为什么此着色器在作为字符串提供给 Material 构造函数时会产生解析错误？

Question

我写了以下Shader:

Shader "Custom/SimpleShader" {
    Properties {
        _MainTex("Base (RGB)", 2D) = "white" { }
    }

    SubShader {
        Pass {
            ZTest Always
            Cull Off
            ZWrite Off

/* LINE 16*/CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"

            struct v2f {
                float4 pos  : SV_POSITION;
                float2 uv   : TEXCOORD0;
                float2 uvb  : TEXCOORD1;
            };

            uniform sampler2D _MainTex;
            uniform sampler2D _Texture0;
            uniform fixed _Alpha0;

            v2f vert(appdata_img v)
            {
                v2f o;
                o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                o.uv = MultiplyUV(UNITY_MATRIX_TEXTURE0, v.texcoord);
                o.uvb = MultiplyUV(UNITY_MATRIX_TEXTURE0, v.texcoord);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                fixed4 col = tex2D(_MainTex, i.uv);
                col.rgb += (tex2D(_Texture0, i.uvb).rgb * _Alpha0);
                return col;
            }

            ENDCG
        }
    }
    Fallback off
}

Unity 告诉我第 16 行有一个 "Syntax Error"（见标记）。当我将此文本放入 string 并将此 string 提供给 Material(string contents) 构造函数时，就会发生这种情况。但是，当我将文本放入 .shader 文件并以正常方式导入时，着色器被接受并且不会产生错误。

Answer 1

This documentation 关于 Material(string contents) 构造函数（或者说它的 JavaScript 构造函数）说：

[...] Creating materials this way supports only simple shaders (fixed function ones). If you need a surface shader, or vertex/pixel shaders, you'll need to create shader asset in the editor and use that.

因此，答案是 fragment- and/or vertex-shaders 不支持这种方式。

为什么此着色器在作为字符串提供给 Material 构造函数时会产生解析错误？

Why is this Shader producing a parse error when given as string to the Material constructor?

shader

cg

unity3d

vertex-shader

fragment-shader