有没有shader高手？求教一个错误。

shader代码
Shader "Hidden/AVProLiveCamera/CompositeMono8_2_RGBA"
{
Properties
{
_MainTex ("Base (RGB)", 2D) = "white" {}
}
SubShader
{
Pass
{
ZTest Always Cull Off ZWrite Off
Fog { Mode off }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma exclude_renderers flash xbox360 ps3 gles
//#pragma fragmentoption ARB_precision_hint_fastest
#pragma fragmentoption ARB_precision_hint_nicest
#pragma multi_compile SWAP_RED_BLUE_ON SWAP_RED_BLUE_OFF
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
float _TextureWidth;
float4 _MainTex_ST;
float4 _MainTex_TexelSize;
struct v2f {
float4 pos : POSITION;
float4 uv : TEXCOORD0;
};
v2f vert( appdata_img v )
{
v2f o;
o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
o.uv.xy = TRANSFORM_TEX(v.texcoord, _MainTex);
// On D3D when AA is used, the main texture & scene depth texture
// will come out in different vertical orientations.
// So flip sampling of the texture when that is the case (main texture
// texel size will have negative Y).
#if SHADER_API_D3D9
if (_MainTex_TexelSize.y < 0)
{
o.uv.y = 1-o.uv.y;
}
#endif
o.uv.z = v.vertex.x * _TextureWidth * 0.25;
return o;
}
float4 frag (v2f i) : COLOR
{
float4 uv = i.uv;
float4 col = tex2D(_MainTex, uv.xy );
#if defined(SWAP_RED_BLUE_ON)
col = col.bgra;
#endif
float l = col.a;
if (frac(uv.z) < 0.25)
l = col.b;
else if (frac(uv.z) < 0.5)
l = col.g;
else if (frac(uv.z) < 0.75)
l = col.r;
col.rgb = l;
col.a = 1.0;
return col;
}
ENDCG
}
}
FallBack Off
}

错误出现在v2f vert( appdata_img v )方法里。求大神指导。
是不是Unity的5.0的shader写法有什么新的要求吗？

float4 uv : TEXCOORD0;
这个uv是 float4 ，你没有完全初始化
看你的代码，用
float3 uv : TEXCOORD0;

v2f o;
改成
v2f o = （v2f）0;