Vertex color of unity shader

Overview: Use vertex color in unity to simply realize the gradient of the patch from bottom to top

---

1. Preliminary preparation

What are vertex colors used for?
Usually used for coloring by region

1. Model drawing vertex color method

• Draw in 3D software, such as Maya, 3Dmax, Blender, etc.
• Using plugins in unity

2. View the vertex color of the model

• View in 3D software
• Use the output in the fragment function in the shader

fixed4 frag (v2f i) : SV_Target{
    
    
	return i.vertColor;
}

2. Use vertex color data in the shader for simple coloring

1. Create a new shader and shader, assign the created shader to the shader, and assign the shader to the model.
2. shader attribute

Properties
	{
    
    
		_MainColor("顶部颜色",Color) = (1.0,1.0,1.0,1.0)
		_MainTex("顶部颜色贴图",2D) = "White"{
    
    }
		_SecondColor("底部颜色",Color) = (1.0,1.0,1.0,1.0)
		_SecondTex("底部颜色贴图",2D) = "White"{
    
    }
}

input structure

struct appdata
	{
    
    
		float4 vertex : POSITION;
		float2 uv : TEXCOORD0;
		float4 vertexColor : COLOR;    //输入顶点色数据
		};

Vertex function

v2f vert (appdata v)
	{
    
    
		v2f o;
		o.vertex = UnityObjectToClipPos(v.vertex);
		o.uv = TRANSFORM_TEX(v.uv, _MainTex);
		o.vertColor = v.vertexColor;        //顶点色
		return o;
	}

output structure

struct v2f
	{
    
    
		float2 uv : TEXCOORD0;
		float4 vertColor : TEXCOORD1;           //顶点色
		float4 vertex : SV_POSITION;
	};

statement definition

sampler2D _MainTex;  float4 _MainTex_ST;
sampler2D _SecondTex;  float4 _SecondTex_ST;
float4 _MainColor;
float4 _SecondColor;

Fragment function

fixed4 frag (v2f i) : SV_Target
	{
    
    
		//用顶点色vertColor.r的r通道是因为刚才在查看模型顶点色的时候看到的渐变是用红色通道。所以就拿r通道来制作及渐变
		fixed4 col = tex2D(_MainTex, i.uv) * _MainColor * i.vertColor.r + tex2D(_SecondTex, i.uv) * _SecondColor * (1.0 - i.vertColor.r );
		return col;
	}

---

full code

Shader "Unlit/vertexColor"
{
    
    
    Properties
    {
    
    
        _MainColor("Main Color",Color) = (1.0,1.0,1.0,1.0)
		_MainTex("MainTex",2D) = "White"{
    
    }
		_SecondColor("SecondColor",Color) = (1.0,1.0,1.0,1.0)
		_SecondTex("SecondTex",2D) = "White"{
    
    }
    }
    SubShader
    {
    
    
        Tags {
    
     "RenderType"="Opaque" }
        Pass
        {
    
    
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // make fog work
            #pragma multi_compile_fog

            #include "UnityCG.cginc"

            struct appdata
            {
    
    
                float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
				float4 vertexColor : COLOR;    //输入顶点色数据
            };

            struct v2f
            {
    
    
                float2 uv : TEXCOORD0;
				float4 vertColor : TEXCOORD1;           //顶点色
				float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;  float4 _MainTex_ST;
			sampler2D _SecondTex;  float4 _SecondTex_ST;
			float4 _MainColor;
			float4 _SecondColor;

            v2f vert (appdata v)
            {
    
    
                v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				o.vertColor = v.vertexColor;        //顶点色
				return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
    
    
            	//着色
                fixed4 col = tex2D(_MainTex, i.uv) * _MainColor * i.vertColor.r + tex2D(_SecondTex, i.uv) * _SecondColor * (1.0 - i.vertColor.r );
				return col;
            }
            ENDCG
        }
    }
}