shader学习基础之四（语法规范以及光照模型）

基础篇（四）

shader结构解析：

{
_Color ("Color", Color) = (1,1,1,1)
内部变量名（"界面名称"，属性类型）=属性默认值;
_MainTex ("Albedo (RGB)", 2D) = "white" {}
_Glossiness ("Smoothness", Range(0,1)) = 0.5
_Metallic ("Metallic", Range(0,1)) = 0.0
}

Tags { "RenderType"="Opaque" }

LOD

VertexLit及其系列 = 100
Decal, Reflective VertexLit = 150
Diffuse = 200
//Diffuse Detail, Reflective Bumped Unlit, Reflective
Bumped VertexLit = 250
Bumped, Specular = 300
Bumped Specular = 400
Parallax = 500
Parallax Specular = 600

Blend SrcAlpha OneMinusSrcAlpha  //Alpha blending
Blend One One  //Additive
Blend One OneMinusDstColor// Soft Additive
Blend  DstColor Zero  //Multiplicative
Blend DstColor SrcColor  //2x Multiplicative

sampler2D _MainTex;

unity自定义的顶点输入结构体，当然我们也可以自定义
struct appdata_base {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};
struct appdata_tan {
float4 vertex : POSITION;
float4 tangent : TANGENT;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};
struct appdata_full {
float4 vertex : POSITION;
float4 tangent : TANGENT;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
float4 texcoord1 : TEXCOORD1;
fixed4 color : COLOR;

#if defined(SHADER_API_XBOX360)
half4 texcoord2 : TEXCOORD2;
half4 texcoord3 : TEXCOORD3;
half4 texcoord4 : TEXCOORD4;
half4 texcoord5 : TEXCOORD5;
#endif

};

//顶点输出结构体
struct v2f
{
float2 uv : TEXCOORD0;
float3 worldLightDir:TEXCOORD1;
float3 worldViewDir:TEXCOORD2;
float3 worldNormal:TEXCOORD3;
float4 vertex : SV_POSITION;
};

half _Glossiness;

half _Metallic;
fixed4 _Color;

v2f vert (appdata_full v)
{
v2f o;
o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
//计算世界空间中的光的方向
o.worldLightDir = normalize(UnityWorldSpaceLightDir(v.vertex));
//计算世界空间中的视角的方向
o.worldViewDir = normalize(UnityWorldSpaceViewDir(v.vertex));
//计算世界空间中的法线的方向
o.worldNormal = normalize(mul(_World2Object,v.normal));
return o;
}

fixed4 frag (v2f i) : SV_Target
{
//从顶点传过来的各种方向
float3 worldLightDir = i.worldLightDir;
float3 worldViewDir = i.worldViewDir;
float3 worldNormal = i.worldNormal;
//环境光
float3 ambient = UNITY_LIGHTMODEL_AMBIENT.rgb;
//纹理采样，获取材质颜色
fixed4 albedo = tex2D(_MainTex, i.uv);
//获取漫反射系数
float diff = max(0,dot(worldLightDir,worldNormal));
//半漫反射系数
diff = diff * 0.5 + 0.5;
//漫反射颜色计算
float diffcolor = _LightColor0.rgb * diff * albedo.rgb;
//半角向量
float3 halfdir = normalize( worldLightDir + worldViewDir);
//高光系数
float spec = pow(max(0,dot( halfdir,worldNormal)),_Gloss);
//高光颜色
float3 speccolor = _LightColor0.rgb * _Specular.rgb * spec;
//最终颜色
float4 color = float4((diffcolor + speccolor + ambient) * _Color,1.0);
//输出
return color;
}
ENDCG                                                                      //结束标记，表明从这里结束CG程序
}
FallBack "Diffuse"                                                              //FallBack "name"   回滚到指定shader
//FallBack Off     没有回滚
}