Unity&Shader基础篇-常用函数的使用与案例

一、前言

继前面的系列文章之后，本篇继续讲解Cg的常用函数的使用案例，帮助巩固Cg语言的基础知识。这些函数都可以在Cg的教程里The Cg Tutorial找到示例代码和函数意义。本文讲解几个常用的函数，分别有

1、Step(a,x):如果x<a返回0；如果x>或=a返回1

2、Clamp(x,a,a):如果x<a返回a；如果x>b返回b；如果在a和b之间就返回x

3、smoothstep(min,max,x):返回的值为–2*(( x – min )/( max – min ))³ +3*(( x – min )/( max – min ))²

4、lerp(a,b,f):线性插值函数，返回值为（1-f）*a+b*f

5、三角函数sin、cos

二、常用函数的使用实例

1、Step函数：在Unity中的Shader代码

Shader "Unlit/Chapter5-Step"{Properties{_background("背景色",Color)=(0,0,0,0)}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDEENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"float4 _background;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}// Functionsfixed4 frag(v2f i) : SV_Target{float2 r = 2.0*(i.uv - 0.5);//_ScreenParams是Unity内置的变量float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 pixel = _background.xyz;float edge, variable, ret;//将屏幕划分成五个部分//第一部分if (r.x < -0.6*aspectRatio){variable = r.y;edge = 0.2;if (variable > edge){ret = 1.0;}else{ret = 0;}}else if (r.x < -0.2*aspectRatio){variable = r.y;edge = -0.2;//step(a,x):如果x<a结果返回0，反之返回1ret = step(edge, variable);}else if (r.x < 0.2*aspectRatio){ret = 1.0 - step(0.5, r.y);}else if (r.x < 0.6*aspectRatio){ret = 0.3 + 0.5*step(-0.4, r.y);}else{ret = step(-0.3, r.y) * (1.0 - step(0.2, r.y));}pixel = fixed3(ret, ret, ret);return fixed4(pixel, 1.0);}ENDCG}}}

得到的效果图如图所示：

2、Clamp：在Unity中的代码如下：

Shader "Unlit/Chapter5-Clamp"{Properties{_background("背景色",Color) = (0,0,0,0)}SubShader{// No culling or depthCull Off ZWrite Off ZTest Always// 追加CGINCLUDE//定义宏#define PI 3.14159ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"float4 _background;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}// Functionsfixed4 frag(v2f i) : SV_Target{float2 r = 2.0*(i.uv - 0.5);//_ScreenParams是Unity内置的变量float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 pixel = _background.xyz;float edge, variable, ret;//第一部分if (i.uv.x < 0.25) { // part1ret = i.uv.y;}else if (i.uv.x < 0.5) { // part2float minVal = 0.3;float maxVal = 0.6;variable = i.uv.y;if (variable < minVal) {ret = minVal;}if (variable > minVal && variable < maxVal) {ret = variable;}if (variable > maxVal) {ret = maxVal;}}else if (i.uv.x < 0.75) { // part3float minVal = 0.6;float maxVal = 0.8;variable = i.uv.y;//clam(x,a,b)：x如果小于a返回a，如果大于b返回b，在a~b范围内返回xret = clamp(variable, minVal, maxVal);}else { // part4float y = cos(5.0 * 2.0 * PI *i.uv.y);y = (y + 1.0)*0.5; // map [-1,1] to [0,1]ret = clamp(y, 0.2, 0.8);}pixel = fixed3(ret, ret, ret);return fixed4(pixel, 1.0);}ENDCG}}}

效果图如图所示：

说明：对比1和2的图会明显发现，在使用Clamp处理的时候，边缘的颜色会有渐变的效果。

3、smoothstep：这个脚本只给出片段着色器部分，其他部分同2，代码如下：

fixed4 frag(v2f i) : SV_Target{fixed3 pixel = _background.xyz;float edge, variable, ret;if (i.uv.x < 1.0 / 5.0) { // part1edge = 0.5;ret = step(edge, i.uv.y);}else if (i.uv.x < 2.0 / 5.0) { // part2float edge0 = 0.45;float edge1 = 0.55;float t = (i.uv.y - edge0) / (edge1 - edge0);float t1 = clamp(t, 0.0, 1.0);ret = t1;}else if (i.uv.x < 3.0 / 5.0) { // part3float edge0 = 0.45;float edge1 = 0.55;float t = clamp((i.uv.y - edge0) / (edge1 - edge0), 0.0, 1.0);float t1 = 3.0*t*t - 2.0*t*t*t;ret = t1;}else if (i.uv.x < 4.0 / 5.0) { // part4//smoothstep(min,max,x)：x=-2*((x-min)/(max-min))^3+3*((x-min)/(max-min))^2，当x=min时返回0，当x=max时返回1ret = smoothstep(0.45, 0.55, i.uv.y);}else if (i.uv.x < 5.0 / 5.0) {float edge0 = 0.45;float edge1 = 0.55;float t = clamp((i.uv.y - edge0) / (edge1 - edge0), 0.0, 1.0);float t1 = t*t*t*(t*(t*6.0 - 15.0) + 10.0);ret = t1;}pixel = fixed3(ret, ret, ret);return fixed4(pixel, 1.0);}

得到的效果图如上图所示，这个效果要对比之前的两个，可以发现有明显的过渡效果。当然不是说这个函数就比之前的函数好用，各有千秋，只是在本篇文章中特有的安排而已。

4、lerp函数，Unity中的Shader代码如下：

Shader "Unlit/Chapter5-Lerp"{Properties{_background("背景色",Color) = (0,0,0,0)_col1("颜色1",Color)=(0,0,0,0)_col2("颜色2",Color)=(0,0,0,0)}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDE//定义宏#define PI 3.14159ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"float4 _background;float4 _col1;float4 _col2;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}// Functionsfixed4 frag(v2f i) : SV_Target{fixed3 pixel = _background.xyz;fixed3 ret;if (i.uv.x < 1.0 / 5.0) { // part1float x0 = 0.2;float x1 = 0.7;float m = 0.1;float val = x0 * (1.0 - m) + x1*m;ret = fixed3(val, val, val);}else if (i.uv.x < 2.0 / 5.0) { // part2float x0 = 0.2;float x1 = 0.7;float m = i.uv.y;float val = x0*(1.0 - m) + x1*m;ret = fixed3(val, val, val);}else if (i.uv.x < 3.0 / 5.0) { // part3float x0 = 0.2;float x1 = 0.7;float m = i.uv.y;//lerp(a,b,f)返回(1-f)*a+b*ffloat val = lerp(x0, x1, m);ret = fixed3(val, val, val);}else if (i.uv.x < 4.0 / 5.0) { // part4float m = i.uv.y;ret = lerp(_col1, _col2, m);}else if (i.uv.x < 5.0 / 5.0) {float m = smoothstep(0.5, 0.6, i.uv.y);ret = lerp(_col1, _col2, m);}pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

效果图如图所示：

这个Shader中对lerp函数和smoothstep函数做了对比，其中第三个区域是使用lerp函数的效果，第四个区域是先进行了smoothstep处理在进行lerp处理的效果。

5、lerp函数与直接的颜色加减进行对比：完整的Shader代码如下：

Shader "Unlit/Chapter5-ColorAdd&Substr"{Properties{}SubShader{// No culling or depthCull Off ZWrite Off ZTest Always// 追加CGINCLUDE// 添加画圆盘的方法float disk(float2 r, float2 center, float radius) {float distanceFromCenter = length(r - center);float outsideOfDisk = smoothstep(radius - 0.005, radius + 0.005, distanceFromCenter);float insideOfDisk = 1.0 - outsideOfDisk;return insideOfDisk;}ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}// ANTI-ALIASING WITH SMOOTHSTEPfixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 black = float3(0.0, 0.0, 0.0); // blackfixed3 white = float3(1.0, 1.0, 1.0);fixed3 gray = float3(0.3, 0.3, 0.3);fixed3 col1 = float3(0.216, 0.471, 0.698); // bluefixed3 col2 = float3(1.00, 0.329, 0.298); // redfixed3 col3 = float3(0.867, 0.910, 0.247); // yellowfixed3 ret;fixed3 pixel;float d;//三个部分的画法各有优势//第一部分背景是灰色，简单的覆盖叠加if (i.uv.x < 1.0 / 3.0) { // part1ret = gray;d = disk(r, float2(-1.1, 0.3), 0.4);ret = lerp(ret, col1, d);d = disk(r, float2(-1.3, 0.0), 0.4);ret = lerp(ret, col2, d);d = disk(r, float2(-1.05, -0.3), 0.4);ret = lerp(ret, col3, d);}//第二部分背景是黑色，通过颜色相加来实现else if (i.uv.x < 2.0 / 3.0) { // part2   // Color additionret = black;ret += disk(r, float2(0.1, 0.3), 0.4) * col1;ret += disk(r, float2(-0.1, 0.0), 0.4) * col2;ret += disk(r, float2(0.15, -0.3), 0.4) * col3;}//第三部分背景是白色，通过相减来实现颜色的显示else if (i.uv.x < 3.0 / 3.0) { // part3   // Color substractionret = white;ret -= disk(r, float2(1.1, 0.3), 0.4) * col1;ret -= disk(r, float2(1.05, 0.0), 0.4) * col2;ret -= disk(r, float2(1.35, -0.25), 0.4) * col3;}pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

得到的效果图如图所示：第一部分通过lerp函数来处理颜色重叠的部分，第二、三部分之间通过颜色的加减来处理颜色重叠的部分。

6、三角函数，sin、cos函数：利用正弦余弦函数来做图形的旋转，效果图如图所示：

蓝色的网格和蓝色的矩形、圆盘都是固定的，旋转的是红色的网格以及网格上的矩阵和圆盘，它的shader代码如下：

Shader "Unlit/Chapter6-Rotation"{Properties{_RotateAngle("旋转的角度",Range(0,360))=36}SubShader{// No culling or depthCull Off ZWrite Off ZTest Always// CGINCLUDE#define PI 3.14159// 使用函数来创建网格，返回的值再乘以颜色及得到网格图形float coordinateGrid(float2 r) {float3 axisCol = float3(0.0, 0.0, 1.0);float3 gridCol = float3(0.5, 0.5, 0.5);float ret = 0.0;// 画线const float tickWidth = 0.1;for (float i = -2.0; i<2.0; i += tickWidth) {ret += 1.0 - smoothstep(0.0, 0.008, abs(r.x - i));ret += 1.0 - smoothstep(0.0, 0.008, abs(r.y - i));}// 画坐标轴ret += 1.0 - smoothstep(0.001, 0.015, abs(r.x));ret += 1.0 - smoothstep(0.001, 0.015, abs(r.y));return ret;}// 在圆盘里面的都返回1float disk(float2 r, float2 center, float radius) {return 1.0 - smoothstep(radius - 0.005, radius + 0.005, length(r - center));}// 在长方形里面的都返回1float rectangle(float2 r, float2 bottomLeft, float2 topRight) {float ret;float d = 0.005;ret = smoothstep(bottomLeft.x - d, bottomLeft.x + d, r.x);ret *= smoothstep(bottomLeft.y - d, bottomLeft.y + d, r.y);ret *= 1.0 - smoothstep(topRight.y - d, topRight.y + d, r.y);ret *= 1.0 - smoothstep(topRight.x - d, topRight.x + d, r.x);return ret;}ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform float _RotateAngle;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}//坐标变换：旋转fixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 bgCol = float3(1.0, 1.0, 1.0); // whitefixed3 col1 = float3(0.216, 0.471, 0.698); // bluefixed3 col2 = float3(1.00, 0.329, 0.298); // redfixed3 col3 = float3(0.867, 0.910, 0.247); // yellowfixed3 ret;float2 q;float angle;//angle = 0.2*PI; // 旋转36度angle = _RotateAngle / PI;q.x = cos(angle)*r.x + sin(angle)*r.y;q.y = -sin(angle)*r.x + cos(angle)*r.y;ret = bgCol;// 画出这两个坐标系//底色浅一点为固定轴ret = lerp(ret, col1, coordinateGrid(r)*0.4);//要旋转的坐标轴ret = lerp(ret, col2, coordinateGrid(q));// 画出各种图形//在固定坐标系的图形ret = lerp(ret, col1, disk(r, float2(1.0, 0.0), 0.2));ret = lerp(ret, col1, rectangle(r, float2(-0.8, 0.2), float2(-0.5, 0.4)));//在可旋转坐标系的图形ret = lerp(ret, col2, disk(q, float2(1.0, 0.0), 0.2));ret = lerp(ret, col2, rectangle(q, float2(-0.8, 0.2),float2(-0.5, 0.4)));fixed3 pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

7、使用lerp函数来进行缩放，效果图所示：同样，蓝色部分是固定的，红色部分是缩放的的对象。

缩放的Shader的代码如下：

Shader "Unlit/Chapter6-Scale"{Properties{_ScaleValue("缩放因子",Range(0.1,10))=1}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDE#define PI 3.14159// 使用函数来创建网格，返回的值再乘以颜色及得到网格图形float coordinateGrid(float2 r) {float3 axisCol = float3(0.0, 0.0, 1.0);float3 gridCol = float3(0.5, 0.5, 0.5);float ret = 0.0;// 画网格const float tickWidth = 0.1;for (float i = -2.0; i<2.0; i += tickWidth) {ret += 1.0 - smoothstep(0.0, 0.008, abs(r.x - i));ret += 1.0 - smoothstep(0.0, 0.008, abs(r.y - i));}// 画坐标轴ret += 1.0 - smoothstep(0.001, 0.015, abs(r.x));ret += 1.0 - smoothstep(0.001, 0.015, abs(r.y));return ret;}// 在圆盘内的返回1float disk(float2 r, float2 center, float radius) {return 1.0 - smoothstep(radius - 0.005, radius + 0.005, length(r - center));}// 在长方形内的返回1float rectangle(float2 r, float2 bottomLeft, float2 topRight) {float ret;float d = 0.005;ret = smoothstep(bottomLeft.x - d, bottomLeft.x + d, r.x);ret *= smoothstep(bottomLeft.y - d, bottomLeft.y + d, r.y);ret *= 1.0 - smoothstep(topRight.y - d, topRight.y + d, r.y);ret *= 1.0 - smoothstep(topRight.x - d, topRight.x + d, r.x);return ret;}ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform float _ScaleValue;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}//坐标转换：缩放fixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 bgCol = float3(1.0, 1.0, 1.0); // whitefixed3 col1 = float3(0.216, 0.471, 0.698); // bluefixed3 col2 = float3(1.00, 0.329, 0.298); // redfixed3 col3 = float3(0.867, 0.910, 0.247); // yellowfixed3 ret;ret = bgCol;// 固定的坐标系ret = lerp(ret, col1, coordinateGrid(r) / 2.0);// 缩放float2 q = _ScaleValue*r;ret = lerp(ret, col2, coordinateGrid(q));// 画各个图形//在原始坐标系中画ret = lerp(ret, col1, disk(r, float2(0.0, 0.0), 0.1));ret = lerp(ret, col1, rectangle(r, float2(-0.5, 0.0),float2(-0.2, 0.2)));//在可缩放坐标系中画ret = lerp(ret, col2, disk(q, float2(0.0, 0.0), 0.1)); //大ret = lerp(ret, col2, rectangle(q, float2(-0.5, 0.0),float2(-0.2, 0.2))); //大fixed3 pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

8、平移以及旋转和平移的组合，效果如图所示，这个Shader部分分了两个部分对旋转和平移进行组合使用，分别是

先旋转在平移和先平移再旋转，Shader的代码如下：

Shader "Unlit/Chapter6-Transform"{Properties{_RotationAngle("旋转角",Range(0,360))=0_LRotatedTranslatedX("左半部分X方向平移",Range(0,1))=0_LRotatedTranslatedY("左半部分Y方向平移",Range(0,1))=0_RRotatedTranslatedX("右半部分X方向平移",Range(0,1)) = 0_RRotatedTranslatedY("右半部分Y方向平移",Range(0,1)) = 0}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDE#define PI 3.1415926// 通过函数来画网格float coordinateGrid(float2 r) {float3 axisCol = float3(0.0, 0.0, 1.0);float3 gridCol = float3(0.5, 0.5, 0.5);float ret = 0.0;// 画网线const float tickWidth = 0.1;for (float i = -2.0; i<2.0; i += tickWidth) {ret += 1.0 - smoothstep(0.0, 0.008, abs(r.x - i));ret += 1.0 - smoothstep(0.0, 0.008, abs(r.y - i));}// 画坐标轴ret += 1.0 - smoothstep(0.001, 0.015, abs(r.x));ret += 1.0 - smoothstep(0.001, 0.015, abs(r.y));return ret;}// 圆内的返回1float disk(float2 r, float2 center, float radius) {return 1.0 - smoothstep(radius - 0.005, radius + 0.005, length(r - center));}// 在长方形内返回1float rectangle(float2 r, float2 bottomLeft, float2 topRight) {float ret;float d = 0.005;ret = smoothstep(bottomLeft.x - d, bottomLeft.x + d, r.x);ret *= smoothstep(bottomLeft.y - d, bottomLeft.y + d, r.y);ret *= 1.0 - smoothstep(topRight.y - d, topRight.y + d, r.y);ret *= 1.0 - smoothstep(topRight.x - d, topRight.x + d, r.x);return ret;}ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform float _RotationAngle;uniform float _LRotatedTranslatedX;uniform float _LRotatedTranslatedY;uniform float _RRotatedTranslatedX;uniform float _RRotatedTranslatedY;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}//坐标旋转和平移fixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 bgCol = float3(1.0, 1.0, 1.0); // whitefixed3 col1 = float3(0.216, 0.471, 0.698); // bluefixed3 col2 = float3(1.00, 0.329, 0.298); // redfixed3 col3 = float3(0.867, 0.910, 0.247); // yellowfixed3 ret;ret = bgCol;float angle = _RotationAngle/PI;float2x2 rotationMatrix = float2x2(cos(angle), -sin(angle),sin(angle), cos(angle));//分两部分进行转换//左半部分if (i.uv.x < 1.0 / 2.0) {r = r - float2(-aspectRatio / 2.0, 0);float2 rotated = mul(rotationMatrix, r);float2 rotatedTranslated = rotated - float2(_LRotatedTranslatedX, _LRotatedTranslatedY);//原始坐标ret = lerp(ret, col1, coordinateGrid(r) * 0.3);//旋转坐标ret = lerp(ret, col2, coordinateGrid(rotated)*0.3);//旋转再平移ret = lerp(ret, col3, coordinateGrid(rotatedTranslated)*0.3);//原始坐标的图形ret = lerp(ret, col1, rectangle(r, float2(-0.1, -0.2), float2(0.1, 0.2)));//旋转之后的坐标图形ret = lerp(ret, col2, rectangle(rotated, float2(-0.1, -0.2), float2(0.1, 0.2)));//旋转再平移之后ret = lerp(ret, col3, rectangle(rotatedTranslated, float2(-0.1, -0.2), float2(0.1, 0.2)));}//右半部分else if (i.uv.x < 2.0 / 2.0) { r = r - float2(aspectRatio / 2.0, 0);//平移float2 translated = r - float2(_RRotatedTranslatedX, _RRotatedTranslatedY);//平移再旋转float2 translatedRotated = mul(rotationMatrix, translated);//原始坐标ret = lerp(ret, col1, coordinateGrid(r) * 0.3);//平移ret = lerp(ret, col2, coordinateGrid(translated)*0.3);//平移之后再旋转ret = lerp(ret, col3, coordinateGrid(translatedRotated)*0.3);ret = lerp(ret, col1, rectangle(r, float2(-0.1, -0.2), float2(0.1, 0.2)));ret = lerp(ret, col2, rectangle(translated, float2(-0.1, -0.2), float2(0.1, 0.2)));ret = lerp(ret, col3, rectangle(translatedRotated, float2(-0.1, -0.2), float2(0.1, 0.2)));}fixed3 pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

三、放两个大招—各种动画效果

1、效果如图所示：从左到右分别是五个不同的动画效果，使用到的函数都是前面讲解的函数加上之后补充的旋转、缩放和平移效果。

Shader代码如下：（原文地址凯尔八阿哥专栏，转载请注明出处）

Shader "Unlit/Chapter6-Animations"{Properties{_SpeedY("第一部分的速度",Range(0,3)) = 1_Amplitude("第二部分的振幅",Range(0,1)) = 0.8_RSpeedX("圆周运动X方向的速度",Range(0,10)) = 5_RSpeedY("圆周运动Y方向的速度",Range(0,10)) = 5_RAmplitudeY("圆周运动Y方向的幅度",Range(0,1)) = 0.1_RAmplitudeX("圆周运动X方向的幅度",Range(0,1)) = 0.1_ChainAnimSpeed("链条运动的速度",Range(0,10)) = 5_ChainAnimRotaSpeed("链条运动的旋转速度",Range(0,10)) = 3_JumpSpeed("跳跃运动的速度",Range(0,10))=2}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDE#define PI 3.1415926// 通过函数来画网格float coordinateGrid(float2 r) {float3 axisCol = float3(0.0, 0.0, 1.0);float3 gridCol = float3(0.5, 0.5, 0.5);float ret = 0.0;// 画网线const float tickWidth = 0.1;for (float i = -2.0; i<2.0; i += tickWidth) {ret += 1.0 - smoothstep(0.0, 0.008, abs(r.x - i));ret += 1.0 - smoothstep(0.0, 0.008, abs(r.y - i));}// 画坐标轴ret += 1.0 - smoothstep(0.001, 0.015, abs(r.x));ret += 1.0 - smoothstep(0.001, 0.015, abs(r.y));return ret;}// 圆内的返回1float disk(float2 r, float2 center, float radius) {return 1.0 - smoothstep(radius - 0.005, radius + 0.005, length(r - center));}// 在长方形内返回1float rectangle(float2 r, float2 bottomLeft, float2 topRight) {float ret;float d = 0.005;ret = smoothstep(bottomLeft.x - d, bottomLeft.x + d, r.x);ret *= smoothstep(bottomLeft.y - d, bottomLeft.y + d, r.y);ret *= 1.0 - smoothstep(topRight.y - d, topRight.y + d, r.y);ret *= 1.0 - smoothstep(topRight.x - d, topRight.x + d, r.x);return ret;}float mod(float  a, float  b) { return a - b*floor(a / b); }ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform float _Amplitude;uniform float _SpeedY;uniform float _RSpeedX;uniform float _RSpeedY;uniform float _RAmplitudeY;uniform float _RAmplitudeX;uniform float _ChainAnimSpeed;uniform float _ChainAnimRotaSpeed;uniform float _JumpSpeed;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}//动画，使用到了Unity内置的变量_Time 四维向量(t/20, t, t*2, t*3)，_Time.y=t;fixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;fixed3 bgCol = float3(1.0, 1.0, 1.0); // whitefixed3 col1 = float3(0.216, 0.471, 0.698); // bluefixed3 col2 = float3(1.00, 0.329, 0.298); // redfixed3 col3 = float3(0.867, 0.910, 0.247); // yellowfixed3 ret;ret = bgCol;//第一部分,循环向上运动if (i.uv.x < 1.0 / 5.0) {float2 q = r + float2(aspectRatio*4.0 / 5.0, 0);ret = fixed3(0.3, 0.3, 0.3);//unity内置的时间向量float y = _SpeedY*_Time.y;//使得y在-1到1之间y = mod(y,2.0) - 1.0;ret = lerp(ret, col1, disk(q, float2(0.0, y), 0.1));}//第二部分，循环来回并缩放运动else if (i.uv.x < 2.0 / 5.0) {float2 q = r + float2(aspectRatio*2.0 / 5.0, 0);ret = fixed3(0.4, 0.4, 0.4);//添加振幅float y = _Amplitude * sin(0.5*_Time.y* 2.0 * PI);float radius = 0.15 + 0.05 * sin(_Time.y * 8.0);ret = lerp(ret, col1, disk(q, float2(0.0, y), radius));}//第三部分，圆周运动并变换颜色else if (i.uv.x < 3.0 / 5.0) {float2 q = r + float2(aspectRatio * 0 / 5.0, 0);ret = float3(0.5, 0.5, 0.5);float x = _RAmplitudeX*cos(_Time.y*_RSpeedX);float y = _RAmplitudeY*sin(_Time.y*_RSpeedY);float radius = 0.2 + 0.1*sin(_Time.y*2.0);fixed3 color = lerp(col1, col2, sin(_Time.y)*0.5 + 0.5);ret = lerp(ret, color, rectangle(q, float2(x - 0.1, y - 0.1), float2(x + 0.1, y + 0.1)));}//第四部分，链条运动else if (i.uv.x < 4.0 / 5.0) {float2 q = r + float2(-aspectRatio*2.0 / 5.0, 0);ret = float3(0.4, 0.4, 0.4);for (float i = -1.0; i<1.0; i += 0.2){float x = 0.2 * cos(_Time.y*_ChainAnimSpeed + i*PI);float y = i;float2 s = q - float2(x, y);float angle = _Time.y * _ChainAnimRotaSpeed + i;float2x2 rot = float2x2(cos(angle), -sin(angle),sin(angle),  cos(angle));s = mul(rot, s);ret = lerp(ret, col1, rectangle(s, float2(-0.06, -0.06), float2(0.06, 0.06)));}}//第五部分，跳跃运动else if (i.uv.x < 5.0 / 5.0) {float2 q = r + float2(-aspectRatio*4.0 / 5.0, 0);ret = float3(0.3, 0.3, 0.3);float speed = _JumpSpeed;float t = _Time.y * speed;float stopEveryAngle = PI / 2.0;float stopRatio = 0.5;//floor(x):返回小于等于t的最大整数     frac(x):返回x的小数部分float t1 = (floor(t) + smoothstep(0.0, 1.0 - stopRatio, frac(t)))*stopEveryAngle;float x = -0.2*cos(t1);float y = 0.3 * sin(t1);float dx = 0.1 + 0.03 * sin(t*10.0);float dy = 0.1 + 0.03 * sin(t*10.0 + PI);ret = lerp(ret, col1, rectangle(q, float2(x - dx, y - dy), float2(x + dx, y + dy)));}fixed3 pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

代码中使用到了“_Time”变量，这个是Unity内置的四维向量，（t/20,t,t*2,t*3）因此“_Time.y=t”即获得系统的渲染的单位时间。
2、等离子流动效果，效果图如图所示：

Shader代码如下：

Shader "Unlit/Chapter6-Plasma"{Properties{_WaveSpeed("波浪速度",Range(0,10))=8_ColorValue1("混合颜色1",Range(0,360))=180_ColorValue2("混合颜色2",Range(0,360)) = 180}SubShader{// No culling or depthCull Off ZWrite Off ZTest AlwaysCGINCLUDE#define PI 3.1415926ENDCGPass{CGPROGRAM#pragma vertex vert#pragma fragment frag#include "UnityCG.cginc"uniform float _WaveSpeed;uniform float _ColorValue1;uniform float _ColorValue2;struct appdata{float4 vertex : POSITION;float2 uv : TEXCOORD0;};struct v2f{float2 uv : TEXCOORD0;float4 vertex : SV_POSITION;};v2f vert(appdata v){v2f o;o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);o.uv = v.uv;o.uv.y = 1 - o.uv.y;return o;}//等离子效果fixed4 frag(v2f i) : SV_Target{float2 r = 2.0 * (i.uv - 0.5);float aspectRatio = _ScreenParams.x / _ScreenParams.y;r.x *= aspectRatio;float t = _Time.y*_WaveSpeed;r = r*8.0;float v1 = sin(r.x + t);float v2 = sin(r.y + t);float v3 = sin(r.x + r.y + t);float v4 = sin(sqrt(r.x*r.x + r.y*r.y) + 1.7*t);float v = v1 + v2 + v3 + v4;fixed3 ret;//第一部分垂直波浪if (i.uv.x < 1.0 / 10.0) {ret = float3(v1, v1, v1)}//第二部分水平波浪else if (i.uv.x < 2.0 / 10.0){ret = float3(v2, v2, v2);}//第三部分对角线波浪else if (i.uv.x < 3.0 / 10.0) {ret = float3(v3, v3, v3);}//第四部分圆环波浪else if (i.uv.x < 4.0 / 10.0) {ret = float3(v4, v4, v4);}//第五部分所有波浪的综合else if (i.uv.x < 5.0 / 10.0) {ret = float3(v, v, v);}//第六部分通过正、余弦函数添加周期性渐变else if (i.uv.x < 6.0 / 10.0){ret = float3(sin(2.0 * v), sin(2.0 * v), sin(2.0 * v));}//第七部分混合各种颜色else if (i.uv.x < 10.0 / 10.0) {ret = float3(sin(v), sin(v + _ColorValue1/PI), sin(v + _ColorValue2/PI));}ret = 0.5 + 0.5 * ret;fixed3 pixel = ret;return fixed4(pixel, 1.0);}ENDCG}}}

四、总结

1、Cg函数虽简单，使用得当也是逼格暴涨，对于想学好Shader童鞋来讲，还是要多从Cg语言基础着手，通过实例练习，不仅可以巩固基础知识，而且也可以在做的过程中添加学习的信心和兴趣。

2、正弦、余弦函数配合时间变量的使用能做到非常不错的动画效果，最好的效果还是要从根本上来讲还是数学，当今世界是学好数学和英语走遍天下都不怕了。