Original 5.40

1 files changed, 794 insertions, 0 deletions

diff --git a/hacks/epicycle.c b/hacks/epicycle.c
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+++ b/hacks/epicycle.c
@@ -0,0 +1,794 @@
+/* epicycle --- The motion of a body with epicycles, as in the pre-Copernican
+ * cosmologies.
+ *
+ * Copyright (c) 1998  James Youngman <jay@gnu.org>
+ * 
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or 
+ * implied warranty.
+ */
+
+/* Standard C headers; screenhack.h assumes that these have already
+ * been included if required -- for example, it defines M_PI if not
+ * already defined.
+ */
+#include <float.h>
+#include <math.h>
+
+
+#include "screenhack.h"
+#include "erase.h"
+
+/* MIT-SHM headers omitted; this screenhack doesn't use it */
+
+
+
+/*********************************************************/
+/******************** MAGIC CONSTANTS ********************/
+/*********************************************************/
+#define MIN_RADIUS (5)		/* smallest allowable circle radius */
+#define FILL_PROPORTION (0.9)	/* proportion of screen to fill by scaling. */
+/*********************************************************/
+/***************** END OF MAGIC CONSTANTS ****************/
+/*********************************************************/
+
+
+
+#define FULLCIRCLE (2.0 * M_PI)	/* radians in a circle. */
+
+
+/* Some of these resource values here are hand-tuned to give a
+ * pleasing variety of interesting shapes.  These are not the only
+ * good settings, but you may find you need to change some as a group
+ * to get pleasing figures.
+ */
+static const char *epicycle_defaults [] = {
+  ".background:	black",
+  ".foreground:	white",
+  "*fpsSolid:	true",
+  "*colors:	100",
+  "*color0:	red",
+  "*delay:	20000",
+  "*holdtime:	2",
+  "*lineWidth:	4",
+  "*minCircles:  2",
+  "*maxCircles:  10",
+  "*minSpeed:	0.003",
+  "*maxSpeed:	0.005",
+  "*harmonics:	8",
+  "*timestep:	1.0",
+  "*timestepCoarseFactor: 1.0", /* no option for this resource. */
+  "*divisorPoisson: 0.4",
+  "*sizeFactorMin: 1.05",
+  "*sizeFactorMax: 2.05",
+#ifdef HAVE_MOBILE
+  "*ignoreRotation: True",
+#endif
+  0
+};
+
+/* options passed to this program */
+static XrmOptionDescRec epicycle_options [] = {
+  { "-color0",		".color0",	  XrmoptionSepArg, 0 },
+  { "-colors",		".colors",	  XrmoptionSepArg, 0 },
+  { "-colours",		".colors",	  XrmoptionSepArg, 0 },
+  { "-foreground",	".foreground",	  XrmoptionSepArg, 0 },
+  { "-delay",		".delay",	  XrmoptionSepArg, 0 },
+  { "-holdtime",	".holdtime",	  XrmoptionSepArg, 0 },
+  { "-linewidth",	".lineWidth",	  XrmoptionSepArg, 0 },
+  { "-min_circles",	".minCircles",	  XrmoptionSepArg, 0 },
+  { "-max_circles",	".maxCircles",	  XrmoptionSepArg, 0 },
+  { "-min_speed",	".minSpeed",	  XrmoptionSepArg, 0 },
+  { "-max_speed",	".maxSpeed",	  XrmoptionSepArg, 0 },
+  { "-harmonics",	".harmonics",	  XrmoptionSepArg, 0 },
+  { "-timestep",	".timestep",	  XrmoptionSepArg, 0 },
+  { "-divisor_poisson",".divisorPoisson",XrmoptionSepArg, 0 },
+  { "-size_factor_min", ".sizeFactorMin", XrmoptionSepArg, 0 },
+  { "-size_factor_max", ".sizeFactorMax", XrmoptionSepArg, 0 },
+  { 0, 0, 0, 0 }
+};
+
+
+/* Each circle is centred on a point on the rim of another circle.
+ */
+struct tagCircle
+{
+  long radius;			/* in pixels */
+  double w;			/* position (radians ccw from x-axis) */
+  double initial_w;		/* starting position */
+  double wdot;			/* rotation rate (change in w per iteration) */
+  int    divisor;
+
+  struct tagCircle *pchild;
+};
+typedef struct tagCircle Circle;
+
+
+struct tagBody			/* a body that moves on a system of circles. */
+{
+  int x_origin, y_origin;
+  int x, y;
+  int old_x, old_y;
+  int current_color;		/* pixel index into colors[] */
+  Circle *epicycles;		/* system of circles on which it moves. */
+  struct tagBody *next;		/* next in list. */
+};
+typedef struct tagBody Body;
+
+
+struct state {
+   Display *dpy;
+   Window window;
+   GC color0;
+   int width, height;
+   int x_offset, y_offset;
+   int unit_pixels;
+   unsigned long bg;
+   Colormap cmap;
+   int restart;
+   double wdot_max;
+   XColor *colors;
+   int ncolors;
+   int color_shift_pos;	/* how far we are towards that. */
+   double colour_cycle_rate;
+   int harmonics;
+   double divisorPoisson;
+   double sizeFactorMin;
+   double sizeFactorMax;
+   int minCircles;
+   int maxCircles;
+
+   Bool done;
+
+   long L;
+   double T, timestep, circle, timestep_coarse;
+   int delay;
+   int uncleared;
+   int holdtime;
+   int xmax, xmin, ymax, ymin;
+   Body *pb0;
+   double xtime;
+   eraser_state *eraser;
+};
+
+
+
+/* Determine the GCD of two numbers using Euclid's method.  The other
+ * possible algorighm is Stein's method, but it's probably only going
+ * to be much faster on machines with no divide instruction, like the
+ * ARM and the Z80.  The former is very fast anyway and the latter
+ * probably won't run X clients; in any case, this calculation is not
+ * the bulk of the computational expense of the program.  I originally
+ * tried using Stein's method, but I wanted to remove the gotos.  Not
+ * wanting to introduce possible bugs, I plumped for Euclid's method
+ * instead.  Lastly, Euclid's algorithm is preferred to the
+ * generalisation for N inputs.
+ *
+ * See Knuth, section 4.5.2.
+ */
+static int
+gcd(int u, int v)		/* Euclid's Method */
+{
+  /* If either operand of % is negative, the sign of the result is
+   * implementation-defined.  See section 6.3.5 "Multiplicative
+   * Operators" of the ANSI C Standard (page 46 [LEFT HAND PAGE!] of
+   * "Annotated C Standard", Osborne, ISBN 0-07-881952-0).
+   */
+  if (u < 0) u = -u;
+  if (v < 0) v = -v;
+  
+  while (0 != v)
+    {
+      int r;
+      r = u % v;
+      u = v;
+      v = r;
+    }
+  return u;
+}
+
+/* Determine the Lowest Common Multiple of two integers, using
+ * Euclid's Proposition 34, as explained in Knuth's The Art of
+ * Computer Programming, Vol 2, section 4.5.2.
+ */
+static int
+lcm(int u, int v)
+{
+  return u / gcd(u,v) * v;
+}
+
+static long 
+random_radius(struct state *st, double scale)	
+{
+  long r;
+
+  r = frand(scale) * st->unit_pixels/2; /* for frand() see utils/yarandom.h */
+  if (r < MIN_RADIUS)
+    r = MIN_RADIUS;
+  return r;
+}
+
+
+static long
+random_divisor(struct state *st)
+{
+  int divisor = 1;
+  int sign;
+
+  while (frand(1.0) < st->divisorPoisson && divisor <= st->harmonics)
+    {
+      ++divisor;
+    }
+  sign = (frand(1.0) < 0.5) ? +1 : -1;
+  return sign * divisor;
+}
+
+
+/* Construct a circle or die.
+ */
+static Circle *
+new_circle(struct state *st, double scale)
+{
+  Circle *p = malloc(sizeof(Circle));
+  
+  p->radius = random_radius(st, scale);
+  p->w = p->initial_w = 0.0;
+  p->divisor = random_divisor(st);
+  p->wdot = st->wdot_max / p->divisor;
+  p->pchild = NULL;
+  
+  return p;
+}
+
+static void delete_circle(Circle *p)
+{
+  free(p);
+}
+
+static void 
+delete_circle_chain(Circle *p)
+{
+  while (p)
+    {
+      Circle *q = p->pchild;
+      delete_circle(p);
+      p = q;
+    }
+}
+
+static Circle *
+new_circle_chain(struct state *st)
+{
+  Circle *head;
+  double scale = 1.0, factor;
+  int n;
+
+  /* Parent circles are larger than their children by a factor of at
+   * least FACTOR_MIN and at most FACTOR_MAX.
+   */
+  factor = st->sizeFactorMin + frand(st->sizeFactorMax - st->sizeFactorMin);
+  
+  /* There are between minCircles and maxCircles in each figure.
+   */
+  if (st->maxCircles == st->minCircles)
+    n = st->minCircles;            /* Avoid division by zero. */
+  else
+    n = st->minCircles + random() % (st->maxCircles - st->minCircles);
+  
+  head = NULL;
+  while (n--)
+    {
+      Circle *p = new_circle(st, scale);
+      p->pchild = head;
+      head = p;
+
+      scale /= factor;
+    }
+  return head;
+}
+
+static void
+assign_random_common_w(Circle *p)
+{
+  double w_common = frand(FULLCIRCLE);	/* anywhere on the circle */
+  while (p)
+    {
+      p->initial_w = w_common;
+      p = p->pchild;
+    }
+}
+
+static Body *
+new_body(struct state *st)
+{
+  Body *p = malloc(sizeof(Body));
+  if (!p) abort();
+  p->epicycles = new_circle_chain(st);
+  p->current_color = 0;		/* ?? start them all on different colors? */
+  p->next = NULL;
+  p->x = p->y = 0;
+  p->old_x = p->old_y = 0;
+  p->x_origin = p->y_origin = 0;
+
+  /* Start all the epicycles at the same w value to make it easier to
+   * figure out at what T value the cycle is closed.   We don't just fix
+   * the initial W value because that makes all the patterns tend to 
+   * be symmetrical about the X axis.
+   */
+  assign_random_common_w(p->epicycles);
+  return p;
+}
+
+static void
+delete_body(Body *p)
+{
+  delete_circle_chain(p->epicycles);
+  free(p);
+}
+
+
+static void 
+draw_body(struct state *st, Body *pb, GC gc)
+{
+  XDrawLine(st->dpy, st->window, gc, pb->old_x, pb->old_y, pb->x, pb->y);
+}
+
+static long
+compute_divisor_lcm(Circle *p)
+{
+  long l = 1;
+  
+  while (p)
+    {
+      l = lcm(l, p->divisor);
+      p = p->pchild;
+    }
+  return l;
+}
+
+	      
+/* move_body()
+ *
+ * Calculate the position for the body at time T.  We work in double 
+ * rather than int to avoid the cumulative errors that would be caused
+ * by the rounding implicit in an assignment to int.
+ */
+static void
+move_body(Body *pb, double t)
+{
+  Circle *p;
+  double x, y;
+
+  pb->old_x = pb->x;
+  pb->old_y = pb->y;
+  
+  x = pb->x_origin;
+  y = pb->y_origin;
+  
+  for (p=pb->epicycles; NULL != p; p=p->pchild)
+    {
+      /* angular pos = initial_pos + time * angular speed */
+      /* but this is an angular position, so modulo FULLCIRCLE. */
+      p->w = fmod(p->initial_w + (t * p->wdot), FULLCIRCLE);
+      
+      x += (p->radius * cos(p->w));
+      y += (p->radius * sin(p->w));
+    }
+  
+  pb->x = (int)x;
+  pb->y = (int)y;
+}
+
+static int
+colour_init(struct state *st, XWindowAttributes *pxgwa)
+{
+  XGCValues gcv;
+
+#if 0
+  int H = random() % 360;	/* colour choice from attraction.c. */
+  double S1 = 0.25;
+  double S2 = 1.00;
+  double V = frand(0.25) + 0.75;
+  int line_width = 0;
+#endif
+
+  int retval = 1;
+  unsigned long valuemask = 0L;
+  unsigned long fg;
+  
+  /* Free any already allocated colors...
+   */
+  if (st->colors)
+    {
+      free_colors(pxgwa->screen, st->cmap, st->colors, st->ncolors);
+      st->colors = 0;
+      st->ncolors = 0;
+    }
+	
+  st->ncolors = get_integer_resource (st->dpy, "colors", "Colors");
+  if (0 == st->ncolors)		/* English spelling? */
+    st->ncolors = get_integer_resource (st->dpy, "colours", "Colors");
+  
+  if (st->ncolors < 2)
+    st->ncolors = 2;
+  if (st->ncolors <= 2)
+    mono_p = True;
+  st->colors = 0;
+
+  if (!mono_p)
+    {
+      st->colors = (XColor *) malloc(sizeof(*st->colors) * (st->ncolors+1));
+      if (!st->colors) abort();
+	  
+      make_smooth_colormap (pxgwa->screen, pxgwa->visual, st->cmap,
+                            st->colors, &st->ncolors,
+			    True, /* allocate */
+			    False, /* not writable */
+			    True); /* verbose (complain about failure) */
+      if (st->ncolors <= 2)
+	{
+	  if (st->colors)
+	    free (st->colors);
+	  st->colors = 0;
+	  mono_p = True;
+	}
+    }
+
+  
+  st->bg = get_pixel_resource (st->dpy, st->cmap, "background", "Background");
+
+  /* Set the line width
+   */
+  gcv.line_width = get_integer_resource (st->dpy, "lineWidth", "Integer");
+  if (gcv.line_width)
+    {
+      valuemask |= GCLineWidth;
+
+      gcv.join_style = JoinRound;
+      gcv.cap_style = CapRound;
+	  
+      valuemask |= (GCCapStyle | GCJoinStyle);
+    }
+  
+
+  /* Set the drawing function.
+   */
+  gcv.function = GXcopy;
+  valuemask |= GCFunction;
+  
+  /* Set the foreground.
+   */
+/*  if (mono_p)*/
+    fg = get_pixel_resource (st->dpy, st->cmap, "foreground", "Foreground");
+/* WTF?
+else
+    fg = st->bg ^ get_pixel_resource (st->dpy, st->cmap, ("color0"), "Foreground"); 
+*/
+  gcv.foreground = fg;
+  valuemask |= GCForeground;
+
+  /* Actually create the GC.
+   */
+  st->color0 = XCreateGC (st->dpy, st->window, valuemask, &gcv);
+  
+  return retval;
+}
+
+
+
+
+static void
+setup(struct state *st)
+{
+  XWindowAttributes xgwa;
+  
+  XGetWindowAttributes (st->dpy, st->window, &xgwa);
+  st->cmap = xgwa.colormap;
+
+  st->width = xgwa.width;
+  st->height = xgwa.height;
+  st->x_offset = st->width / 2;
+  st->y_offset = st->height / 2;
+  st->unit_pixels = st->width < st->height ? st->width : st->height;
+
+  {
+    if (!st->done)
+      {
+	colour_init(st, &xgwa);
+	st->done = True;
+      }
+  }
+}
+
+
+static void
+color_step(struct state *st, Body *pb, double frac)
+{
+  if (!mono_p)
+    {
+      int newshift = st->ncolors * fmod(frac * st->colour_cycle_rate, 1.0);
+      if (newshift != st->color_shift_pos)
+	{
+	  pb->current_color = newshift;
+	  XSetForeground (st->dpy, st->color0, st->colors[pb->current_color].pixel);
+	  st->color_shift_pos = newshift;
+	}
+    }
+}
+
+
+#if 0
+static long
+distance(long x1, long y1, long x2, long y2)
+{
+  long dx, dy;
+
+  dx = x2 - x1;
+  dy = y2 - y1;
+  return dx*dx + dy*dy;
+}
+
+static int poisson_irand(double p)
+{
+  int r = 1;
+  while (fabs(frand(1.0)) < p)
+    ++r;
+  return r < 1 ? 1 : r;
+}
+#endif
+
+static void
+precalculate_figure(Body *pb,
+		    double this_xtime, double step,
+		    int *x_max, int *y_max,
+		    int *x_min, int *y_min)
+{
+  double t;
+  
+  move_body(pb, 0.0); /* move once to avoid initial line from origin */
+  *x_min = *x_max = pb->x;
+  *y_min = *y_max = pb->y;
+  
+  for (t=0.0; t<this_xtime; t += step)
+    {
+      move_body(pb, t); /* move once to avoid initial line from origin */
+      if (pb->x > *x_max)
+	*x_max = pb->x;
+      if (pb->x < *x_min)
+	*x_min = pb->x;
+      if (pb->y > *y_max)
+	*y_max = pb->y;
+      if (pb->y < *y_min)
+	*y_min = pb->y;
+    }
+}
+
+static int i_max(int a, int b)
+{
+  return (a>b) ? a : b;
+}
+
+static void rescale_circles(struct state *st, Body *pb,
+			    int x_max, int y_max,
+			    int x_min, int y_min)
+{
+  double xscale, yscale, scale;
+  double xm, ym;
+  
+  x_max -= st->x_offset;
+  x_min -= st->x_offset;
+  y_max -= st->y_offset;
+  y_min -= st->y_offset;
+
+  x_max = i_max(x_max, -x_min);
+  y_max = i_max(y_max, -y_min);
+
+
+  xm = st->width / 2.0;
+  ym = st->height / 2.0;
+  if (x_max > xm)
+    xscale = xm / x_max;
+  else
+    xscale = 1.0;
+  if (y_max > ym)
+    yscale = ym / y_max;
+  else
+    yscale = 1.0;
+
+  if (xscale < yscale)		/* wider than tall */
+    scale = xscale;		/* ensure width fits onscreen */
+  else
+    scale = yscale;		/* ensure height fits onscreen */
+
+
+  scale *= FILL_PROPORTION;	/* only fill FILL_PROPORTION of screen */
+  if (scale < 1.0)		/* only reduce, don't enlarge. */
+    {
+      Circle *p;
+      for (p=pb->epicycles; p; p=p->pchild)
+	{
+	  p->radius *= scale;
+	}
+    }
+  else
+    {
+      printf("enlarge by x%.2f skipped...\n", scale);
+    }
+
+  if (st->width > st->height * 5 ||  /* window has weird aspect */
+      st->height > st->width * 5)
+    {
+      Circle *p;
+      double r = (st->width > st->height
+                  ? st->width / (double) st->height
+                  : st->height / (double) st->width);
+      for (p=pb->epicycles; p; p=p->pchild)
+        p->radius *= r;
+    }
+}
+
+
+/* angular speeds of the circles are harmonics of a fundamental
+ * value.  That should please the Pythagoreans among you... :-)
+ */
+static double 
+random_wdot_max(struct state *st)
+{
+  /* Maximum and minimum values for the choice of wdot_max.  Possible
+   * epicycle speeds vary from wdot_max to (wdot_max * harmonics).
+   */
+  double minspeed, maxspeed;
+  minspeed = get_float_resource(st->dpy, "minSpeed", "Double");
+  maxspeed = get_float_resource(st->dpy, "maxSpeed", "Double");
+  return st->harmonics * (minspeed + FULLCIRCLE * frand(maxspeed-minspeed));
+}
+
+
+static void *
+epicycle_init (Display *disp, Window win)
+{
+  struct state *st = (struct state *) calloc (1, sizeof(*st));
+  st->dpy = disp;
+  st->window = win;
+
+  st->holdtime = get_integer_resource (st->dpy, "holdtime", "Integer");
+
+  st->circle = FULLCIRCLE;
+  
+  XClearWindow(st->dpy, st->window);
+  st->uncleared = 0;
+  st->restart = 1;
+  
+  st->delay = get_integer_resource (st->dpy, "delay", "Integer");
+  st->harmonics = get_integer_resource(st->dpy, "harmonics", "Integer");
+  st->divisorPoisson = get_float_resource(st->dpy, "divisorPoisson", "Double");
+  
+  st->timestep = get_float_resource(st->dpy, "timestep", "Double");
+  st->timestep_coarse = st->timestep *
+    get_float_resource(st->dpy, "timestepCoarseFactor", "Double");
+  
+  st->sizeFactorMin = get_float_resource(st->dpy, "sizeFactorMin", "Double");
+  st->sizeFactorMax = get_float_resource(st->dpy, "sizeFactorMax", "Double");
+
+  st->minCircles = get_integer_resource (st->dpy, "minCircles", "Integer");
+  st->maxCircles = get_integer_resource (st->dpy, "maxCircles", "Integer");
+
+  st->xtime = 0; /* is this right? */
+
+  return st;
+}
+
+static unsigned long
+epicycle_draw (Display *dpy, Window window, void *closure)
+{
+  struct state *st = (struct state *) closure;
+  int this_delay = st->delay;
+
+  if (st->eraser) {
+    st->eraser = erase_window (st->dpy, st->window, st->eraser);
+    return 10000;
+  }
+
+  if (st->restart)
+    {
+      setup(st);
+      st->restart = 0;
+
+      /* Flush any outstanding events; this has the side effect of
+       * reducing the number of "false restarts"; resdtarts caused by
+       * one event (e.g. ConfigureNotify) followed by another
+       * (e.g. Expose).
+       */
+	  
+      st->wdot_max = random_wdot_max(st);
+	  
+      if (st->pb0)
+        {
+          delete_body(st->pb0);
+          st->pb0 = NULL;
+        }
+      st->pb0 = new_body(st);
+      st->pb0->x_origin = st->pb0->x = st->x_offset;
+      st->pb0->y_origin = st->pb0->y = st->y_offset;
+
+      if (st->uncleared)
+        {
+          st->eraser = erase_window (st->dpy, st->window, st->eraser);
+          st->uncleared = 0;
+        }
+
+      precalculate_figure(st->pb0, st->xtime, st->timestep_coarse,
+                          &st->xmax, &st->ymax, &st->xmin, &st->ymin);
+
+      rescale_circles(st, st->pb0, st->xmax, st->ymax, st->xmin, st->ymin);
+      
+      move_body(st->pb0, 0.0); /* move once to avoid initial line from origin */
+      move_body(st->pb0, 0.0); /* move once to avoid initial line from origin */
+
+      
+      st->T = 0.0;			/* start at time zero. */
+
+      st->L = compute_divisor_lcm(st->pb0->epicycles);
+      
+      st->colour_cycle_rate = labs(st->L);
+      
+      st->xtime = fabs(st->L * st->circle / st->wdot_max);
+
+      if (st->colors)				/* (colors==NULL) if mono_p */
+        XSetForeground (st->dpy, st->color0, st->colors[st->pb0->current_color].pixel);
+    }
+
+
+  color_step(st, st->pb0, st->T/st->xtime );
+  draw_body(st, st->pb0, st->color0);
+  st->uncleared = 1;
+
+	  
+  /* Check if the figure is complete...*/
+  if (st->T > st->xtime)
+    {
+      this_delay = st->holdtime * 1000000;
+      st->restart = 1;	/* begin new figure. */
+    }
+	  
+
+
+  st->T += st->timestep;
+  move_body(st->pb0, st->T);
+
+  return this_delay;
+}
+
+static void
+epicycle_reshape (Display *dpy, Window window, void *closure, 
+                 unsigned int w, unsigned int h)
+{
+  struct state *st = (struct state *) closure;
+  st->restart = 1;
+}
+
+static Bool
+epicycle_event (Display *dpy, Window window, void *closure, XEvent *e)
+{
+  struct state *st = (struct state *) closure;
+  if (screenhack_event_helper (dpy, window, e))
+    {
+      st->restart = 1;
+      return True;
+    }
+
+  return False;
+}
+
+static void
+epicycle_free (Display *dpy, Window window, void *closure)
+{
+  struct state *st = (struct state *) closure;
+  free (st);
+}
+
+XSCREENSAVER_MODULE ("Epicycle", epicycle)