Write an unlit shader with color input in URP

1. Add the

   _BaseColor

   property definition to the Properties block:

   Properties{    [MainColor] _BaseColor("Base Color", Color) = (1, 1, 1, 1)}

   This declaration adds the

   _BaseColor

   property with the label Base Color to the Material:

   

   When you declare a property with the

   [MainColor]

   attribute, Unity uses this property as the main color of the Material.

   注

   For compatibility reasons, the

   _Color

   property name is a reserved name. Unity uses a property with the name

   _Color

   as the main color even it does not have the

   [MainColor]

   attribute.

2. When you declare a property in the Properties block, you also need to declare it in the HLSL code.

   注

   To ensure that the Unity shader is SRP Batcher compatible, declare all Material properties inside a single

   CBUFFER

   block with the name

   UnityPerMaterial

   . For more information on the SRP Batcher, refer to the documentation on the Scriptable Render Pipeline (SRP) Batcher.

   Add the following code before the vertex shader:

   CBUFFER_START(UnityPerMaterial)    half4 _BaseColor;CBUFFER_END

3. Change the code in the fragment shader so that it returns the

   _BaseColor

   property.

   half4 frag() : SV_Target{    return _BaseColor;}

// This shader fills the mesh shape with a color that a user can change using the// Inspector window on a Material.Shader "Example/URPUnlitShaderColor"{    // The _BaseColor variable is visible in the Material's Inspector, as a field    // called Base Color. You can use it to select a custom color. This variable    // has the default value (1, 1, 1, 1).    Properties    {        [MainColor] _BaseColor("Base Color", Color) = (1, 1, 1, 1)    }    SubShader    {        Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" }        Pass        {            HLSLPROGRAM            #pragma vertex vert            #pragma fragment frag            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"            struct Attributes            {                float4 positionOS   : POSITION;            };            struct Varyings            {                float4 positionHCS  : SV_POSITION;            };            // To make the Unity shader SRP Batcher compatible, declare all            // properties related to a Material in a a single CBUFFER block with            // the name UnityPerMaterial.            CBUFFER_START(UnityPerMaterial)                // The following line declares the _BaseColor variable, so that you                // can use it in the fragment shader.                half4 _BaseColor;            CBUFFER_END            Varyings vert(Attributes IN)            {                Varyings OUT;                OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);                return OUT;            }            half4 frag() : SV_Target            {                // Returning the _BaseColor value.                return _BaseColor;            }            ENDHLSL        }    }}