Unity Shader学习笔记 - 用UV动画实现沙滩上的泡沫

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

//岸边浪花泡沫
//CloudLty 2016-9-6
Shader "Custom/foams2"
{
Properties//标记所以外部变量，让该变量按标记显示在编辑器中
{
_TintColor      ("Tint Color (RGBA)", Color) = (1,1,1,1)
_MainTex        ("Texture (RGB)", 2D) = "white" {}
_Mask           ("Mask", 2D) = "white" {}
_AlphaDelay     ("Alpha Delay", Range(-1,1)) = 0
_Speed          ("Time Scale", Range(0,1)) = 0.25
_WaveRange      ("Wave Range", Range(-1,1)) = 0.6
_Layer1OffsetX  ("Layer1 Offset X", Range(-2,2)) = 0
_Layer2OffsetX  ("Layer2 Offset X", Range(-2,2)) = 0
_Layer3OffsetX  ("Layer3 Offset X", Range(-2,2)) = 0
_Layer1OffsetY  ("Layer1 Offset Y", Range(-2,2)) = 0
_Layer2OffsetY  ("Layer2 Offset Y", Range(-2,2)) = 0
_Layer3OffsetY  ("Layer3 Offset Y",Range(-2,2)) = 0

}
SubShader
{
Tags
{
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
LOD 100

Pass
{
ZWrite off
Blend srcAlpha OneMinusSrcAlpha
CGPROGRAM
#pragma vertex vert     //顶点着色器 类似于宏定义，告诉Unity这个函数名是顶点做色器函数
#pragma fragment frag   //片段着色器

#include "UnityCG.cginc" //类似头文件？主要是Untiy提供的一些常用函数 貌似不写编译时也会自动包含进来

//顶点着色器输入结构体
struct appdata
{
float4 vertex : POSITION;   //POSITION输入语义，Unity将顶点坐标提交于此变量
float4 uv : TEXCOORD0;      //TEXCOORD0，Unity将模型第一套UV提交于此变量
};

//顶点着色器输出结构体 （反正会给片段做色器使用）
struct v2f
{
UNITY_FOG_COORDS(1)
float4 vertex : SV_POSITION;//输出语义
float4 uv1 : TEXCOORD0;
float4 uv2 : TEXCOORD1;
float4 uv3 : TEXCOORD2;
float2 uv4 : TEXCOORD3;
};

//外部变量声明
uniform sampler2D   _MainTex;
uniform float4      _MainTex_ST;
uniform sampler2D   _Mask;
uniform float4      _Mask_ST;
uniform half4       _TintColor;
uniform float       _AlphaDelay;
uniform float       _Speed;
uniform float       _WaveRange;
uniform float       _Layer1OffsetX;
uniform float       _Layer2OffsetX;
uniform float       _Layer3OffsetX;
uniform float       _Layer1OffsetY;
uniform float       _Layer2OffsetY;
uniform float       _Layer3OffsetY;

//UV动画函数
float2 DelayOffsetUV(float2 uv, float offset, float offset_y)//输入UV 和偏移量（x，y），外部变量控制速度，范围
{
float pi = 3.1415926536f;
float sintime = sin(_Time.y * _Speed * pi + offset * 0.5f * pi);//余弦函数使UV来回移动,
float u = (sintime + 1) * 0.5f * _WaveRange + (1 - _WaveRange);
uv.x += u;
uv.y += offset_y;
return uv;
}

//顶点着色器
v2f vert(appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);

//逐层偏移
float2 inuv = v.uv;
// layer1 uv offset
float2 uv_tex1 = DelayOffsetUV(inuv, _Layer1OffsetX, _Layer1OffsetY);
o.uv1.xy = TRANSFORM_TEX(uv_tex1, _MainTex);

// layer1 uv offset
float2 uv_tex2 = DelayOffsetUV(inuv, _Layer2OffsetX, _Layer2OffsetY);
o.uv1.zw = TRANSFORM_TEX(uv_tex2, _MainTex);

// layer1 uv offset
float2 uv_tex3 = DelayOffsetUV(inuv, _Layer3OffsetX, _Layer3OffsetY);
o.uv2.xy = TRANSFORM_TEX(uv_tex3, _MainTex);

//每一层的Mask（透贴）偏移，偏移量与tex一致，并可以用_AlphaDelay微调
// mask1 uv offset
float2 uv_mask1 = DelayOffsetUV(inuv, _Layer1OffsetX - _AlphaDelay, _Layer1OffsetY);
o.uv2.zw = TRANSFORM_TEX(uv_mask1, _Mask);

// mask2 uv offset
float2 uv_mask2 = DelayOffsetUV(inuv, _Layer2OffsetX - _AlphaDelay, _Layer2OffsetY);
o.uv3.xy = TRANSFORM_TEX(uv_mask2, _Mask);

// mask3 uv offset
float2 uv_mask3 = DelayOffsetUV(inuv, _Layer3OffsetX - _AlphaDelay, _Layer3OffsetY);
o.uv3.zw = TRANSFORM_TEX(uv_mask3, _Mask);

UNITY_TRANSFER_FOG(o,o.vertex);

o.uv4 = inuv;
return o;
}

//获取泡沫逐渐出现，向岸边移动，开始折返并逐渐消失的透明度值
fixed GetDisappearAlpha(float delay)
{
float PI = 3.1415926536f;
float t = _Time.y *_Speed * PI + delay * 0.5* PI + 1.2 * PI;
fixed a = (sin(t)+1)*0.5;
return a*a;
}

//将两层半透明的颜色合并，获取合并后的RGBA
fixed4 TwoColorBlend(fixed4 c1, fixed4 c2)
{
fixed4 c12;
c12.a = c1.a + c2.a - c1.a * c2.a;
c12.rgb = (c1.rgb * c1.a * (1 - c2.a) + c2.rgb * c2.a) / c12.a;
return c12;
}

//片段着色器
fixed4 frag(v2f i) : SV_Target //参数为输入结构体，语义就是输出到什么地方
{
fixed pi = 3.1415926536f;

//get rgb
fixed4 c1 = tex2D(_MainTex, i.uv1.xy);
fixed4 c2 = tex2D(_MainTex, i.uv1.zw);
fixed4 c3 = tex2D(_MainTex, i.uv2.xy);

//get alpha
c1.a = tex2D(_Mask, i.uv2.zw) * GetDisappearAlpha(_Layer1OffsetX);
c2.a = tex2D(_Mask, i.uv3.xy) * GetDisappearAlpha(_Layer2OffsetX);
c3.a = tex2D(_Mask, i.uv3.zw) * GetDisappearAlpha(_Layer3OffsetX);

//layer1 + layer2
fixed4 c12 = TwoColorBlend(c1,c2);
//layer12 + layer3
fixed4 c123 = TwoColorBlend(c12,c3);

return c123 * _TintColor;
}
ENDCG
}
}
}