/* s_text.c (comment6.c) - Spherical scroller - Don Yang (uguu.org)

   DOS only.

   MSC 6.0:
      cl /FPi87 /G2rs /Ox /W4 s_text.c

   04/08/99: main
             blit
             render
                                                                           */

/* Includes */
#include<conio.h>
#include<math.h>

/* Constants */
#define SCREEN          0xb8000000
#define CLOCK           0x0040006c
/*#define DISABLEVSYNC                    */

/* Data (all data are global) */
int far *video = (int far *)SCREEN;
int OldScreen[2000];
char screen[4000];
int palette[16] =                       /* top << 2 | bottom */
   {0x0000, 0x0adc, 0x07dc, 0x0fdc,       /* 0 = black */
    0x0adf, 0x0adb, 0x7adf, 0x7adf,       /* 1 = green */
    0x70dc, 0x7adc, 0x77dc, 0x7fdc,       /* 2 = gray */
    0x0fdf, 0x7adc, 0x7fdf, 0x0fdb};      /* 3 = white */
char image[2][8][28] =
   { { {0,2,2,2,2,2,0,0,0,  0,0,0,0,2,2,0,0,0,0,  0,0,2,0,0,0,0,2,0},
       {2,3,3,3,3,3,2,0,0,  0,0,0,2,3,3,2,0,0,0,  0,2,3,2,0,0,2,3,2},
       {2,3,2,2,2,2,3,2,0,  0,0,2,3,2,2,3,2,0,0,  0,2,3,3,2,0,2,3,2},
       {2,3,2,0,0,2,3,2,0,  0,2,3,2,0,0,2,3,2,0,  0,2,3,2,3,2,2,3,2},
       {2,3,2,0,0,2,3,2,0,  0,2,3,2,0,0,2,3,2,0,  0,2,3,2,2,3,2,3,2},
       {2,3,2,2,2,2,3,2,0,  0,0,2,3,2,2,3,2,0,0,  0,2,3,2,0,2,3,3,2},
       {2,3,3,3,3,3,2,0,0,  0,0,0,2,3,3,2,0,0,0,  0,2,3,2,0,0,2,3,2},
       {0,2,2,2,2,2,0,0,0,  0,0,0,0,2,2,0,0,0,0,  0,0,2,0,0,0,0,2,0} },

     { {1,0,0,0,0,1,0,  0,0,1,1,0,0,0,  1,1,1,0,0,1,0,  0,0,1,1,1,1,0},
       {1,0,0,0,0,1,0,  0,1,0,0,1,0,0,  1,0,0,1,0,1,0,  0,1,0,0,0,0,0},
       {1,0,0,0,0,1,0,  1,0,0,0,0,1,0,  1,0,0,0,1,1,0,  1,0,0,0,0,0,0},
       {0,1,1,1,1,1,0,  1,0,0,0,0,1,0,  1,0,0,0,0,1,0,  1,0,0,0,0,0,0},
       {0,0,0,0,0,1,0,  1,1,1,1,1,1,0,  1,0,0,0,0,1,0,  1,0,0,1,1,0,0},
       {0,0,0,0,0,1,0,  1,0,0,0,0,1,0,  1,0,0,0,0,1,0,  1,0,0,0,0,1,0},
       {0,0,0,0,1,0,0,  1,0,0,0,0,1,0,  1,0,0,0,0,1,0,  0,1,0,0,0,1,0},
       {0,1,1,1,0,0,0,  1,0,0,0,0,1,0,  1,0,0,0,0,1,0,  0,0,1,1,1,0,0} } };

volatile long far *clock = (long far *)CLOCK;
long sync;

int f = 112, d = 1;
int u, v;
char w;
int i, j, k;
double lon = 0, lat = 0;
double x[8 * 28], y[8 * 28], z[8 * 28], r, s, t;

double pi = 3.141592653589793;

/******************************************************************** blit */
void blit(void)
{
   /* Wait for clock (18.2fps) */
#ifdef DISABLEVSYNC
   while( sync == *clock );
   sync = *clock;
#else
   while(inp(986) & 8);
   while(!(inp(986) & 8));
#endif

   /* Write to video memory */
   for(j = 0; j < 50; j += 2)
   {
      for(i = 0; i < 80; i++)
      {
         video[80 * (j / 2) + i] = palette[(screen[j * 80 + i] * 4) |
                                           screen[(j + 1) * 80 + i] ];
      }
   }

} /* blit() */

/****************************************************************** render */
void render(void)
{
   /* Clear screen */
   for(i = 0; i < 4000;)
      screen[i++] = 0;

   /* Calculate coordinates */
   k = 0;
   for(i = 0; i < 8; i++)
   {
      r = sin((i - 3.5) * pi / 50 + pi / 4);
      for(j = 0; j < 28; j++)
      {
         x[k] = r * cos(lat + j * pi / 25);
         z[k] = r * sin(lat + j * pi / 25);
         y[k] = cos((i - 3.5) * pi / 50 + pi / 4);
         k++;
      }
   }
   r = sin(lon);
   s = cos(lon);
   for(i = 0; i < 8 * 28; i++)
   {
      t = y[i];
      y[i] = s * y[i] - r * z[i];
      z[i] = s * z[i] + r * t;
   }

   /* Draw points */
   k = 0;
   for(i = 0; i < 8; i++)
   {
      for(j = 0; j < 28; j++)
      {
         if( (w = (f > 4 * j) ? image[0][i][j] : image[1][i][j]) > 0 )
         {
            u = (int)(1900 * x[k] / (100 * z[k] + 115) + 40);
            v = (int)(1900 * y[k] / (100 * z[k] + 115) + 25);

            if( v >= 0 && v < 50 )
               screen[v * 80 + u] = w;
         }
         k++;
      }
   }

   /* Animate */
   lon = fmod(lon + pi / 61, 2 * pi);
   lat = fmod(lat + pi / 79, 2 * pi);

   f += d;
   if( d > 0 )
   {
      if( f > 315 )
         d = -1;
   }
   else
   {
      if( f < -285 )
         d = 1;
   }

   /* Redraw screen */
   blit();

} /* render() */


/******************************************************************** main */
void cdecl main(void)
{
   /* Save screen */
   for(i = 0; i < 2000;)
      OldScreen[i++] = video[i];

   /* Loop until keypress */
   while( !kbhit() )
      render();


   /* Restore screen */
   for(i = 0; i < 2000;)
      video[i++] = OldScreen[i];

   /* Clear keystroke */
   if( !getch() )
      getch();

} /* main() */