基于SDF的光照效果
好久没写博客了，怠惰了，就当爬了一步
效果
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Shader "Unlit/SDF"
{
Properties
{
_Color ("Color", Color) = (1,1,1,1)
_MainTex ("Texture", 2D) = "white" {}
_SdfTex ("SdfTex", 2D) = "white" {}
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 100
Pass
{
Tags { "LightMode"="ForwardBase" }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
};
float4 _Color;
sampler2D _MainTex;
sampler2D _SdfTex;
float4 _MainTex_ST;
float4 _SdfTex_ST;
v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _MainTex);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
// sample the texture
fixed4 col = tex2D(_MainTex, i.uv);
//SDF
float4 Left_tex = tex2D(_SdfTex, i.uv);
float4 Right_tex = tex2D(_SdfTex, float2(1-i.uv.x, i.uv.y));
float3 lightDir = _WorldSpaceLightPos0.xyz; //光线入射向量
float3 RightSide = UnityObjectToWorldDir(float4(1.0,0.0,0.0,1.0)); //世界空间下右向量
float is_right = dot(lightDir.x, RightSide.x); //光线是否在右边？
float4 shadow = is_right > 0 ? Right_tex : Left_tex; //采样的阈值
float3 forward = UnityObjectToWorldDir(float4(0.0,0.0,1.0,1.0));
float reflect_val = -0.5 * dot(forward, lightDir) + 0.5; //计算得到的阈值
float is_shadow = shadow < reflect_val ? 1:0; //比较两者，判断是否在阴影内
float4 halfShadow = 0.5 * is_shadow + 0.5;
return col * _Color* halfShadow;
}
ENDCG
}
}
}