最近几个月在慢慢学习Shader编程，只看书本上的代码不太记得住，打算找一些网上的例子动手实现一下加深印象。
这是一个边缘高亮的效果，原理非常简单，设x是视点到物体表面要渲染的某点的连线，y是该点的法线（需要在同一坐标系中），判断x与y的夹角（利用点乘符号判断），如果x与y垂直或接近垂直，就可以判定该点位于边界上。具体实现在Fragment Shader中进行。(Line 69-74)
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Shader "TestShader/Margin" {
Properties{
_Color("Color Tint", Color) = (1, 1, 1, 1)
_MarginColor("Margin Color", Color) = (1, 1, 1, 1)
_MainTex("Main Tex", 2D) = "white" {}
_AlphaScale("Alpha Scale", Range(0, 1)) = 1
_Para1("Para 1", Range(0, 0.5)) = 0.3
}
SubShader{
Tags {"Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent"}
// Extra pass that renders to depth buffer only
Pass {
ZWrite On
// "ColorMask RGB | A | 0 |"
// "ColorMask 0" means this pass DO NOT write color buffer
ColorMask 0
}
Pass {
Tags { "LightMode" = "ForwardBase" }
ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "Lighting.cginc"
fixed4 _Color;
fixed4 _MarginColor;
sampler2D _MainTex;
float4 _MainTex_ST;
fixed _AlphaScale;
fixed _Para1;
struct a2v {
float4 vertex : POSITION;
float3 normal : NORMAL;
float4 texcoord : TEXCOORD0;
};
struct v2f {
float4 pos : SV_POSITION;
float3 worldNormal : TEXCOORD0;
float3 worldPos : TEXCOORD1;
float2 uv : TEXCOORD2;
};
v2f vert(a2v 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);
return o;
}
fixed4 frag(v2f i) : SV_Target {
fixed3 worldNormal = normalize(i.worldNormal);
fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));
fixed4 texColor = tex2D(_MainTex, i.uv);
fixed3 albedo = texColor.rgb * _Color.rgb;
fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
fixed3 diffuse = _LightColor0.rgb * albedo;
// 计算表面法线与视线夹角
float val = dot(normalize(UnityWorldSpaceViewDir(i.worldPos)), worldNormal);
if (val < _Para1)
return fixed4(_MarginColor.rgb, _AlphaScale);
else
return fixed4(ambient + diffuse, _AlphaScale);
}
ENDCG
}
}
FallBack "Transparent/VertexLit"
}
