unityShader模型动态裁剪，动态生长

忘记在哪里找的的shader了，有的我做了简单的修改，有的我只是结合了一下，我会把以转载的方式发出来，以尊重原创开发。

这次的是找到的模型的“裁剪”效果，并不是真正的基于模型的裁剪，并不会影像碰撞等效果，而是基于渲染的裁剪，效果如下：

接下来上代码：

// Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'

//消失效果
//by：puppet_master
//2017.8.11

Shader "SepShader/DissolveEffectX"
{
	Properties{
		_Diffuse("Diffuse", Color) = (1,1,1,1)
		_DissolveColor("Dissolve Color", Color) = (0,0,0,0)
		_MainTex("Base 2D", 2D) = "white"{}
		_ColorFactor("ColorFactor", Range(0,1)) = 0.7//这个值什么时候光圈在最下边呢，当模型比例为1时最下端点到中心点的Y值差
		_DissolveThreshold("DissolveThreshold", Float) = 0
	}

		CGINCLUDE
#include "Lighting.cginc"
		uniform fixed4 _Diffuse;
	uniform fixed4 _DissolveColor;
	uniform sampler2D _MainTex;
	uniform float4 _MainTex_ST;
	uniform float _ColorFactor;
	uniform float _DissolveThreshold;

	struct v2f
	{
		float4 pos : SV_POSITION;
		float3 worldNormal : TEXCOORD0;
		float2 uv : TEXCOORD1;
		float4 objPos : TEXCOORD2;
	};

	v2f vert(appdata_base v)
	{
		v2f o;
		o.pos = UnityObjectToClipPos(v.vertex);
		o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
		o.worldNormal = mul(v.normal, (float3x3)unity_WorldToObject);
		o.objPos = v.vertex;//以模型座标为标准
		//o.objPos = mul(unity_ObjectToWorld, v.vertex);//以世界座标为标准
		return o;
	}

	fixed4 frag(v2f i) : SV_Target
	{
		float factor = i.objPos.z - _DissolveThreshold;//这句话我理解为相对于中心在Y方向上的值减去阈值
	clip(factor);
	//Diffuse + Ambient光照计算
	fixed3 worldNormal = normalize(i.worldNormal);
	fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
	fixed3 lambert = saturate(dot(worldNormal, worldLightDir));
	fixed3 albedo = lambert * _Diffuse.xyz * _LightColor0.xyz + UNITY_LIGHTMODEL_AMBIENT.xyz;
	fixed3 color = tex2D(_MainTex, i.uv).rgb * albedo;
	//等价于下面注释代码的操作
	fixed lerpFactor = saturate(sign(_ColorFactor - factor));
	return lerpFactor * _DissolveColor + (1 - lerpFactor) * fixed4(color, 1);
	/*
	if (factor < _ColorFactor)
	{
	return _DissolveColor;
	}
	return fixed4(color, 1);*/
	}
		ENDCG

		SubShader
	{
		Tags{ "RenderType" = "Opaque" }
			Pass
		{
			//不让模型穿帮，关掉了背面裁剪
			Cull Off
			CGPROGRAM
#pragma vertex vert
#pragma fragment frag	
			ENDCG
		}
	}
	FallBack "Diffuse"
}

注：是基于哪个轴的裁剪需要修改片元着色器中的i.objPos的轴