[C++] 几行代码生成漂亮图片，数学家就是牛！

信息获得处：http://news.cnblogs.com/n/501488/

 分形：http://baike.baidu.com/subview/83243/11213590.htm?fr=aladdin

代码：[采用宏定义的来选择绘制不同的图，所以把最后两个给注释掉了，因为宏冲突，想自己试试可以单独编译运行]

PS:生成的图片是ppm格式的要用格式工厂之类的软件进行转换，也可以自己在程序里直接把图片生成bmp或者其他格式的~

// NOTE: compile with g++ filename.cpp -std=c++11  
#include <iostream>
#include <cmath>
#include <cstdlib> 
#define DIM 1024 
#define DM1 (DIM-1) 
#define _sq(x) ((x)*(x)) // square 
#define _cb(x) abs((x)*(x)*(x)) // absolute value of cube 
#define _cr(x) (unsigned char)(pow ((x),1.0/3.0)) // cube root
#define F
 
unsigned char GR (int,int);
unsigned char BL (int,int);
 
unsigned char RD (int i,int j){
    #ifdef A
    return (char)(_sq(cos(atan2(j-512,i-512)/2))*255);
    #endif

    #ifdef B
    #define r(n) (rand ()%n) 
    static char c[1024][1024];
    return!c[i][j]?c[i][j]=!r(999)?r(256):RD ((i+r(2))%1024,(j+r(2))%1024):c[i][j];
    #endif

    #ifdef C
    float x=0,y=0;
    int k;
    for(k=0;k++<256;){
        float a=x*x-y*y+ (i-768.0)/512;
        y=2*x*y+ (j-512.0)/512;
        x=a;
        if(x*x+y*y>4)break;
    }
    return log (k)*47;
    #endif

    #ifdef D
    double a=0,b=0,c,d,n=0;
    while((c=a*a)+(d=b*b)<4&&n++<880){
        b=2*a*b+j*8e-9-.645411;
        a=c-d+i*8e-9+.356888;
    }
    return 255*pow ((n-80)/800,3.);
    #endif

    #ifdef E
    static double k;
    k+=rand ()/1./RAND_MAX;
    int l=k;
    l%=512;
    return l>255?511-l:l;
    #endif

    #ifdef F
    float s=3./(j+99);
    float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
    return (int((i+DIM)*s+y)%2+int((DIM*2-i)*s+y)%2)*127;
    #endif
/*
    #ifdef G
    #define D DIM 
    #define M m[(x+D+ (d==0)-(d==2))%D][(y+D+ (d==1)-(d==3))%D] 
    #define R rand ()%D 
    #define B m[x][y] 
    return(i+j)?256-(BL (i,j))/2:0;
    #endif
*/
/*
    #ifdef H
    #define A float a=0,b,k,r,x 
    #define B int e,o 
    #define C (x) x>255?255:x 
    #define R return #define D DIM 
    R BL (i,j)*(D-i)/D;
    #endif
*/
    return 0;
}
unsigned char GR (int i,int j){
    #ifdef A
    return (char)(_sq (cos (atan2(j-512,i-512)/2-2*acos (-1)/3))*255);
    #endif

    #ifdef B
    static char c[1024][1024];
    return!c[i][j]?c[i][j]=!r(999)?r(256):GR ((i+r(2))%1024,(j+r(2))%1024):c[i][j];
    #endif

    #ifdef C
    float x=0,y=0;
    int k;
    for(k=0;k++<256;){
        float a=x*x-y*y+ (i-768.0)/512;
        y=2*x*y+ (j-512.0)/512;
        x=a;
        if(x*x+y*y>4)break;
    }
    return log (k)*47;
    #endif

    #ifdef D
    double a=0,b=0,c,d,n=0;
    while((c=a*a)+(d=b*b)<4&&n++<880){
        b=2*a*b+j*8e-9-.645411;
        a=c-d+i*8e-9+.356888;
    }
    return 255*pow ((n-80)/800,.7);
    #endif

    #ifdef E
    static double k;
    k+=rand ()/1./RAND_MAX;
    int l=k;
    l%=512;
    return l>255?511-l:l;
    #endif

    #ifdef F
    float s=3./(j+99);
    float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
    return (int(5*((i+DIM)*s+y))%2+int(5*((DIM*2-i)*s+y))%2)*127;
    #endif
/*
    #ifdef G
    #define A 
    static int m[D][D],e,x,y,d,c[4],f,n;
    if (i+j<1){
        for (d=D*D;d;d--){
            m[d%D][d/D]=d%6?0:rand ()%2000?1:255;
        }
        for (n=1 return RD (i,j);
    #endif
*/
/*
    #ifdef H
    #define E DM1 
    #define F static float 
    #define G for ( 
    #define H r=a*1.6/D+2.4;x=1.0001*b/D
    R BL (i,j)*(D-j/2)/D;
    #endif
*/
    return 0;
}
unsigned char BL (int i,int j){
    #ifdef A
    return (char)(_sq (cos (atan2(j-512,i-512)/2+2*acos (-1)/3))*255);
    #endif

    #ifdef B
    static char c[1024][1024];
    return!c[i][j]?c[i][j]=!r(999)?r(256):BL((i+r(2))%1024,(j+r(2))%1024):c[i][j];
    #endif

    #ifdef C
    float x=0,y=0;
    int k;
    for(k=0;k++<256;){
        float a=x*x-y*y+ (i-768.0)/512;
        y=2*x*y+ (j-512.0)/512;
        x=a;
        if(x*x+y*y>4)break;
    }
    return 128-log (k)*23;
    #endif

    #ifdef D
    double a=0,b=0,c,d,n=0;
    while((c=a*a)+(d=b*b)<4&&n++<880){
        b=2*a*b+j*8e-9-.645411;
        a=c-d+i*8e-9+.356888;
    }
    return 255*pow ((n-80)/800,.5);
    #endif

    #ifdef E
        static double k;
        k+=rand ()/1./RAND_MAX;
        int l=k;
        l%=512;
        return l>255?511-l:l;
    #endif    

    #ifdef F
    float s=3./(j+99);
    float y=(j+sin ((i*i+_sq (j-700)*5)/100./DIM)*35)*s;
    return (int(29*((i+DIM)*s+y))%2+int(29*((DIM*2-i)*s+y))%2)*127;
    #endif
/*
    #ifdef G
    A;n;n++){
        x=R;y=R;
        if(B==1){
            f=1;
            for(d=0;d<4;d++){
                c[d]=M;
                f=f<c[d]?c[d]:f;
            }
            if(f>2){B=f-1;}
            else{
                ++e%=4;
                d=e;
                if(!c[e]){
                    B=0;M=1;
                }}}}}
    return m[i][j];
    #endif
*/
/*
    #ifdef H
    F c[D][D];
    if(i+j<1){A;B;G;a<D;a+=0.1){G b=0;b<D;b++){H;G k=0;k<D;k++){x=r*x*(1-x);
    if(k>D/2){e=a;o=(E*x);c[e][o]+=0.01;}}}}}
    R C (c[j][i])*i/D;
    #endif
*/

    return 0;
}
 
void pixel_write (int,int);
FILE *fp;
int main (){
    fp = fopen ("MathPic.ppm","wb");
    fprintf (fp, "P6
%d %d
255
", DIM, DIM);
    for(int j=0;j<DIM;j++)
        for(int i=0;i<DIM;i++)
            pixel_write (i,j);
    fclose (fp);
    return 0;
}
void pixel_write (int i, int j){
    static unsigned char color[3];
    color[0] = RD (i,j)&255;
    color[1] = GR (i,j)&255;
    color[2] = BL (i,j)&255;
    fwrite (color, 1, 3, fp);
}