#include "library.h"
      
      const double pi=acos(-1);
      
      const int scrw=500, scrh=500;
      
      struct point
      { double x, y; };
      
      void print(point p)
      { print("(");
        print(p.x);
        print(",");
        print(p.y);
        print(")"); }
      
      double distance(point a, point b)
      { return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)); }
      
      point rotate(point p, double angle)
      { double r=sqrt(p.x*p.x+p.y*p.y);
        double theta=atan2(p.x, p.y);
        theta=theta+angle;
        point q;
        q.x=r*sin(theta);
        q.y=r*cos(theta);
        return q; }
      
      point scale(point p, double factor)
      { point q;
        q.x=p.x*factor;
        q.y=p.y*factor;
        return q; }
      
      struct point3d
      { double x, y, z; };
      
      point3d rotatex(point3d p, double a)
      { point3d q;
        q.x=p.x;  
        q.y=p.y*cos(a)+p.z*sin(a);
        q.z=p.z*cos(a)-p.y*sin(a);
        return q; }
      
      point3d rotatey(point3d p, double a)
      { point3d q;
        q.x=p.x*cos(a)+p.z*sin(a);
        q.y=p.y;  
        q.z=p.z*cos(a)-p.x*sin(a);
        return q; }
      
      point3d rotatez(point3d p, double a)
      { point3d q;
        q.x=p.x*cos(a)+p.y*sin(a);
        q.y=p.y*cos(a)-p.x*sin(a);
        q.z=p.z;  
        return q; }
      
      point project(point3d p)
      { const double from=500;
        const double scale=from/(from-p.z);
        point q;
        q.x=p.x*scale+scrw/4;
        q.y=p.y*scale+scrh/2;
        return q; }
      
      struct cube
      { point3d p1, p2, p3, p4, p5, p6, p7, p8; };
      
      cube rotatex(cube c, double a)
      { cube d;
        d.p1=rotatex(c.p1, a);
        d.p2=rotatex(c.p2, a);
        d.p3=rotatex(c.p3, a);
        d.p4=rotatex(c.p4, a);
        d.p5=rotatex(c.p5, a);
        d.p6=rotatex(c.p6, a);
        d.p7=rotatex(c.p7, a);
        d.p8=rotatex(c.p8, a);
        return d; }
      
      cube rotatey(cube c, double a)
      { cube d;
        d.p1=rotatey(c.p1, a);
        d.p2=rotatey(c.p2, a);
        d.p3=rotatey(c.p3, a);
        d.p4=rotatey(c.p4, a);
        d.p5=rotatey(c.p5, a);
        d.p6=rotatey(c.p6, a);
        d.p7=rotatey(c.p7, a);
        d.p8=rotatey(c.p8, a);
        return d; }
      
      cube rotatez(cube c, double a)
      { cube d;
        d.p1=rotatez(c.p1, a);
        d.p2=rotatez(c.p2, a);
        d.p3=rotatez(c.p3, a);
        d.p4=rotatez(c.p4, a);
        d.p5=rotatez(c.p5, a);
        d.p6=rotatez(c.p6, a);
        d.p7=rotatez(c.p7, a);
        d.p8=rotatez(c.p8, a);
        return d; }
      
      void draw(cube c)
      { PenColor(PEN_BLUE);
        PenWidth(3);
        point p;
        p=project(c.p1);
        MoveTo(p.x, p.y);
        p=project(c.p2);
        DrawLineTo(p.x, p.y);
        p=project(c.p3);
        DrawLineTo(p.x, p.y);
        p=project(c.p4);
        DrawLineTo(p.x, p.y);
        p=project(c.p1);
        DrawLineTo(p.x, p.y);
        p=project(c.p5);
        MoveTo(p.x, p.y);
        p=project(c.p6);
        DrawLineTo(p.x, p.y);
        p=project(c.p7);
        DrawLineTo(p.x, p.y);
        p=project(c.p8);
        DrawLineTo(p.x, p.y);
        p=project(c.p5);
        DrawLineTo(p.x, p.y);
        p=project(c.p1);
        MoveTo(p.x, p.y);
        p=project(c.p5);
        DrawLineTo(p.x, p.y);
        p=project(c.p2);
        MoveTo(p.x, p.y);
        p=project(c.p6);
        DrawLineTo(p.x, p.y);
        p=project(c.p3);
        MoveTo(p.x, p.y);
        p=project(c.p7);
        DrawLineTo(p.x, p.y);
        p=project(c.p4);
        MoveTo(p.x, p.y);
        p=project(c.p8);
        DrawLineTo(p.x, p.y); }
      
      void whiteout(void)
      { PenColor(PEN_WHITE);
        FillRectangleXYWH(0, 0, 500, 500); }
      
      void main(void)
      { cube xxx = { { 70, 70, 70 }, { 210, 70, 70 }, { 210, 70, -70 }, { 70, 70, -70 },
                     { 70, 210, 70 }, { 210, 210, 70 }, { 210, 210, -70 }, { 70, 210, -70 } };
        MakeWindow(scrw, scrh);
        while (true)
        { draw(xxx);
          xxx = rotatex(xxx, 0.03);
          xxx = rotatey(xxx, 0.01);
          Delay(0.03);
          whiteout(); } }