shader内置函数:GLSL到UNITY对应关系

#ifndef GlslToHlsl
#define GlslToHlsl
#define vec2 float2  
#define vec3 float3  
#define vec4 float4  
#define mat2 float2x2  
#define mat3 float3x3  
#define mat4 float4x4  
#define iGlobalTime _Time.y  
#define mod fmod  
#define mix lerp  
#define fract frac  
#define texture2D tex2D  
#define iResolution _ScreenParams  
#define gl_FragCoord ((_iParam.scrPos.xy/_iParam.scrPos.w) * _ScreenParams.xy)  
#define PI2 6.28318530718  
#define pi 3.14159265358979  
#define halfpi (pi * 0.5)  
#define oneoverpi (1.0 / pi)  

#endif