# 【三平面映射】
可以解决UV接缝不连续和缩放导致的拉伸显示异常。
下面是未使用（红色组）和使用了（蓝色组）的两组效果对比：
# Shader实现
Shader "vp/Triplanar"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
_falloff("FallOff",float) = 1
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 100
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct v2f
{
float4 pos : SV_POSITION;
float3 worldPos :TEXCOORD0;
float3 worldNormal:TEXCOORD1;
};
sampler2D _MainTex;
float4 _MainTex_ST;
float _falloff;
inline float4 TriplanarSampling44(sampler2D topTexMap, float3 worldPos, float3 worldNormal, float falloff, float2 tiling)
{
float3 projNormal = (pow(abs(worldNormal), falloff));
projNormal /= (projNormal.x + projNormal.y + projNormal.z) + 0.00001;
float3 nsign = sign(worldNormal);
half4 xNorm; half4 yNorm; half4 zNorm;
xNorm = tex2D(topTexMap, tiling * worldPos.zy * float2(nsign.x, 1.0));
yNorm = tex2D(topTexMap, tiling * worldPos.xz * float2(nsign.y, 1.0));
zNorm = tex2D(topTexMap, tiling * worldPos.xy * float2(-nsign.z, 1.0));
return xNorm * projNormal.x + yNorm * projNormal.y + zNorm * projNormal.z;
}
v2f vert (appdata v)
{
v2f o;
o.pos = UnityObjectToClipPos(v.vertex);
o.worldPos = mul(v.vertex, unity_ObjectToWorld);
o.worldNormal = mul(unity_WorldToObject, v.normal);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
half4 col = TriplanarSampling44(_MainTex,i.worldPos,i.worldNormal,_falloff,_MainTex_ST.xy);
return col;
}
ENDCG
}
}
}