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/* erase.c: Erase the screen in various more or less interesting ways.
 * (c) 1997 by Johannes Keukelaar <johannes@nada.kth.se>
 * Permission to use in any way granted. Provided "as is" without expressed
 * or implied warranty. NO WARRANTY, NO EXPRESSION OF SUITABILITY FOR ANY
 * PURPOSE. (I.e.: Use in any way, but at your own risk!)
 */
#include <stdio.h>
//#include <unistd.h>
#define usleep(x)
#include <stdlib.h>
#include <math.h>
#define MWINCLUDECOLORS
#include "nano-X.h"
#include "maze.h"
 
#undef countof
#define countof(x) (sizeof(x)/sizeof(*(x)))
 
typedef void (*Eraser) (int width, int height, int delay, int granularity);
typedef int Bool;
 
static void
random_lines (int width, int height, int delay, int granularity)
{
  Bool horiz_p = (random() & 1);
  int max = (horiz_p ? height : width);
  int *lines = (int *) calloc(max, sizeof(*lines));
  int i;
 
  for (i = 0; i < max; i++)
    lines[i] = i;
 
  for (i = 0; i < max; i++)
    {
      int t, r;
      t = lines[i];
      r = random() % max;
      lines[i] = lines[r];
      lines[r] = t;
    }
 
  for (i = 0; i < max; i++)
    { 
      if (horiz_p)
	GrLine (wid, erase_gc, 0, lines[i], width, lines[i]);
      else
	GrLine (wid, erase_gc, lines[i], 0, lines[i], height);
 
      wait_sync ();
      if (delay > 0 && ((i % granularity) == 0))
	usleep (delay * granularity);
    }
  free(lines);
}
 
 
static void
venetian (int width, int height, int delay, int granularity)
{
  Bool horiz_p = (random() & 1);
  Bool flip_p = (random() & 1);
  int max = (horiz_p ? height : width);
  int *lines = (int *) calloc(max, sizeof(*lines));
  int i, j;
 
  granularity /= 6;
 
  j = 0;
  for (i = 0; i < max*2; i++)
    {
      int line = ((i / 16) * 16) - ((i % 16) * 15);
      if (line >= 0 && line < max)
	lines[j++] = (flip_p ? max - line : line);
    }
 
  for (i = 0; i < max; i++)
    { 
      if (horiz_p)
	GrLine (wid, erase_gc, 0, lines[i], width, lines[i]);
      else
	GrLine (wid, erase_gc, lines[i], 0, lines[i], height);
 
      wait_sync ();
      if (delay > 0 && ((i % granularity) == 0))
	usleep (delay * granularity);
    }
  free(lines);
}
 
 
static void
triple_wipe (int width, int height, int delay, int granularity)
{
  Bool flip_x = random() & 1;
  Bool flip_y = random() & 1;
  int max = width + (height / 2);
  int *lines = (int *)calloc(max, sizeof(int));
  int i;
 
  for(i = 0; i < width/2; i++)
    lines[i] = i*2+height;
  for(i = 0; i < height/2; i++)
    lines[i+width/2] = i*2;
  for(i = 0; i < width/2; i++)
    lines[i+width/2+height/2] = width-i*2-(width%2?0:1)+height;
 
  granularity /= 6;
 
  for (i = 0; i < max; i++)
    { 
      int x, y, x2, y2;
      if (lines[i] < height)
	x = 0, y = lines[i], x2 = width, y2 = y;
      else
	x = lines[i]-height, y = 0, x2 = x, y2 = height;
 
      if (flip_x)
	x = width-x, x2 = width-x2;
      if (flip_y)
	y = height-y, y2 = height-y2;
 
      GrLine (wid, erase_gc, x, y, x2, y2);
      wait_sync ();
      if (delay > 0 && ((i % granularity) == 0))
	usleep (delay*granularity);
    }
  free(lines);
}
 
 
static void
quad_wipe (int width, int height, int delay, int granularity)
{
  Bool flip_x = random() & 1;
  Bool flip_y = random() & 1;
  int max = width + height;
  int *lines = (int *)calloc(max, sizeof(int));
  int i;
 
  granularity /= 3;
 
  for (i = 0; i < max/4; i++)
    {
      lines[i*4]   = i*2;
      lines[i*4+1] = height-i*2-(height%2?0:1);
      lines[i*4+2] = height+i*2;
      lines[i*4+3] = height+width-i*2-(width%2?0:1);
    }
 
  for (i = 0; i < max; i++)
    { 
      int x, y, x2, y2;
      if (lines[i] < height)
	x = 0, y = lines[i], x2 = width, y2 = y;
      else
	x = lines[i]-height, y = 0, x2 = x, y2 = height;
 
      if (flip_x)
	x = width-x, x2 = width-x2;
      if (flip_y)
	y = height-y, y2 = height-y2;
 
      GrLine (wid, erase_gc, x, y, x2, y2);
      wait_sync ();
      if (delay > 0 && ((i % granularity) == 0))
	usleep (delay*granularity);
    }
  free(lines);
}
 
#if 0
static void
circle_wipe (int width, int height, int delay, int granularity)
{
  int full = 360 * 64;
  int inc = full / 64;
  int start = random() % full;
  int rad = (width > height ? width : height);
  int i;
  if (random() & 1)
    inc = -inc;
  for (i = (inc > 0 ? 0 : full);
       (inc > 0 ? i < full : i > 0);
       i += inc)
    {
      GrArc(wid, erase_gc,
	       (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (i+start) % full, inc);
      usleep (delay*granularity);
    }
}
#endif
 
#if 0
static void
three_circle_wipe (int width, int height, int delay, int granularity)
{
  int i;
  int full = 360 * 64;
  int q = full / 6;
  int q2 = q * 2;
  int inc = full / 240;
  int start = random() % q;
  int rad = (width > height ? width : height);
 
  for (i = 0; i < q; i += inc)
    {
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start+i) % full, inc);
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start-i) % full, -inc);
 
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start+q2+i) % full, inc);
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start+q2-i) % full, -inc);
 
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start+q2+q2+i) % full, inc);
      GrArc(wid, erase_gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
	       (start+q2+q2-i) % full, -inc);
 
      wait_sync ();
      usleep (delay*granularity);
    }
}
#endif
 
static void
squaretate (int width, int height, int delay, int granularity)
{
  int steps = (((width > height ? width : width) * 2) / granularity);
  int i;
  Bool flip = random() & 1;
 
#define DRAW() \
      if (flip) { \
	points[0].x = width-points[0].x; \
	points[1].x = width-points[1].x; \
        points[2].x = width-points[2].x; } \
      GrFillPoly (wid, erase_gc, 3, points)
 
  for (i = 0; i < steps; i++)
    {
      GR_POINT points [3];
      points[0].x = 0;
      points[0].y = 0;
      points[1].x = width;
      points[1].y = 0;
      points[2].x = 0;
      points[2].y = points[0].y + ((i * height) / steps);
      DRAW();
 
      points[0].x = 0;
      points[0].y = 0;
      points[1].x = 0;
      points[1].y = height;
      points[2].x = ((i * width) / steps);
      points[2].y = height;
      DRAW();
 
      points[0].x = width;
      points[0].y = height;
      points[1].x = 0;
      points[1].y = height;
      points[2].x = width;
      points[2].y = height - ((i * height) / steps);
      DRAW();
 
      points[0].x = width;
      points[0].y = height;
      points[1].x = width;
      points[1].y = 0;
      points[2].x = width - ((i * width) / steps);
      points[2].y = 0;
      DRAW();
 
      wait_sync ();
      if (delay > 0)
	usleep (delay * granularity);
   }
#undef DRAW
}
 
 
/* from Frederick Roeber <roeber@netscape.com> */
static void
fizzle (int width, int height, int delay, int granularity)
{
  /* These dimensions must be prime numbers.  They should be roughly the
     square root of the width and height. */
# define BX 31
# define BY 31
# define SIZE (BX*BY)
 
  int array[SIZE];
  int i, j;
  GR_POINT *skews;
  int nx, ny;
 
  /* Distribute the numbers [0,SIZE) randomly in the array */
  {
    int indices[SIZE];
 
    for( i = 0; i < SIZE; i++ ) {
      array[i] = -1;
      indices[i] = i;
    } 
 
    for( i = 0; i < SIZE; i++ ) {
      j = random()%(SIZE-i);
      array[indices[j]] = i;
      indices[j] = indices[SIZE-i-1];
    }
  }
 
  /* nx, ny are the number of cells across and down, rounded up */
  nx = width  / BX + (0 == (width %BX) ? 0 : 1);
  ny = height / BY + (0 == (height%BY) ? 0 : 1);
  skews = (GR_POINT *)malloc(sizeof(GR_POINT) * (nx*ny));
  if( (GR_POINT *)0 != skews ) {
    for( i = 0; i < nx; i++ ) {
      for( j = 0; j < ny; j++ ) {
        skews[j * nx + i].x = random()%BX;
        skews[j * nx + i].y = random()%BY;
      }
    }
  }
 
# define SKEWX(cx, cy) (((GR_POINT *)0 == skews)?0:skews[cy*nx + cx].x)
# define SKEWY(cx, cy) (((GR_POINT *)0 == skews)?0:skews[cy*nx + cx].y)
 
  for( i = 0; i < SIZE; i++ ) {
    int x = array[i] % BX;
    int y = array[i] / BX;
 
    {
      int iy, cy;
      for( iy = 0, cy = 0; iy < height; iy += BY, cy++ ) {
        int ix, cx;
        for( ix = 0, cx = 0; ix < width; ix += BX, cx++ ) {
          int xx = ix + (SKEWX(cx, cy) + x*((cx%(BX-1))+1))%BX;
          int yy = iy + (SKEWY(cx, cy) + y*((cy%(BY-1))+1))%BY;
          if (xx < width && yy < height)
            GrPoint(wid, erase_gc, xx, yy);
        }
      }
    }
 
    if( (BX-1) == (i%BX) ) {
      wait_sync ();
      usleep (delay*granularity);
    }
  }
 
# undef SKEWX
# undef SKEWY
 
  if( (GR_POINT *)0 != skews ) {
    free(skews);
  }
 
# undef BX
# undef BY
# undef SIZE
}
 
 
/* from Rick Campbell <rick@campbellcentral.org> */
static void
spiral (int width, int height, int delay, int granularity)
{
# define SPIRAL_ERASE_PI_2 (M_PI + M_PI)
# define SPIRAL_ERASE_LOOP_COUNT (10)
# define SPIRAL_ERASE_ARC_COUNT (360.0)
# define SPIRAL_ERASE_ANGLE_INCREMENT (SPIRAL_ERASE_PI_2 /     \
SPIRAL_ERASE_ARC_COUNT)
# define SPIRAL_ERASE_DELAY (0)
 
  double angle;
  int arc_limit;
  int arc_max_limit;
  int length_step;
  GR_POINT points [3];
 
  angle = 0.0;
  arc_limit = 1;
  arc_max_limit = (int) (ceil (sqrt ((width * width) + (height * height)))
                         / 2.0);
  length_step = ((arc_max_limit + SPIRAL_ERASE_LOOP_COUNT - 1) /
                 SPIRAL_ERASE_LOOP_COUNT);
  arc_max_limit += length_step;
  points [0].x = width / 2;
  points [0].y = height / 2;
  points [1].x = points [0].x + length_step;
  points [1].y = points [0].y;
  points [2].x = points [1].x;
  points [2].y = points [1].y;
 
  for (arc_limit = length_step;
       arc_limit < arc_max_limit;
       arc_limit += length_step)
    {
      int arc_length = length_step;
      int length_base = arc_limit;
      for (angle = 0.0; angle < SPIRAL_ERASE_PI_2;
           angle += SPIRAL_ERASE_ANGLE_INCREMENT)
        {
          arc_length = length_base + ((length_step * angle) /
                                      SPIRAL_ERASE_PI_2);
          points [1].x = points [2].x;
          points [1].y = points [2].y;
          points [2].x = points [0].x + (int)(cos (angle) * arc_length);
          points [2].y = points [0].y + (int)(sin (angle) * arc_length);
          GrFillPoly (wid, erase_gc, 3, points);
# if (SPIRAL_ERASE_DELAY != 0)
          usleep (SPIRAL_ERASE_DELAY);
# endif /* (SPIRAL_ERASE_DELAY != 0) */
        }
    }
# undef SPIRAL_ERASE_DELAY
# undef SPIRAL_ERASE_ANGLE_INCREMENT
# undef SPIRAL_ERASE_ARC_COUNT
# undef SPIRAL_ERASE_LOOP_COUNT
# undef SPIRAL_ERASE_PI_2
}
 
 
#undef MAX
#undef MIN
#define MAX(a,b) ((a)>(b)?(a):(b))
#define MIN(a,b) ((a)<(b)?(a):(b))
 
/* from David Bagley <bagleyd@tux.org> */
static void
random_squares(int width, int height, int delay, int granularity)
{
  int randsize = MAX(1, MIN(width, height) / (16 + (random() % 32)));
  int max = (height / randsize + 1) * (width / randsize + 1);
  int *squares = (int *) calloc(max, sizeof (*squares));
  int i;
  int columns = width / randsize + 1;  /* Add an extra for roundoff */
 
  for (i = 0; i < max; i++)
    squares[i] = i;
 
  for (i = 0; i < max; i++)
    {
      int t, r;
      t = squares[i];
      r = random() % max;
      squares[i] = squares[r];
      squares[r] = t;
    }
 
  for (i = 0; i < max; i++)
    {
      GrRect(wid, erase_gc,
		     (squares[i] % columns) * randsize,
		     (squares[i] / columns) * randsize,
		     randsize, randsize);
      wait_sync ();
      if (delay > 0 && ((i % granularity) == 0))
      usleep(delay * granularity);
    }
  free(squares);
}
 
/* I first saw something like this, albeit in reverse, in an early Tetris
   implementation for the Mac.
    -- Torbjörn Andersson <torbjorn@dev.eurotime.se>
 */
 
static void
slide_lines (int width, int height, int delay, int granularity)
{
  int slide_old_x, slide_new_x, clear_x;
  int x, y, dx, dy;
 
  /* This might need some tuning. The idea is to get sensible values no
     matter what the size of the window.
 
     Everything moves at constant speed. Should it accelerate instead? */
 
  granularity *= 2;
 
  dy = MAX (1, height / granularity);
  dx = MAX (1, width / 100);
 
  for (x = 0; x < width; x += dx)
    {
      for (y = 0; y < height; y += dy)
	{
	  if ((y / dy) & 1)
	    {
	      slide_old_x = x;
	      slide_new_x = x + dx;
	      clear_x = x;
	    }
	  else
	    {
	      slide_old_x = dx;
	      slide_new_x = 0;
	      clear_x = width - x - dx;
	    }
 
	  GrCopyArea (wid, erase_gc, slide_old_x, y, width - x - dx,
		     dy, wid, slide_new_x, y, MWROP_SRCCOPY);
	  GrRect (wid, erase_gc, clear_x, y, dx, dy);
	}
 
      wait_sync ();
      usleep(delay * 3);
    }
}
 
static Eraser erasers[] = {
  random_lines,
  venetian,
  triple_wipe,
  quad_wipe,
/*  circle_wipe,
  three_circle_wipe, // needs floating point */
  squaretate,
/*  fizzle, // Too slow */
  random_squares,
  spiral,
  slide_lines,
};
 
 
void
erase_full_window()
{
  int granularity = 25;
  int delay = 0;
  int mode = random() % countof(erasers);
  (*(erasers[mode])) (WINDOW_WIDTH, WINDOW_HEIGHT, delay, granularity);
  GrRect (wid, erase_gc, 0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
  wait_sync ();
}