Raytracer

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

FILE * m;

typedef int i;
typedef float f;

struct v{
    f x,y,z;

    v operator+(v r){
        return v(x+r.x,y+r.y,z+r.z);
    }

    v operator*(f r){
        return v(x*r,y*r,z*r);
    }

    f operator%(v r){
        return x*r.x+y*r.y+z*r.z;
    }

    v(){}

    v operator^(v r){
        return v(y*r.z-z*r.y,z*r.x-x*r.z,x*r.y-y*r.x);
    }

    v(f a,f b,f c){
        x=a;y=b;z=c;
    }

    v operator!(){
        return *this*(1/sqrt(*this%*this));
    }
};

i G[]={247570,280596,280600,249748,18578,18577,231184,16,16};

f R(){
    return(f)rand()/RAND_MAX;
}


i T(v o,v d,f&t,v&n){
    t=1e9;
    i m=0;
    f p=-o.z/d.z;
    if(.01<p)t=p,n=v(0,0,1),m=1;

    for(i k=19;k--;)
        for(i j=9;j--;)
            if(G[j]&1<<k){
                v p=o+v(-k,0,-j-4);
                f b=p%d,c=p%p-1,q=b*b-c;
                if(q>0){
                    f s=-b-sqrt(q);

                    if(s<t&&s>.01)
                        t=s,n=!(p+d*t),m=2;
                }
            }
            return m;
}

v S(v o,v d){
    f t;
    v n;
    i m=T(o,d,t,n);

    if(!m)return v(.7,.6,1)*pow(1-d.z,4);

    v h=o+d*t,l=!(v(9+R(),9+R(),16)+h*-1),r=d+n*(n%d*-2);

    f b=l%n;

    if(b<0||T(h,l,t,n))
        b=0;

    f p=pow(l%r*(b>0),99);

    if(m&1){
        h=h*.2;
        return((i)(ceil(h.x)+ceil(h.y))&1?v(3,1,1):v(3,3,3))*(b*.2+.1);
    }

    return v(p,p,p)+S(h,r)*.5;
}

i main()
{
    m=fopen("f.ppm","w");
    fprintf(m,"P6 512 512 255 ");

    v g=!v(-6,-16,0),a=!(v(0,0,1)^g)*.002,b=!(g^a)*.002,c=(a+b)*-256+g;

    for(i y=512;y--;)
        for(i x=512;x--;)
        {
            v p(13,13,13);
            for(i r=64;r--;)
            {
                v t=a*(R()-.5)*99+b*(R()-.5)*99;
                p=S(v(17,16,8)+t,!(t*-1+(a*(R()+x)+b*(y+R())+c)*16))*3.5+p;
            }
            fprintf(m,"%c%c%c",(i)p.x,(i)p.y,(i)p.z);
        }
}