Shader刚入门，记录一下刚玩出来的全息投影效果。
先看原模型：
说到全息投影，最先想到的就是一条条扫描线，在模型上随着投影方向逐层扫描。
原理也比较简单，准备一张扫描采样图，在片元着色器中根据模型的x坐标采样再加上时间变量即可。
// 扫描线流动动画
fixed scroll = _Speed * _Time;
fixed4 col = tex2D(_MainTex,i.uv);
fixed scrollProject =abs(i.objectPos.x scroll - round(i.objectPos.x scroll));
fixed4 cybercol = tex2D(_CyberTex, scrollProject);
fixed alpha = 1;
if(cybercol.r cybercol.g cybercol.b < 1){
alpha = 0;
col = max(cybercol,col);
} 
实现了非常粗暴的扫描线。
再计算视角与法线的点乘，加上边缘光效果。
代码语言：javascript复制//边缘光
fixed edge = pow(i.VdotN, 1) / _Range;
edge = edge > _OutlineThred ? 1 : edge;
edge = 1 - edge;
//小于thred的部分视为边缘
fixed4 edgeCol = pow(edge, 0.1) * fixed4(_EdgeColor.rgb fixed3(0.3,0.3,0.5) * (sin(_Time.y * 3) 1)*0.5,edge);
//边缘颜色处理
col = col*(1-edgeCol.a) edgeCol*edgeCol.a;
最后加上两个PASS（其实用一个做法线外扩也可以）做出残影效果，每个pass的算法和前面的基本一致。
完整代码如下：
代码语言：javascript复制Shader "Cyber/cyberProjection"
{
Properties
{
_CyberTex ("Cyber Texture", 2D) = "white" {}
_CyberTexBack ("Cyber Texture Back", 2D) = "white" {}
_MainTex ("Main Texture", 2D) = "white" {}
[HDR]_EdgeColor("Edge Color", Color) = (1,1,1,1)
[HDR]_OutsideColor("Outside Color", Color) = (1,1,1,1)
_Speed("Speed", Range(-5,5)) = 1
_OutlineThred("OutlineThred", Range(0,1)) = 0.5
_Range("Range", Range(0,2)) = 1
_Size("Size", Range(0,1)) = 0.5
}
SubShader
{
Tags { "RenderType"="Transparent" "Queue" = "Transparent" "IgnoreProjector" = "True" "ForceNoShadowCasting" = "True"}
LOD 100
Blend SrcAlpha OneMinusSrcAlpha
Pass
{
// Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
fixed3 normal : NORMAL;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
float4 objectPos : TEXCOORD1;
float4 VdotN : TEXCOORD2;
UNITY_FOG_COORDS(3)
};
sampler2D _CyberTex;
float4 _CyberTex_ST;
float4 _CyberTex_TexelSize;
sampler2D _MainTex;
float4 _MainTex_ST;
// fixed4 _MainColor;
fixed4 _EdgeColor;
fixed _Speed;
fixed _Offset;
float _Range;
float _OutlineThred;
v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _CyberTex);
o.objectPos = v.vertex;
float3 viewDir = normalize(
mul(unity_WorldToObject,
float4(_WorldSpaceCameraPos.xyz, 1)).xyz - v.vertex);
o.VdotN = dot(normalize(viewDir),v.normal);
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
// 流动动画
fixed scroll = _Speed * _Time;
fixed4 col = tex2D(_MainTex,i.uv);
fixed scrollProject =abs(i.objectPos.x scroll - round(i.objectPos.x scroll));
fixed4 cybercol = tex2D(_CyberTex, scrollProject);
fixed alpha = 1;
alpha -= i.objectPos.x;
if(cybercol.r cybercol.g cybercol.b < 1){
alpha = 0;
col = max(cybercol,col);
}
//边缘光
fixed edge = pow(i.VdotN, 1) / _Range;
edge = edge > _OutlineThred ? 1 : edge;
edge = 1 - edge;
//小于thred的部分视为边缘
fixed4 edgeCol = pow(edge, 0.1) * fixed4(_EdgeColor.rgb fixed3(0.3,0.3,0.5) * (sin(_Time.y * 3) 1)*0.5,edge);
//边缘颜色处理
col = col*(1-edgeCol.a) edgeCol*edgeCol.a;
UNITY_APPLY_FOG(i.fogCoord, col);
return fixed4(col.rgb,alpha);
}
ENDCG
}
Pass
{
// Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
float4 objectPos : TEXCOORD1;
float4 VdotN : TEXCOORD2;
UNITY_FOG_COORDS(3)
};
sampler2D _CyberTexBack;
float4 _CyberTexBack_ST;
float4 _CyberTexBack_TexelSize;
sampler2D _MainTex;
float4 _MainTex_ST;
float4 _OutsideColor;
// fixed4 _MainColor;
fixed _Speed;
fixed _Offset;
fixed _Size;
v2f vert (appdata v)
{
v2f o;
v.vertex.x -= _Size;
v.vertex.y -= _Size;
v.vertex.z -= _Size;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _CyberTexBack);
o.objectPos = v.vertex;
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
fixed scroll = _Speed * _Time / 2;
fixed4 col = tex2D(_MainTex,i.uv);
fixed scrollProject =abs(i.objectPos.x scroll - round(i.objectPos.x scroll));
fixed4 cybercol = tex2D(_CyberTexBack, scrollProject);
fixed alpha = 1;
if(cybercol.r cybercol.g cybercol.b < 1){
alpha = 0;
col = min(cybercol,col);
}
col *= _OutsideColor;
UNITY_APPLY_FOG(i.fogCoord, col);
return fixed4(col.rgb,alpha*0.5);
}
ENDCG
}
Pass
{
// Cull Off
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
// make fog work
#pragma multi_compile_fog
#include "UnityCG.cginc"
struct appdata
{
float4 vertex : POSITION;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
float4 objectPos : TEXCOORD1;
float4 VdotN : TEXCOORD2;
UNITY_FOG_COORDS(3)
};
sampler2D _CyberTexBack;
float4 _CyberTexBack_ST;
float4 _CyberTexBack_TexelSize;
float4 _OutsideColor;
sampler2D _MainTex;
float4 _MainTex_ST;
// fixed4 _MainColor;
fixed _Speed;
fixed _Offset;
fixed _Size;
v2f vert (appdata v)
{
v2f o;
v.vertex.x = _Size;
v.vertex.y = _Size;
v.vertex.z = _Size;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = TRANSFORM_TEX(v.uv, _CyberTexBack);
o.objectPos = v.vertex;
UNITY_TRANSFER_FOG(o,o.vertex);
return o;
}
fixed4 frag (v2f i) : SV_Target
{
fixed scroll = _Speed * _Time * 2;
fixed4 col = tex2D(_MainTex,i.uv);
fixed scrollProject =abs(i.objectPos.x scroll - round(i.objectPos.x scroll));
fixed4 cybercol = tex2D(_CyberTexBack, scrollProject);
fixed alpha = 1;
if(cybercol.r cybercol.g cybercol.b < 1){
alpha = 0;
col = min(cybercol,col);
}
col *= _OutsideColor;
UNITY_APPLY_FOG(i.fogCoord, col);
return fixed4(col.rgb,alpha*0.5);
}
ENDCG
}
}
}
