--- /dev/null
+/* -*- Mode: C; tab-width: 4 -*-
+ * lightning --- fractal lightning bolts.
+ */
+#if !defined( lint ) && !defined( SABER )
+static const char sccsid[] = "@(#)lightning.c 4.00 97/01/01 xlockmore";
+#endif
+
+/* Copyright (c) 1996 by Keith Romberg <kromberg@saxe.com>.
+ *
+ * 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:
+ * 10-May-97: jwz@netscape.com: turned into a standalone program.
+ * 14-Jul-96: Cleaned up code.
+ * 27-Jun-96: Written and submitted by Keith Romberg <kromberg@saxe.com>.
+ */
+
+#ifdef STANDALONE
+# define PROGCLASS "Lightning"
+# define HACK_INIT init_lightning
+# define HACK_DRAW draw_lightning
+# define lightning_opts xlockmore_opts
+# define DEFAULTS "*delay: 10000 \n" \
+ "*ncolors: 200 \n"
+# define BRIGHT_COLORS
+# include "xlockmore.h" /* from the xscreensaver distribution */
+#else /* !STANDALONE */
+# include "xlock.h" /* from the xlockmore distribution */
+#endif /* !STANDALONE */
+
+ModeSpecOpt lightning_opts = {
+ 0, NULL, 0, NULL, NULL };
+
+/*---------------------------- defines -------------------------------*/
+
+#define BOLT_NUMBER 4
+#define BOLT_ITERATION 4
+#define LONG_FORK_ITERATION 3
+#define MEDIUM_FORK_ITERATION 2
+#define SMALL_FORK_ITERATION 1
+
+#define WIDTH_VARIATION 30
+#define HEIGHT_VARIATION 15
+
+#define DELAY_TIME_AMOUNT 15
+#define MULTI_DELAY_TIME_BASE 5
+
+#define MAX_WIGGLES 16
+#define WIGGLE_BASE 8
+#define WIGGLE_AMOUNT 14
+
+#define RANDOM_FORK_PROBILITY 4
+
+#define FIRST_LEVEL_STRIKE 0
+#define LEVEL_ONE_STRIKE 1
+#define LEVEL_TWO_STRIKE 2
+
+#define BOLT_VERTICIES ((1<<BOLT_ITERATION)-1)
+ /* BOLT_ITERATION = 4. 2^(BOLT_ITERATION) - 1 = 15 */
+
+#define NUMBER_FORK_VERTICIES 9
+
+#define FLASH_PROBILITY 20
+#define MAX_FLASH_AMOUNT 2 /* half the total duration of the bolt */
+
+typedef struct {
+ XPoint ForkVerticies[NUMBER_FORK_VERTICIES];
+ int num_used;
+} Fork;
+
+typedef struct {
+ XPoint end1, end2;
+ XPoint middle[BOLT_VERTICIES];
+ int fork_number;
+ int forks_start[2];
+ Fork branch[2];
+ int wiggle_number;
+ int wiggle_amount;
+ int delay_time;
+ int flash;
+ int flash_begin, flash_stop;
+ int visible;
+ int strike_level;
+} Lightning;
+
+typedef struct {
+ Lightning bolts[BOLT_NUMBER];
+ int scr_width, scr_height;
+ int multi_strike;
+ int give_it_hell;
+ int draw_time;
+ int stage;
+ unsigned long color;
+} Storm;
+
+static Storm *Helga = NULL;
+
+/*------------------- function prototypes ----------------------------*/
+
+static int distance(XPoint a, XPoint b);
+
+static int setup_multi_strike(void);
+static int flashing_strike(void);
+static void flash_duration(int *start, int *end, int total_duration);
+static void random_storm(Storm * st);
+static void generate(XPoint A, XPoint B, int iter, XPoint * verts, int *index);
+static void create_fork(Fork * f, XPoint start, XPoint end, int level);
+
+static void first_strike(Lightning bolt, ModeInfo * mi);
+static void draw_bolt(Lightning * bolt, ModeInfo * mi);
+static void draw_line(ModeInfo * mi, XPoint * p, int number, GC use, int x_offset);
+static void level1_strike(Lightning bolt, ModeInfo * mi);
+static void level2_strike(Lightning bolt, ModeInfo * mi);
+
+static int storm_active(Storm * st);
+static void update_bolt(Lightning * bolt, int time);
+static void wiggle_bolt(Lightning * bolt);
+static void wiggle_line(XPoint * p, int number, int wiggle_amount);
+
+/*------------------------- functions ---------------------------------*/
+
+static int
+setup_multi_strike(void)
+{
+ int result, multi_prob;
+
+ multi_prob = NRAND(100);
+
+ if (multi_prob < 50)
+ result = 1;
+ else if ((multi_prob >= 51) && (multi_prob < 75))
+ result = 2;
+ else if ((multi_prob >= 76) && (multi_prob < 92))
+ result = 3;
+ else
+ result = BOLT_NUMBER; /* 4 */
+
+ return (result);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int
+flashing_strike(void)
+{
+ int tmp = NRAND(FLASH_PROBILITY);
+
+ if (tmp <= FLASH_PROBILITY)
+ return (1);
+ return (0);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void
+flash_duration(int *start, int *end, int total_duration)
+{
+ int mid, d;
+
+ mid = total_duration / MAX_FLASH_AMOUNT;
+ d = NRAND(total_duration / MAX_FLASH_AMOUNT) / 2;
+ *start = mid - d;
+ *end = mid + d;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void
+random_storm(Storm * st)
+{
+ int i, j, tmp;
+ XPoint p;
+
+ for (i = 0; i < st->multi_strike; i++) {
+ st->bolts[i].end1.x = NRAND(st->scr_width);
+ st->bolts[i].end1.y = 0;
+ st->bolts[i].end2.x = NRAND(st->scr_width);
+ st->bolts[i].end2.y = st->scr_height;
+ st->bolts[i].wiggle_number = WIGGLE_BASE + NRAND(MAX_WIGGLES);
+ if ((st->bolts[i].flash = flashing_strike()))
+ flash_duration(&(st->bolts[i].flash_begin), &(st->bolts[i].flash_stop),
+ st->bolts[i].wiggle_number);
+ else
+ st->bolts[i].flash_begin = st->bolts[i].flash_stop = 0;
+ st->bolts[i].wiggle_amount = WIGGLE_AMOUNT;
+ if (i == 0)
+ st->bolts[i].delay_time = NRAND(DELAY_TIME_AMOUNT);
+ else
+ st->bolts[i].delay_time = NRAND(DELAY_TIME_AMOUNT) +
+ (MULTI_DELAY_TIME_BASE * i);
+ st->bolts[i].strike_level = FIRST_LEVEL_STRIKE;
+ tmp = 0;
+ generate(st->bolts[i].end1, st->bolts[i].end2, BOLT_ITERATION,
+ st->bolts[i].middle, &tmp);
+ st->bolts[i].fork_number = 0;
+ st->bolts[i].visible = 0;
+ for (j = 0; j < BOLT_VERTICIES; j++) {
+ if (st->bolts[i].fork_number >= 2)
+ break;
+ if (NRAND(100) < RANDOM_FORK_PROBILITY) {
+ p.x = NRAND(st->scr_width);
+ p.y = st->scr_height;
+ st->bolts[i].forks_start[st->bolts[i].fork_number] = j;
+ create_fork(&(st->bolts[i].branch[st->bolts[i].fork_number]),
+ st->bolts[i].middle[j], p, j);
+ st->bolts[i].fork_number++;
+ }
+ }
+ }
+}
+
+static void
+generate(XPoint A, XPoint B, int iter, XPoint * verts, int *index)
+{
+ XPoint mid;
+
+ mid.x = (A.x + B.x) / 2 + NRAND(WIDTH_VARIATION) - WIDTH_VARIATION / 2;
+ mid.y = (A.y + B.y) / 2 + NRAND(HEIGHT_VARIATION) - HEIGHT_VARIATION / 2;
+
+ if (!iter) {
+ verts[*index].x = mid.x;
+ verts[*index].y = mid.y;
+ (*index)++;
+ return;
+ }
+ generate(A, mid, iter - 1, verts, index);
+ generate(mid, B, iter - 1, verts, index);
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+create_fork(Fork * f, XPoint start, XPoint end, int level)
+{
+ int tmp = 1;
+
+ f->ForkVerticies[0].x = start.x;
+ f->ForkVerticies[0].y = start.y;
+
+ if (level <= 6) {
+ generate(start, end, LONG_FORK_ITERATION, f->ForkVerticies, &tmp);
+ f->num_used = 9;
+ } else if ((level > 6) && (level <= 11)) {
+ generate(start, end, MEDIUM_FORK_ITERATION, f->ForkVerticies, &tmp);
+ f->num_used = 5;
+ } else {
+ if (distance(start, end) > 100) {
+ generate(start, end, MEDIUM_FORK_ITERATION, f->ForkVerticies, &tmp);
+ f->num_used = 5;
+ } else {
+ generate(start, end, SMALL_FORK_ITERATION, f->ForkVerticies, &tmp);
+ f->num_used = 3;
+ }
+ }
+
+ f->ForkVerticies[f->num_used - 1].x = end.x;
+ f->ForkVerticies[f->num_used - 1].y = end.y;
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+update_bolt(Lightning * bolt, int time)
+{
+ wiggle_bolt(bolt);
+ if ((bolt->wiggle_amount == 0) && (bolt->wiggle_number > 2))
+ bolt->wiggle_number = 0;
+ if (((time % 3) == 0))
+ bolt->wiggle_amount++;
+
+ if (((time >= bolt->delay_time) && (time < bolt->flash_begin)) ||
+ (time > bolt->flash_stop))
+ bolt->visible = 1;
+ else
+ bolt->visible = 0;
+
+ if (time == bolt->delay_time)
+ bolt->strike_level = FIRST_LEVEL_STRIKE;
+ else if (time == (bolt->delay_time + 1))
+ bolt->strike_level = LEVEL_ONE_STRIKE;
+ else if ((time > (bolt->delay_time + 1)) &&
+ (time <= (bolt->delay_time + bolt->flash_begin - 2)))
+ bolt->strike_level = LEVEL_TWO_STRIKE;
+ else if (time == (bolt->delay_time + bolt->flash_begin - 1))
+ bolt->strike_level = LEVEL_ONE_STRIKE;
+ else if (time == (bolt->delay_time + bolt->flash_stop + 1))
+ bolt->strike_level = LEVEL_ONE_STRIKE;
+ else
+ bolt->strike_level = LEVEL_TWO_STRIKE;
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+draw_bolt(Lightning * bolt, ModeInfo * mi)
+{
+ if (bolt->visible) {
+ if (bolt->strike_level == FIRST_LEVEL_STRIKE)
+ first_strike(*bolt, mi);
+ else if (bolt->strike_level == LEVEL_ONE_STRIKE)
+ level1_strike(*bolt, mi);
+ else
+ level2_strike(*bolt, mi);
+ }
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+first_strike(Lightning bolt, ModeInfo * mi)
+{
+ Display *display = MI_DISPLAY(mi);
+ Window window = MI_WINDOW(mi);
+ GC gc = MI_GC(mi);
+ int i;
+
+ XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
+ XDrawLine(display, window, gc,
+ bolt.end1.x, bolt.end1.y, bolt.middle[0].x, bolt.middle[0].y);
+ draw_line(mi, bolt.middle, BOLT_VERTICIES, gc, 0);
+ XDrawLine(display, window, gc,
+ bolt.middle[BOLT_VERTICIES - 1].x, bolt.middle[BOLT_VERTICIES - 1].y,
+ bolt.end2.x, bolt.end2.y);
+
+ for (i = 0; i < bolt.fork_number; i++)
+ draw_line(mi, bolt.branch[i].ForkVerticies, bolt.branch[i].num_used,
+ gc, 0);
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+draw_line(ModeInfo * mi, XPoint * points, int number, GC to_use, int offset)
+{
+ int i;
+
+ for (i = 0; i < number - 1; i++) {
+ if (points[i].y <= points[i + 1].y)
+ XDrawLine(MI_DISPLAY(mi), MI_WINDOW(mi), to_use, points[i].x + offset,
+ points[i].y, points[i + 1].x + offset, points[i + 1].y);
+ else {
+ if (points[i].x < points[i + 1].x)
+ XDrawLine(MI_DISPLAY(mi), MI_WINDOW(mi), to_use, points[i].x +
+ offset, points[i].y + offset, points[i + 1].x + offset,
+ points[i + 1].y + offset);
+ else
+ XDrawLine(MI_DISPLAY(mi), MI_WINDOW(mi), to_use, points[i].x -
+ offset, points[i].y + offset, points[i + 1].x - offset,
+ points[i + 1].y + offset);
+ }
+ }
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+level1_strike(Lightning bolt, ModeInfo * mi)
+{
+ Display *display = MI_DISPLAY(mi);
+ Window window = MI_WINDOW(mi);
+ Storm *st = &Helga[MI_SCREEN(mi)];
+ GC gc = MI_GC(mi);
+ int i;
+
+ if (MI_NPIXELS(mi) > 2) /* color */
+ XSetForeground(display, gc, MI_PIXEL(mi, st->color));
+ else
+ XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
+ XDrawLine(display, window, gc,
+ bolt.end1.x - 1, bolt.end1.y, bolt.middle[0].x - 1, bolt.middle[0].y);
+ draw_line(mi, bolt.middle, BOLT_VERTICIES, gc, -1);
+ XDrawLine(display, window, gc,
+ bolt.middle[BOLT_VERTICIES - 1].x - 1,
+ bolt.middle[BOLT_VERTICIES - 1].y, bolt.end2.x - 1, bolt.end2.y);
+ XDrawLine(display, window, gc,
+ bolt.end1.x + 1, bolt.end1.y, bolt.middle[0].x + 1, bolt.middle[0].y);
+ draw_line(mi, bolt.middle, BOLT_VERTICIES, gc, 1);
+ XDrawLine(display, window, gc,
+ bolt.middle[BOLT_VERTICIES - 1].x + 1,
+ bolt.middle[BOLT_VERTICIES - 1].y, bolt.end2.x + 1, bolt.end2.y);
+
+ for (i = 0; i < bolt.fork_number; i++) {
+ draw_line(mi, bolt.branch[i].ForkVerticies, bolt.branch[i].num_used,
+ gc, -1);
+ draw_line(mi, bolt.branch[i].ForkVerticies, bolt.branch[i].num_used,
+ gc, 1);
+ }
+ first_strike(bolt, mi);
+}
+
+/*------------------------------------------------------------------------*/
+
+static int
+distance(XPoint a, XPoint b)
+{
+ return ((int) sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y)));
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+level2_strike(Lightning bolt, ModeInfo * mi)
+{
+ Display *display = MI_DISPLAY(mi);
+ Window window = MI_WINDOW(mi);
+ Storm *st = &Helga[MI_SCREEN(mi)];
+ GC gc = MI_GC(mi);
+ int i;
+
+ /* This was originally designed to be a little darker then the
+ level1 strike. This was changed to get it to work on
+ multiscreens and to add more color variety. I tried
+ stippling but it did not look good. */
+ if (MI_NPIXELS(mi) > 2)
+ XSetForeground(display, gc, MI_PIXEL(mi, st->color));
+ else
+ XSetForeground(display, gc, MI_WIN_WHITE_PIXEL(mi));
+ XDrawLine(display, window, gc,
+ bolt.end1.x - 2, bolt.end1.y, bolt.middle[0].x - 2, bolt.middle[0].y);
+ draw_line(mi, bolt.middle, BOLT_VERTICIES, gc, -2);
+ XDrawLine(display, window, gc,
+ bolt.middle[BOLT_VERTICIES - 1].x - 2,
+ bolt.middle[BOLT_VERTICIES - 1].y, bolt.end2.x - 2, bolt.end2.y);
+
+ XDrawLine(display, window, gc,
+ bolt.end1.x + 2, bolt.end1.y, bolt.middle[0].x + 2, bolt.middle[0].y);
+ draw_line(mi, bolt.middle, BOLT_VERTICIES, gc, 2);
+ XDrawLine(display, window, gc,
+ bolt.middle[BOLT_VERTICIES - 1].x + 2,
+ bolt.middle[BOLT_VERTICIES - 1].y, bolt.end2.x + 2, bolt.end2.y);
+
+ for (i = 0; i < bolt.fork_number; i++) {
+ draw_line(mi, bolt.branch[i].ForkVerticies, bolt.branch[i].num_used,
+ gc, -2);
+ draw_line(mi, bolt.branch[i].ForkVerticies, bolt.branch[i].num_used,
+ gc, 2);
+ }
+ level1_strike(bolt, mi);
+}
+
+/*------------------------------------------------------------------------*/
+
+static int
+storm_active(Storm * st)
+{
+ int i, atleast_1 = 0;
+
+ for (i = 0; i < st->multi_strike; i++)
+ if (st->bolts[i].wiggle_number > 0)
+ atleast_1++;
+
+ return (atleast_1);
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+wiggle_bolt(Lightning * bolt)
+{
+ int i;
+
+ wiggle_line(bolt->middle, BOLT_VERTICIES, bolt->wiggle_amount);
+ bolt->end2.x += NRAND(bolt->wiggle_amount) - bolt->wiggle_amount / 2;
+ bolt->end2.y += NRAND(bolt->wiggle_amount) - bolt->wiggle_amount / 2;
+
+ for (i = 0; i < bolt->fork_number; i++) {
+ wiggle_line(bolt->branch[i].ForkVerticies, bolt->branch[i].num_used,
+ bolt->wiggle_amount);
+ bolt->branch[i].ForkVerticies[0].x = bolt->middle[bolt->forks_start[i]].x;
+ bolt->branch[i].ForkVerticies[0].y = bolt->middle[bolt->forks_start[i]].y;
+ }
+
+ if (bolt->wiggle_amount > 1)
+ bolt->wiggle_amount -= 1;
+ else
+ bolt->wiggle_amount = 0;
+}
+
+/*------------------------------------------------------------------------*/
+
+static void
+wiggle_line(XPoint * p, int number, int amount)
+{
+ int i;
+
+ for (i = 0; i < number; i++) {
+ p[i].x += NRAND(amount) - amount / 2;
+ p[i].y += NRAND(amount) - amount / 2;
+ }
+}
+
+/*------------------------------------------------------------------------*/
+
+void
+init_lightning(ModeInfo * mi)
+{
+ Storm *st;
+
+ if (Helga == NULL) {
+ if ((Helga = (Storm *) calloc(MI_NUM_SCREENS(mi),
+ sizeof (Storm))) == NULL)
+ return;
+ }
+ st = &Helga[MI_SCREEN(mi)];
+
+ st->scr_width = MI_WIN_WIDTH(mi);
+ st->scr_height = MI_WIN_HEIGHT(mi);
+
+ st->multi_strike = setup_multi_strike();
+ random_storm(st);
+ st->stage = 0;
+}
+
+/*------------------------------------------------------------------------*/
+
+void
+draw_lightning(ModeInfo * mi)
+{
+ Storm *st = &Helga[MI_SCREEN(mi)];
+ int i;
+
+ switch (st->stage) {
+ case 0:
+ XClearWindow(MI_DISPLAY(mi), MI_WINDOW(mi));
+ st->color = NRAND(MI_NPIXELS(mi));
+ st->draw_time = 0;
+ if (storm_active(st))
+ st->stage++;
+ else
+ st->stage = 3;
+ break;
+ case 1:
+ for (i = 0; i < st->multi_strike; i++) {
+ if (st->bolts[i].visible)
+ draw_bolt(&(st->bolts[i]), mi);
+ update_bolt(&(st->bolts[i]), st->draw_time);
+ }
+ st->draw_time++;
+ XFlush(MI_DISPLAY(mi));
+ MI_PAUSE(mi) = 60000;
+ st->stage++;
+ break;
+ case 2:
+ XClearWindow(MI_DISPLAY(mi), MI_WINDOW(mi));
+ if (storm_active(st))
+ st->stage = 1;
+ else
+ st->stage++;
+ break;
+ case 3:
+ MI_PAUSE(mi) = 1000000;
+ init_lightning(mi);
+ break;
+ }
+}
+
+void
+release_lightning(ModeInfo * mi)
+{
+ if (Helga != NULL) {
+ (void) free((void *) Helga);
+ Helga = NULL;
+ }
+}
+
+void
+refresh_lightning(ModeInfo * mi)
+{
+ /* Do nothing, it will refresh by itself */
+}
projects / xscreensaver / blobdiff