--- /dev/null
+/* -*- Mode: C; tab-width: 4 -*- */
+/*-
+ * braid --- random braids around a circle and then changes the color in
+ * a rotational pattern
+ */
+
+#if 0
+static const char sccsid[] = "@(#)braid.c 5.00 2000/11/01 xlockmore";
+#endif
+
+/*-
+ * Copyright (c) 1995 by John Neil.
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose and without fee is hereby granted,
+ * provided that the above copyright notice appear in all copies and that
+ * both that copyright notice and this permission notice appear in
+ * supporting documentation.
+ *
+ * This file is provided AS IS with no warranties of any kind. The author
+ * shall have no liability with respect to the infringement of copyrights,
+ * trade secrets or any patents by this file or any part thereof. In no
+ * event will the author be liable for any lost revenue or profits or
+ * other special, indirect and consequential damages.
+ *
+ * Revision History:
+ * 01-Nov-2000: Allocation checks
+ * 10-May-1997: Jamie Zawinski <jwz@jwz.org> compatible with xscreensaver
+ * 01-Sep-1995: color knotted components differently, J. Neil.
+ * 29-Aug-1995: Written. John Neil <neil@math.idbsu.edu>
+ */
+
+#ifdef STANDALONE
+# define MODE_braid
+# define DEFAULTS "*delay: 1000 \n" \
+ "*count: 15 \n" \
+ "*cycles: 100 \n" \
+ "*size: -7 \n" \
+ "*ncolors: 64 \n"
+# define UNIFORM_COLORS
+# define reshape_braid 0
+# define braid_handle_event 0
+# include "xlockmore.h"
+# include "erase.h"
+#else /* STANDALONE */
+# include "xlock.h"
+# define ENTRYPOINT /**/
+#endif /* STANDALONE */
+
+#ifdef MODE_braid
+
+ENTRYPOINT ModeSpecOpt braid_opts =
+{0, (XrmOptionDescRec *) NULL, 0, (argtype *) NULL, (OptionStruct *) NULL};
+
+#ifdef USE_MODULES
+ModStruct braid_description =
+{"braid", "init_braid", "draw_braid", "release_braid",
+ "refresh_braid", "init_braid", (char *) NULL, &braid_opts,
+ 1000, 15, 100, 1, 64, 1.0, "",
+ "Shows random braids and knots", 0, NULL};
+
+#endif
+
+#if defined( COLORROUND ) && defined( COLORCOMP )
+#undef COLORROUND
+#undef COLORCOMP
+#endif
+
+#if !defined( COLORROUND ) && !defined( COLORCOMP )
+#if 0
+/* to color in a circular pattern use COLORROUND */
+#define COLORROUND
+#else
+/* to color by component use COLORCOMP */
+#define COLORCOMP
+#endif
+#endif
+
+#define MAXLENGTH 50 /* the maximum length of a braid word */
+#define MINLENGTH 8 /* the minimum length of a braid word */
+#define MAXSTRANDS 15 /* the maximum number of strands in the braid */
+#define MINSTRANDS 3 /* the minimum number of strands in the braid */
+#define SPINRATE 12.0 /* the rate at which the colors spin */
+
+#define INTRAND(min,max) (NRAND((max+1)-(min))+(min))
+#define FLOATRAND(min,max) ((min)+((double) LRAND()/((double) MAXRAND))*((max)-(min)))
+
+typedef struct {
+ int linewidth;
+ int braidword[MAXLENGTH];
+ int components[MAXSTRANDS];
+ int startcomp[MAXLENGTH][MAXSTRANDS];
+ int nstrands;
+ int braidlength;
+ float startcolor;
+ int center_x;
+ int center_y;
+ float min_radius;
+ float max_radius;
+ float top, bottom, left, right;
+ int age;
+ int color_direction;
+#ifdef STANDALONE
+ eraser_state *eraser;
+#endif
+} braidtype;
+
+static braidtype *braids = (braidtype *) NULL;
+
+static int
+applyword(braidtype * braid, int string, int position)
+{
+ int i, c;
+
+ c = string;
+ for (i = position; i < braid->braidlength; i++) {
+ if (c == ABS(braid->braidword[i]))
+ c--;
+ else if (c == ABS(braid->braidword[i]) - 1)
+ c++;
+ }
+ for (i = 0; i < position; i++) {
+ if (c == ABS(braid->braidword[i]))
+ c--;
+ else if (c == ABS(braid->braidword[i]) - 1)
+ c++;
+ }
+ return c;
+}
+
+#if 0
+static int
+applywordto(braidtype * braid, int string, int position)
+{
+ int i, c;
+
+ c = string;
+ for (i = 0; i < position; i++) {
+ if (c == ABS(braid->braidword[i])) {
+ c--;
+ } else if (c == ABS(braid->braidword[i]) - 1) {
+ c++;
+ }
+ }
+ return c;
+}
+#endif
+
+static int
+applywordbackto(braidtype * braid, int string, int position)
+{
+ int i, c;
+
+ c = string;
+ for (i = position - 1; i >= 0; i--) {
+ if (c == ABS(braid->braidword[i])) {
+ c--;
+ } else if (c == ABS(braid->braidword[i]) - 1) {
+ c++;
+ }
+ }
+ return c;
+}
+
+ENTRYPOINT void
+init_braid(ModeInfo * mi)
+{
+ braidtype *braid;
+ int used[MAXSTRANDS];
+ int i, count, comp, c;
+ float min_length;
+
+ if (braids == NULL) {
+ if ((braids = (braidtype *) calloc(MI_NUM_SCREENS(mi),
+ sizeof (braidtype))) == NULL)
+ return;
+ }
+ braid = &braids[MI_SCREEN(mi)];
+
+ braid->center_x = MI_WIDTH(mi) / 2;
+ braid->center_y = MI_HEIGHT(mi) / 2;
+ braid->age = 0;
+
+ /* jwz: go in the other direction sometimes. */
+ braid->color_direction = ((LRAND() & 1) ? 1 : -1);
+
+#ifndef STANDALONE
+ MI_CLEARWINDOW(mi);
+#endif
+
+ min_length = (braid->center_x > braid->center_y) ?
+ braid->center_y : braid->center_x;
+ braid->min_radius = min_length * 0.30;
+ braid->max_radius = min_length * 0.90;
+
+ if (MI_COUNT(mi) < MINSTRANDS)
+ braid->nstrands = MINSTRANDS;
+ else
+ braid->nstrands = INTRAND(MINSTRANDS,
+ MAX(MIN(MIN(MAXSTRANDS, MI_COUNT(mi)),
+ (int) ((braid->max_radius - braid->min_radius) / 5.0)), MINSTRANDS));
+ braid->braidlength = INTRAND(MINLENGTH, MIN(MAXLENGTH, braid->nstrands * 6));
+
+ for (i = 0; i < braid->braidlength; i++) {
+ braid->braidword[i] =
+ INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
+ if (i > 0)
+ while (braid->braidword[i] == -braid->braidword[i - 1])
+ braid->braidword[i] = INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
+ }
+
+ while (braid->braidword[0] == -braid->braidword[braid->braidlength - 1])
+ braid->braidword[braid->braidlength - 1] =
+ INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
+
+ do {
+ (void) memset((char *) used, 0, sizeof (used));
+ count = 0;
+ for (i = 0; i < braid->braidlength; i++)
+ used[ABS(braid->braidword[i])]++;
+ for (i = 0; i < braid->nstrands; i++)
+ count += (used[i] > 0) ? 1 : 0;
+ if (count < braid->nstrands - 1) {
+ braid->braidword[braid->braidlength] =
+ INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
+ while (braid->braidword[braid->braidlength] ==
+ -braid->braidword[braid->braidlength - 1] &&
+ braid->braidword[0] == -braid->braidword[braid->braidlength])
+ braid->braidword[braid->braidlength] =
+ INTRAND(1, braid->nstrands - 1) * (INTRAND(1, 2) * 2 - 3);
+ braid->braidlength++;
+ }
+ } while (count < braid->nstrands - 1 && braid->braidlength < MAXLENGTH);
+
+ braid->startcolor = (MI_NPIXELS(mi) > 2) ?
+ (float) NRAND(MI_NPIXELS(mi)) : 0.0;
+ /* XSetLineAttributes (display, MI_GC(mi), 2, LineSolid, CapRound,
+ JoinRound); */
+
+ (void) memset((char *) braid->components, 0, sizeof (braid->components));
+ c = 1;
+ comp = 0;
+ braid->components[0] = 1;
+ do {
+ i = comp;
+ do {
+ i = applyword(braid, i, 0);
+ braid->components[i] = braid->components[comp];
+ } while (i != comp);
+ count = 0;
+ for (i = 0; i < braid->nstrands; i++)
+ if (braid->components[i] == 0)
+ count++;
+ if (count > 0) {
+ for (comp = 0; braid->components[comp] != 0; comp++);
+ braid->components[comp] = ++c;
+ }
+ } while (count > 0);
+
+ braid->linewidth = MI_SIZE(mi);
+
+ if (braid->linewidth < 0)
+ braid->linewidth = NRAND(-braid->linewidth) + 1;
+ if (braid->linewidth * braid->linewidth * 8 > MIN(MI_WIDTH(mi), MI_HEIGHT(mi)))
+ braid->linewidth = MIN(1, (int) sqrt((double) MIN(MI_WIDTH(mi), MI_HEIGHT(mi)) / 8));
+ for (i = 0; i < braid->nstrands; i++)
+ if (!(braid->components[i] & 1))
+ braid->components[i] *= -1;
+}
+
+ENTRYPOINT void
+draw_braid(ModeInfo * mi)
+{
+ Display *display = MI_DISPLAY(mi);
+ Window window = MI_WINDOW(mi);
+ int num_points = 500;
+ float t_inc;
+ float theta, psi;
+ float t, r_diff;
+ int i, s;
+ float x_1, y_1, x_2, y_2, r1, r2;
+ float color, color_use = 0.0, color_inc;
+ braidtype *braid;
+
+ if (braids == NULL)
+ return;
+ braid = &braids[MI_SCREEN(mi)];
+
+#ifdef STANDALONE
+ if (braid->eraser) {
+ braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
+ return;
+ }
+#endif
+
+ MI_IS_DRAWN(mi) = True;
+ XSetLineAttributes(display, MI_GC(mi), braid->linewidth,
+ LineSolid,
+ (braid->linewidth <= 3 ? CapButt : CapRound),
+ JoinMiter);
+
+ theta = (2.0 * M_PI) / (float) (braid->braidlength);
+ t_inc = (2.0 * M_PI) / (float) num_points;
+ color_inc = (float) MI_NPIXELS(mi) * braid->color_direction /
+ (float) num_points;
+ braid->startcolor += SPINRATE * color_inc;
+ if (((int) braid->startcolor) >= MI_NPIXELS(mi))
+ braid->startcolor = 0.0;
+
+ r_diff = (braid->max_radius - braid->min_radius) / (float) (braid->nstrands);
+
+ color = braid->startcolor;
+ psi = 0.0;
+ for (i = 0; i < braid->braidlength; i++) {
+ psi += theta;
+ for (t = 0.0; t < theta; t += t_inc) {
+#ifdef COLORROUND
+ color += color_inc;
+ if (((int) color) >= MI_NPIXELS(mi))
+ color = 0.0;
+ color_use = color;
+#endif
+ for (s = 0; s < braid->nstrands; s++) {
+ if (ABS(braid->braidword[i]) == s)
+ continue;
+ if (ABS(braid->braidword[i]) - 1 == s) {
+ /* crosSINFg */
+#ifdef COLORCOMP
+ if (MI_NPIXELS(mi) > 2) {
+ color_use = color + SPINRATE *
+ braid->components[applywordbackto(braid, s, i)] +
+ (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
+ while (((int) color_use) >= MI_NPIXELS(mi))
+ color_use -= (float) MI_NPIXELS(mi);
+ while (((int) color_use) < 0)
+ color_use += (float) MI_NPIXELS(mi);
+ }
+#endif
+#ifdef COLORROUND
+ if (MI_NPIXELS(mi) > 2) {
+ color_use += SPINRATE * color_inc;
+ while (((int) color_use) >= MI_NPIXELS(mi))
+ color_use -= (float) MI_NPIXELS(mi);
+ }
+#endif
+ r1 = braid->min_radius + r_diff * (float) (s);
+ r2 = braid->min_radius + r_diff * (float) (s + 1);
+ if (braid->braidword[i] > 0 ||
+ (FABSF(t - theta / 2.0) > theta / 7.0)) {
+ x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
+ 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
+ COSF(t + psi) + braid->center_x;
+ y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r2 +
+ 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r1)) *
+ SINF(t + psi) + braid->center_y;
+ x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
+ 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
+ COSF(t + t_inc + psi) + braid->center_x;
+ y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r2 +
+ 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r1)) *
+ SINF(t + t_inc + psi) + braid->center_y;
+ if (MI_NPIXELS(mi) > 2)
+ XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
+ else
+ XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
+
+ XDrawLine(display, window, MI_GC(mi),
+ (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
+ }
+#ifdef COLORCOMP
+ if (MI_NPIXELS(mi) > 2) {
+ color_use = color + SPINRATE *
+ braid->components[applywordbackto(braid, s + 1, i)] +
+ (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
+ while (((int) color_use) >= MI_NPIXELS(mi))
+ color_use -= (float) MI_NPIXELS(mi);
+ while (((int) color_use) < 0)
+ color_use += (float) MI_NPIXELS(mi);
+ }
+#endif
+ if (braid->braidword[i] < 0 ||
+ (FABSF(t - theta / 2.0) > theta / 7.0)) {
+ x_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
+ 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
+ COSF(t + psi) + braid->center_x;
+ y_1 = ((0.5 * (1.0 + SINF(t / theta * M_PI - M_PI_2)) * r1 +
+ 0.5 * (1.0 + SINF((theta - t) / theta * M_PI - M_PI_2)) * r2)) *
+ SINF(t + psi) + braid->center_y;
+ x_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
+ 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
+ COSF(t + t_inc + psi) + braid->center_x;
+ y_2 = ((0.5 * (1.0 + SINF((t + t_inc) / theta * M_PI - M_PI_2)) * r1 +
+ 0.5 * (1.0 + SINF((theta - t - t_inc) / theta * M_PI - M_PI_2)) * r2)) *
+ SINF(t + t_inc + psi) + braid->center_y;
+ if (MI_NPIXELS(mi) > 2)
+ XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
+ else
+ XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
+
+ XDrawLine(display, window, MI_GC(mi),
+ (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
+ }
+ } else {
+ /* no crosSINFg */
+#ifdef COLORCOMP
+ if (MI_NPIXELS(mi) > 2) {
+ color_use = color + SPINRATE *
+ braid->components[applywordbackto(braid, s, i)] +
+ (psi + t) / 2.0 / M_PI * (float) MI_NPIXELS(mi);
+ while (((int) color_use) >= MI_NPIXELS(mi))
+ color_use -= (float) MI_NPIXELS(mi);
+ while (((int) color_use) < 0)
+ color_use += (float) MI_NPIXELS(mi);
+ }
+#endif
+#ifdef COLORROUND
+ if (MI_NPIXELS(mi) > 2) {
+ color_use += SPINRATE * color_inc;
+ while (((int) color_use) >= MI_NPIXELS(mi))
+ color_use -= (float) MI_NPIXELS(mi);
+ }
+#endif
+ r1 = braid->min_radius + r_diff * (float) (s);
+ x_1 = r1 * COSF(t + psi) + braid->center_x;
+ y_1 = r1 * SINF(t + psi) + braid->center_y;
+ x_2 = r1 * COSF(t + t_inc + psi) + braid->center_x;
+ y_2 = r1 * SINF(t + t_inc + psi) + braid->center_y;
+ if (MI_NPIXELS(mi) > 2)
+ XSetForeground(display, MI_GC(mi), MI_PIXEL(mi, (int) color_use));
+ else
+ XSetForeground(display, MI_GC(mi), MI_WHITE_PIXEL(mi));
+
+ XDrawLine(display, window, MI_GC(mi),
+ (int) (x_1), (int) (y_1), (int) (x_2), (int) (y_2));
+ }
+ }
+ }
+ }
+ XSetLineAttributes(display, MI_GC(mi), 1, LineSolid, CapNotLast, JoinRound);
+
+ if (++braid->age > MI_CYCLES(mi)) {
+#ifdef STANDALONE
+ braid->eraser = erase_window (MI_DISPLAY(mi), MI_WINDOW(mi), braid->eraser);
+#endif
+ init_braid(mi);
+ }
+}
+
+ENTRYPOINT void
+release_braid(ModeInfo * mi)
+{
+ if (braids != NULL) {
+ (void) free((void *) braids);
+ braids = (braidtype *) NULL;
+ }
+}
+
+ENTRYPOINT void
+refresh_braid(ModeInfo * mi)
+{
+ MI_CLEARWINDOW(mi);
+}
+
+XSCREENSAVER_MODULE ("Braid", braid)
+
+#endif /* MODE_braid */
projects / xscreensaver / blobdiff