/* this is aboutl the 2x2 matrix thing. the other was
about something else */
/* It was about building a (ascii)
text display screen that would be cross platform
h:\tc\whatever loads first
*/

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>
#include<alloc.h> /* gcc  wanted malloc.h here */
#include<assert.h>
#include<time.h>
#define PI 3.1415927
struct vector2d
 {float x;
  float y;
  };
int    graphdriver;	/* The Graphics device driver		*/
int    graphmode;	/* The Graphics mode value */
int goodstatus; /* flag for assert */
int myfill(int color);
/* ..........................."the constants"......... */
float cs(float th);
float sn(float th);
float ncs(float th);
float nsn(float th);
float one(float th);
float negone(float th);
float zero(float th);
/* .........................."the variables".......... */
float (*a)(float th);
float (*b)(float th);
float (*c)(float th);
float (*d)(float th);
/* ........................................................ */
int putpoint(struct vector2d *point, int pixcolor);
struct
 vector2d
  *rowmult(float a11,float a12,float a21,float a22,struct vector2d *w);
struct vector2d *to_origin(struct vector2d *w);
struct vector2d *from_origin(struct vector2d *w);
main()
{
int testx,testy,index,counter;
float theta,r,pi2,loopend;
/* int *dummy1,*dummy2; */
struct vector2d *v,*u;

u=(struct vector2d *) malloc(sizeof(struct vector2d));
v=(struct vector2d *) malloc(sizeof(struct vector2d));
/* dummy1=(struct int *) malloc(sizeof(struct int));
   dummy2=(struct int *) malloc(sizeof(struct int)); */
  /*............................................*/
    graphdriver = DETECT ;
      initgraph ( &graphdriver, &graphmode, "");
	/*............................................*/
randomize();
pi2=2*PI;
goodstatus=1;
myfill(13);
circle(20,20,10); /* for testing purposes */
/* the test patterns */
/* we are going to build the test patterns */
/* dotgrid */
for(testx=10;testx<200;testx+=10)
 for(testy=10;testy<200;testy+=10)
  putpixel(testx,testy,3);
/* getch(); */
/*_______________________testing matmult__________  */
/* ................................................ */
a=&cs;b=&nsn;c=&sn;d=&cs; /* these assignments soon superceded by switches */
for(counter=0;counter<100;counter++){
cleardevice();
index=random(7);
switch(index)
  {
   case 0: a=&cs    ;break;
   case 1: a=&sn    ;break;
   case 2: a=&ncs   ;break;
   case 3: a=&nsn   ;break;
   case 4: a=&one   ;break;
   case 5: a=&negone;break;
   case 6: a=&zero  ;break;
   default: outtextxy(20,440," default rang in switch ");
  }
index=random(7);
switch(index)
  {
   case 0: b=&cs    ;break;
   case 1: b=&sn    ;break;
   case 2: b=&ncs   ;break;
   case 3: b=&nsn   ;break;
   case 4: b=&one   ;break;
   case 5: b=&negone;break;
   case 6: b=&zero  ;break;
   default: outtextxy(20,440," default rang in switch ");
  }index=random(7);
switch(index)
  {
   case 0: c=&cs    ;break;
   case 1: c=&sn    ;break;
   case 2: c=&ncs   ;break;
   case 3: c=&nsn   ;break;
   case 4: c=&one   ;break;
   case 5: c=&negone;break;
   case 6: c=&zero  ;break;
   default: outtextxy(20,440," default rang in switch ");
  }index=random(7);
switch(index)
  {
   case 0: d=&cs    ;break;
   case 1: d=&sn    ;break;
   case 2: d=&ncs   ;break;
   case 3: d=&nsn   ;break;
   case 4: d=&one   ;break;
   case 5: d=&negone;break;
   case 6: d=&zero  ;break;
   default: outtextxy(20,440," default rang in switch ");
  }
myfill(0);

loopend=3.0*pi2;
for(theta=0.0;theta<loopend;theta=theta+0.1)
{
myfill(0);
for (u->y=20.0;u->y < 280.0;u->y+=20.0)
 for (u->x=20.0;u->x < 280.0;u->x+=1.0)
  {
  v=to_origin(u);
  v=rowmult(   (*a)(theta), (*b)(theta),
	       (*c)(theta), (*d)(theta),
	       v
	     );
  v=from_origin(v);
  goodstatus=putpoint(v,index);
  }
 }
}
outtextxy(10,380,"Just did the test putpoint(u) loop text.");
/*   ................................................ */
/*_______________________end testing matmult__________  */
getch();
myfill(2);
/* line of dots grid */
for(testx=10;testx<400;testx+=10)
 for(testy=10;testy<400;testy++)
  putpixel(testx,testy,4);
for(testy=10;testy<400;testy+=10)
 for(testx=10;testx<400;testx++)
  putpixel(testx,testy,4);
 getch();
myfill(0);
/* circles (or dots) ----------------------------- */
for(r=10.0;r<150.0;r+=10.0)
 for(theta=0.0;theta<pi2;theta+=0.05)
 {

  testx=200.0+r*cos(theta);testy=200.0+r*sin(theta);
  putpixel(testx,testy,5);
 }
free(u);free(v);
outtextxy(10,380,"...........done.......");
getch();
closegraph();
return(1);
}
struct vector2d *to_origin(struct vector2d *w)
{
 struct vector2d *result;
 result->x = w->x - 150;
 result->y = w->y - 150;
 return(result);
}
struct vector2d *from_origin(struct vector2d *w)
{
 struct vector2d *result;
 result->x = w->x + 150;
 result->y = w->y + 150;
 return(result);
}
struct
 vector2d
  *rowmult(float a11,float a12,float a21,float a22,struct vector2d *w)
  {
   struct vector2d *result;
   result->x = a11*w->x + a12*w->y;
   result->y = a21*w->x + a22*w->y;
/*   assert(goodstatus); */
     if (!goodstatus)
     goodstatus=goodstatus;
   return(result);
   }
int putpoint(struct vector2d *point, int pixcolor)
 {
  if( (point->x >   5.0) &&
      (point->x < 295.0) &&
      (point->y >   5.0) &&
      (point->y < 295.0)
     )
   {putpixel(180+point->x,20+point->y,pixcolor);return(1);}
  else return(0);
  }
int myfill(int color)
 {
  setfillstyle(SOLID_FILL,color);
  bar(10,10,590,390);
  return(1);
 }

float cs(float th){return(  0.7*cos(th));}
float sn(float th){return(  0.7*sin(th));}
float ncs(float th){return( -0.7*cos(th));}
float nsn(float th){return( -0.7*sin(th));}
float one(float th){return(1.0);}
float negone(float th){return(-1.0);}
float zero(float th){return(0.0);}