Cg入门21：Fragment shader - 2D纹理采样

Shader "Sbin/TexShader"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_U("U",range(-0001,0.001)) = 0
		_V("V",range(0,1)) = 0
	}
	SubShader
	{
		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			sampler2D _MainTex;
			float _U;
			float _V;

			struct v2f{
				float4 pos:POSITION;
				float2 uv:TEXCOORD0;
			};

			v2f vert (appdata_base v)
			{
				v2f o;
				o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
				o.uv = v.texcoord.xy;
				return o;
			}

			fixed4 frag (v2f v) : COLOR
			{
				fixed4 col = tex2D(_MainTex, v.uv);//第一个参数：纹理，第二个参数UV向量
				return col;
			}
			ENDCG
		}
	}
}