Shader入门精要笔记 - CH9_阴影投射，接收阴影

 

要点

1) 阴影投射一般直接引用unity自带的，比如：

FallBack "VertexLit"

FallBack "Transparent/Cutout/VertexLit" //针对半透明物体的情况

里面都包含名叫ShadowCaster的Pass来处理阴影投射

 

2) 接收阴影只需要用3个宏加几行代码就行了

SHADOW_COORDS(texIndex)

TRANSFER_SHADOW(appdata)

SHADOW_ATTENUATION(v2f)

 

主贴图漫反射(MainTex)+高光反射+阴影投射+接收阴影

Shader "My/Light/Shadow_CastAndRecv"
{
    Properties
    {
        _MainTex("Main Tex", 2D) = "white" {}
        _Color("Diffuse Color", Color) = (1, 1, 1, 1)

        _Specular("Specular", Color) = (1, 1, 1, 1) //高光反射颜色
        _Gloss("Gloss", Range(8.0, 256)) = 20 //高光区域大小
    }
    SubShader
    {
        Pass
        {
            Tags { "LightMode" = "ForwardBase" }

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile_fwdbase

            #include "Lighting.cginc"
            #include "AutoLight.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL; //顶点法线
                float2 texcoord : TEXCOORD0;
            };

            struct v2f
            {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD0;
                float3 worldNormal : TEXCOORD1;
                float3 worldPos: TEXCOORD2;
                SHADOW_COORDS(3)
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;
            fixed4 _Color;
            fixed _Cutoff;

            fixed4 _Specular;
            float _Gloss;

            v2f vert(appdata v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldNormal = UnityObjectToWorldNormal(v.normal);
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

                o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                TRANSFER_SHADOW(o);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos)); //指向光源向量(世界空间)

                fixed4 texColor = tex2D(_MainTex, i.uv);

                fixed3 albedo = texColor.rgb * _Color.rgb; //取贴图颜色作为漫反射颜色
                fixed3 ambientColor = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo; //环境光

                fixed lambert = max(0, dot(worldNormal, worldLightDir)); //表面法线和光线方向夹角的cos值成正比
                fixed3 diffuseColor = _LightColor0.rgb * albedo * lambert; //漫反射计算公式

                fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos)); //视线方向(顶点到相机)

                fixed3 halfDir = normalize(worldLightDir + viewDir); // blinn模型引入的h向量
                fixed3 specularColor = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(worldNormal, halfDir)), _Gloss); // blinn模型高光反射计算公式(更亮, 高光区域更大)

                //fixed atten = 1.0; //衰减
                //fixed shadow = SHADOW_ATTENUATION(i); //接收阴影
                //atten *= showdow;

                UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos); //光照衰减+接收阴影宏

                return fixed4(ambientColor + (diffuseColor + specularColor) * atten, 1);
            }
            ENDCG
        }
    }

    FallBack "VertexLit" //引用它的ShadowCaster的Pass
}