主角场景效果：人物阴影

基本原理：使用Projector和Camera结合实现的动态阴影，使用Camera渲染出一张模型轮廓图，再用Projector投射到场景的接收物体上。

思路：

1、创建一个GameObject用来挂载Projector和Camera。

2、生成一张RenderTexture贴图，命名为mShadowRT。

3、创建一个单独渲染主角轮廓的相机，挂在GameObject上，为相机替换一个简单shader(ShadowCaster)，只渲染模型的轮廓图，渲染的结果targetTexture 保存到mShadowRT中。

4、创建一个投射器Projector，挂在GameObject上，为Projector设置一个投影shader(ShadowReceive)，该shader的材质贴图使用保存有相机渲染的mShadowRT。

5、GameObject随主角位置的移动而更新。

两个Shader：

ShadowCaster：

 1 Shader "xj/ModelEffect/ShadowReceive" 
 2 {
 3     Properties {
 4         _ShadowTex ("ShadowTex", 2D) = "gray" {}
 5         _bulerWidth ("BulerWidth", float) = 1
 6         _shadowfactor ("Shadowfactor", Range(0,1)) = 0.3
 7         _ShadowMask ("ShadowMask",2D) = "white"{}
 8     }
 9     SubShader {
10         Tags { "Queue"="AlphaTest+1" }
11         Pass {
12             ZWrite Off
13             ColorMask RGB
14             Blend DstColor Zero
15             Offset -1, -1
16 
17             CGPROGRAM
18             #pragma vertex vert
19             #pragma fragment frag
20             #include "UnityCG.cginc"
21 
22             struct v2f {
23                 float4 pos:POSITION;
24                 float4 sproj:TEXCOORD0;
25             };
26 
27             float4x4 _Projector;
28             sampler2D _ShadowTex;
29             sampler2D _ShadowMask;
30             uniform half4 _ShadowTex_TexelSize;
31             float _bulerWidth;
32             float _shadowfactor;
33 
34             v2f vert(float4 vertex:POSITION){
35                 v2f o;
36                 o.pos = mul(UNITY_MATRIX_MVP,vertex);
37                 o.sproj = mul(_Projector, vertex);
38                 return o;
39             }
40 
41             float4 frag(v2f i):COLOR{
42                 
43                 half4 shadowCol = tex2Dproj(_ShadowTex, UNITY_PROJ_COORD(i.sproj));
44                 half maskCol = tex2Dproj(_ShadowMask, UNITY_PROJ_COORD(i.sproj)).r;
45                 half a = (shadowCol * maskCol).a;
46                 if(a > 0)
47                 {
48                     return  float4(1,1,1,1) * (1 - _shadowfactor * a);
49                 }
50                 else
51                 {
52                     return float4(1,1,1,1) ;
53                 }
54             }
55 
56             ENDCG
57         }
58     } 
59     FallBack "Diffuse"
60 }

View Code

ShadowReceive：

 1 Shader "xj/ModelEffect/ShadowCaster"
 2 {
 3     Properties
 4     {
 5         _MainTex ("Texture", 2D) = "white" {}
 6         _TintColor ("Tint Color", Color) = (0.5,0.5,0.5,0.5)
 7         _AlphaCutoff ("Cutoff", float) = 0.5
 8     }
 9     Subshader 
10     {
11         Tags { "RenderType"="Opaque" "Queue"="Geometry"}
12         Pass {
13             Lighting Off Fog { Mode off } 
14             SetTexture [_MainTex] {
15                 constantColor (1,1,1,1)
16                 combine constant
17             }
18         }    
19     }
20     Subshader 
21     {
22         Tags { "RenderType"="TransparentCutout" "Queue"="AlphaTest"}
23         Pass {
24             Lighting Off Fog { Mode off } 
25             AlphaTest Greater [_AlphaCutoff]
26             Color [_TintColor]
27             SetTexture [_MainTex] {
28                 constantColor (1,1,1,1)
29                 combine constant, previous * texture
30             }
31         }    
32     }
33     Subshader 
34     {
35         Tags { "RenderType"="TransparentAlphaBlended" "Queue"="Transparent"}
36         Pass {
37             Lighting Off Fog { Mode off } 
38             ZWrite Off
39             Blend SrcAlpha OneMinusSrcAlpha
40             Color [_TintColor]
41             SetTexture [_MainTex] {
42                 constantColor (1,1,1,1)
43                 combine constant, previous * texture
44             }
45         }    
46     }
47     Subshader 
48     {
49         Tags { "RenderType"="TransparentAlphaAdditve" "Queue"="Transparent"}
50         Pass {
51             Lighting Off Fog { Mode off } 
52             ZWrite Off
53             Blend SrcAlpha One
54             Color [_TintColor]
55             SetTexture [_MainTex] {
56                 constantColor (1,1,1,1)
57                 combine constant, previous * texture
58             }
59         }    
60     }
61 }

View Code

效果图：