1.RT+曲面细分的设置
2.雪下瓷砖的细节表现
1.RT+曲面细分
将一个正交摄像机设置在地面以下，将远裁剪面调小（节省深度RT的精度）
正裁剪面在小球或着脚踝以下，能完整的更新RT 避免bug
设置曲面细分tessellate:tessFixed #pragma target 4.6
在vertex shader中变形顶点 (测试，不能进行额外数据的插值)
我这里做的省事了，把RT与平面完全对齐，直接用模型的uv来读取 RT的UV
不然需要在shader中做矩阵变换 读取辅助摄像机对应的RT数据
float4 tessFixed(){
return _Tess;
}
void vert(inout appdata v)
{
float d=tex2Dlod(_DispTex,float4(1-v.texcoord.x , v.texcoord.y , 0 , 0)).r * _Displacement;
v.vertex.xyz -= normalize(v.normal)*d;
}
2.雪下瓷砖的细节表现
1.区分哪里表现雪 哪里表现瓷砖
modelPos是雪最高点的世界坐标高度，建模时，确保模型坐标轴点在平面上
float4 modelPos = float4(0,0,0,1);
float snowHeight=mul(unity_ObjectToWorld,modelPos).y;
float low = snowHeight - IN.worldPos.y;
float mask = low/_Displacement;
mask = smoothstep(0.85,0.95,mask);
fixed3 finalCol = lerp(snowCol,tileCol,mask);
2.对比度调节，模拟表面的薄雪
fixed3 tileCol = tex2D(_MainTex, IN.uv_MainTex).xyz * _Color;
tileCol = lerp(float3(0.5,0.5,0.5),tileCol,_Saturation);
3.模拟砖缝中的雪
在切线空间下，dot（法线，float3（0，0，1）； 得到砖缝
再用一个noise贴图在消除所有砖缝都藏积雪的感觉
//color
fixed3 snowCol = fixed3(0.8,0.8,0.8);
//砖的颜色及调节饱和度
fixed3 tileCol = tex2D(_MainTex, IN.uv_MainTex).xyz * _Color;
tileCol = lerp(float3(0.5,0.5,0.5),tileCol,_Saturation);
float3 normal = UnpackScaleNormal(tex2D(_NormalMap , IN.uv_MainTex),_BumpScale);
//在切线空间计算 法线与z轴夹角
float tileSnow = dot(normal,float3(0,0,1));
//噪声图使得砖缝中的雪不全
float detailMask=tex2D(_MaskMap,IN.uv_MaskMap).x;
tileSnow = clamp(tileSnow + detailMask , 0 , 1);
tileSnow = smoothstep(0.2,0.4,tileSnow);
tileCol = lerp(snowCol,tileCol,tileSnow); //得到非雪的color
shader
Shader "Strees/Snowtile"
{
Properties
{
_Color ("Color", Color) = (1,1,1,1)
_MainTex ("Albedo (RGB)", 2D) = "white" {}
_Saturation("Saturation",Range(0,2))=1.0
_DispTex("Disp Texture",2D)="gray"{}
_Tess("Tessellation",Range(1,32))=4
_Displacement("Displacement",Range(0,1))=0.3
_NormalMap("NormalMap",2D)="bump"{}
_BumpScale("BumpScale",float)=1
_MaskMap("MaskMap",2D)="white"{}
_Glossiness ("Smoothness", Range(0,1)) = 0.5
_Metallic ("Metallic", Range(0,1)) = 0.0
}
SubShader
{
Tags { "RenderType"="Opaque" }
LOD 200
CGPROGRAM
#pragma surface surf Standard addshadow fullforwardshadows vertex:vert tessellate:tessFixed nolightmap
#pragma target 4.6
struct appdata{
float4 vertex:POSITION;
float4 tangent:TANGENT;
float3 normal:NORMAL;
float2 texcoord:TEXCOORD;
};
sampler2D _MainTex;
sampler2D _DispTex;
sampler2D _NormalMap;
sampler2D _MaskMap;
struct Input
{
float2 uv_MainTex;
float3 worldPos;
float2 uv_MaskMap;
};
float _Saturation;
half _Glossiness;
half _Metallic;
fixed4 _Color;
float _Tess;
float _Displacement;
float _BumpScale;
//曲面细分
float4 tessFixed(){
return _Tess;
}
void vert(inout appdata v)
{
float d=tex2Dlod(_DispTex,float4(1-v.texcoord.x , v.texcoord.y , 0 , 0)).r * _Displacement;
v.vertex.xyz -= normalize(v.normal)*d;
}
UNITY_INSTANCING_BUFFER_START(Props)
UNITY_INSTANCING_BUFFER_END(Props)
void surf (Input IN, inout SurfaceOutputStandard o)
{
//color
fixed3 snowCol = fixed3(0.8,0.8,0.8);
//砖的颜色及调节饱和度
fixed3 tileCol = tex2D(_MainTex, IN.uv_MainTex).xyz * _Color;
tileCol = lerp(float3(0.5,0.5,0.5),tileCol,_Saturation);
//读取法线
float3 normal = UnpackScaleNormal(tex2D(_NormalMap , IN.uv_MainTex),_BumpScale);
//在切线空间计算 法线与z轴夹角
float tileSnow = dot(normal,float3(0,0,1));
//噪声图使得砖缝中的雪不全
float detailMask=tex2D(_MaskMap,IN.uv_MaskMap).x;
tileSnow = clamp(tileSnow + detailMask , 0 , 1);
tileSnow = smoothstep(0.2,0.4,tileSnow);
tileCol = lerp(snowCol,tileCol,tileSnow); //得到非雪的color
//data
//得到模型z轴零点的世界坐标
float4 modelPos = float4(0,0,0,1);
float snowHeight=mul(unity_ObjectToWorld,modelPos).y;
float low = snowHeight - IN.worldPos.y;
float mask = low/_Displacement;
mask = smoothstep(0.85,0.95,mask);
fixed3 finalCol = lerp(snowCol,tileCol,mask);
//fianlNormal
float3 normal2 = float3(0,0,1);
float3 finalNormal=lerp(normal2,normal,mask);
o.Albedo = finalCol;
o.Normal = finalNormal;
o.Metallic = _Metallic;
o.Smoothness = _Glossiness;
o.Alpha = 1.0;
}
ENDCG
}
FallBack "Diffuse"
}
