
                ZTest LEqual
                Blend One Zero
                **AlphaToMask On**
5

I am confused about using the package manager since it has been updated over the last several years. It used to be possible to import the standard assets package that came with unity which included several prefab character controllers to add to a scene. Since the standard assets have become legacy assets it isnt possible to do so without running into debug problems. Is there a way to use the project manager to quickly add prefab character controllers?