Shader--the shadow implementation of the mobile side

There are many ways to implement the shadow on the mobile side, which is realized by shader. The principle is relatively simple,

Flatten the model along the y direction and then extend the ZX in one direction, equivalent to rendering the model more than once, and a DC

But it's quite provincial compared to the expensive real-time shadows.

The shadow is the equivalent of a plane, and even if it is, it can accommodate a slightly undulating terrain.

The code is as follows:

Shader"Game-x/planarshadow"{Properties {_strength ("Strength", Range (0.1,Ten)) =3_maintex ("Base (RGB)", 2D) =" White"{} _projplane ("_projplane", Float) =0_lightdir ("_lightdir", Vector) = (0,0.707,0.707)} subshader {Tags {"Queue"="geometry+1" "Rendertype"="Opaque"} pass {Tags {"Lightmode"="Forwardbase"} Blend one srcalpha zwrite off ZTest off Cgprogram #pragmaVertex vert#pragmaFragment Frag#pragmaMulti_compile _blend_alpha_on _blend_alpha_off#pragmaMulti_compile _blend_additive_on _blend_additive_off#include"Unitycg.cginc"#include"Lighting.cginc"            structVsin {float4 vertex:position; #ifDefined (_blend_alpha_on) | | Defined (_blend_additive_on)FLOAT2 texcoord:texcoord0; #endif            }; structvsout {float4 wpos:sv_position; #ifDefined (_blend_alpha_on) | | Defined (_blend_additive_on)FLOAT2 texcoord:texcoord0; #endif             }; float_strength; float_projplane;            FLOAT3 _lightdir;            Sampler2d _maintex;                        FLOAT4 _maintex_st;                Vsout Vert (Vsin in) {vsout o; FLOAT4 WP=Mul (Unity_objecttoworld, In.vertex); if(Wp.y <_projplane) wp.y=_projplane; Wp.xz= Wp.xz-((WP.Y-_projplane)/_lightdir.y) *_lightdir.xz; WP.Y=_projplane; O.wpos=Mul (UNITY_MATRIX_VP, WP); #ifDefined (_blend_alpha_on) | | Defined (_blend_additive_on)O.texcoord=Transform_tex (In.texcoord, _maintex); #endif                returno; } float4 Frag (Vsout in): COLOR {float4 ambient= Unity_lightmodel_ambient *2; floatK = (AMBIENT.R + ambient.g + ambient.b)/_strength; #ifdef _blend_alpha_onfloatA =tex2d (_maintex, In.texcoord). A; K= Lerp (1, K, a); if(A <=0) Clip (-1); #endif#ifdef _blend_additive_on FLOAT3 t=tex2d (_maintex, In.texcoord). RGB; floatQ = (T.R + t.g + t.b)/3; if(Q <=0) Clip (-1); #endif                returnFLOAT4 (0,0,0, K); } ENDCG} }}

Shader--the shadow implementation of the mobile side