--- /dev/null
+/* xscreensaver, Copyright (c) 1998-2002 Jamie Zawinski <jwz@jwz.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.
+ */
+
+#include "config.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include "rotator.h"
+#include "yarandom.h"
+
+struct rotator {
+
+ double spin_x_speed, spin_y_speed, spin_z_speed;
+ double wander_speed;
+
+ double rotx, roty, rotz; /* current object rotation */
+ double dx, dy, dz; /* current rotational velocity */
+ double ddx, ddy, ddz; /* current rotational acceleration */
+ double d_max; /* max rotational velocity */
+
+ int wander_frame; /* position in the wander cycle */
+
+};
+
+
+#undef ABS
+#define ABS(x) ((x)<0?-(x):(x))
+
+#define BELLRAND(n) ((frand((n)) + frand((n)) + frand((n))) / 3)
+#define RANDSIGN() ((random() & 1) ? 1 : -1)
+
+static void
+rotate_1 (double *pos, double *v, double *dv, double speed, double max_v)
+{
+ double ppos = *pos;
+
+ if (speed == 0) return;
+
+ /* tick position */
+ if (ppos < 0)
+ ppos = -(ppos + *v);
+ else
+ ppos += *v;
+
+ if (ppos > 1.0)
+ ppos -= 1.0;
+ else if (ppos < 0)
+ ppos += 1.0;
+
+ if (ppos < 0) abort();
+ if (ppos > 1.0) abort();
+ *pos = (*pos > 0 ? ppos : -ppos);
+
+ /* accelerate */
+ *v += *dv;
+
+ /* clamp velocity */
+ if (*v > max_v || *v < -max_v)
+ {
+ *dv = -*dv;
+ }
+ /* If it stops, start it going in the other direction. */
+ else if (*v < 0)
+ {
+ if (random() % 4)
+ {
+ *v = 0;
+
+ /* keep going in the same direction */
+ if (random() % 2)
+ *dv = 0;
+ else if (*dv < 0)
+ *dv = -*dv;
+ }
+ else
+ {
+ /* reverse gears */
+ *v = -*v;
+ *dv = -*dv;
+ *pos = -*pos;
+ }
+ }
+
+ /* Alter direction of rotational acceleration randomly. */
+ if (! (random() % 120))
+ *dv = -*dv;
+
+ /* Change acceleration very occasionally. */
+ if (! (random() % 200))
+ {
+ if (*dv == 0)
+ *dv = 0.00001;
+ else if (random() & 1)
+ *dv *= 1.2;
+ else
+ *dv *= 0.8;
+ }
+}
+
+
+/* Returns a rotator object, which encapsulates rotation and motion state.
+
+ spin_[xyz]_speed indicates the relative speed of rotation.
+ Specify 0 if you don't want any rotation around that axis.
+
+ spin_accel specifies a scaling factor for the acceleration that is
+ randomly applied to spin: if you want the speed to change faster,
+ make this > 1.
+
+ wander_speed indicates the relative speed through space.
+
+ If randomize_initial_state_p is true, then the initial position and
+ rotation will be randomized (even if the spin speeds are 0.) If it
+ is false, then all values will be initially zeroed.
+ */
+rotator *
+make_rotator (double spin_x_speed,
+ double spin_y_speed,
+ double spin_z_speed,
+ double spin_accel,
+ double wander_speed,
+ int randomize_initial_state_p)
+{
+ rotator *r = (rotator *) calloc (1, sizeof(*r));
+ double d, dd;
+
+ if (!r) return 0;
+
+ if (spin_x_speed < 0 || spin_y_speed < 0 || spin_z_speed < 0 ||
+ wander_speed < 0)
+ abort();
+
+ r->spin_x_speed = spin_x_speed;
+ r->spin_y_speed = spin_y_speed;
+ r->spin_z_speed = spin_z_speed;
+ r->wander_speed = wander_speed;
+
+ if (randomize_initial_state_p)
+ {
+ r->rotx = frand(1.0) * RANDSIGN();
+ r->roty = frand(1.0) * RANDSIGN();
+ r->rotz = frand(1.0) * RANDSIGN();
+
+ r->wander_frame = random() % 0xFFFF;
+ }
+ else
+ {
+ r->rotx = r->roty = r->rotz = 0;
+ r->wander_frame = 0;
+ }
+
+ d = 0.006;
+ dd = 0.00006;
+
+ r->dx = BELLRAND(d * r->spin_x_speed);
+ r->dy = BELLRAND(d * r->spin_y_speed);
+ r->dz = BELLRAND(d * r->spin_z_speed);
+
+ r->d_max = r->dx * 2;
+
+ r->ddx = (dd + frand(dd+dd)) * r->spin_x_speed * spin_accel;
+ r->ddy = (dd + frand(dd+dd)) * r->spin_y_speed * spin_accel;
+ r->ddz = (dd + frand(dd+dd)) * r->spin_z_speed * spin_accel;
+
+# if 0
+ fprintf (stderr, "rotator:\n");
+ fprintf (stderr, " wander: %3d %6.2f\n", r->wander_frame, r->wander_speed);
+ fprintf (stderr, " speed: %6.2f %6.2f %6.2f\n",
+ r->spin_x_speed, r->spin_y_speed, r->spin_z_speed);
+ fprintf (stderr, " rot: %6.2f %6.2f %6.2f\n",
+ r->rotx, r->roty, r->rotz);
+ fprintf (stderr, " d: %6.2f %6.2f %6.2f, %6.2f\n",
+ r->dx, r->dy, r->dz,
+ r->d_max);
+ fprintf (stderr, " dd: %6.2f %6.2f %6.2f\n",
+ r->ddx, r->ddy, r->ddz);
+# endif
+
+ return r;
+}
+
+
+void
+free_rotator (rotator *r)
+{
+ free (r);
+}
+
+void
+get_rotation (rotator *rot, double *x_ret, double *y_ret, double *z_ret,
+ int update_p)
+{
+ double x, y, z;
+
+ if (update_p) {
+ rotate_1 (&rot->rotx, &rot->dx, &rot->ddx, rot->spin_x_speed, rot->d_max);
+ rotate_1 (&rot->roty, &rot->dy, &rot->ddy, rot->spin_y_speed, rot->d_max);
+ rotate_1 (&rot->rotz, &rot->dz, &rot->ddz, rot->spin_z_speed, rot->d_max);
+ }
+
+ x = rot->rotx;
+ y = rot->roty;
+ z = rot->rotz;
+ if (x < 0) x = 1 - (x + 1);
+ if (y < 0) y = 1 - (y + 1);
+ if (z < 0) z = 1 - (z + 1);
+
+ if (x_ret) *x_ret = x;
+ if (y_ret) *y_ret = y;
+ if (z_ret) *z_ret = z;
+}
+
+
+void
+get_position (rotator *rot, double *x_ret, double *y_ret, double *z_ret,
+ int update_p)
+{
+ double x = 0.5, y = 0.5, z = 0.5;
+
+ if (rot->wander_speed != 0)
+ {
+ if (update_p)
+ rot->wander_frame++;
+
+# define SINOID(F) ((1 + sin((rot->wander_frame * (F)) / 2 * M_PI)) / 2.0)
+ x = SINOID (0.71 * rot->wander_speed);
+ y = SINOID (0.53 * rot->wander_speed);
+ z = SINOID (0.37 * rot->wander_speed);
+# undef SINOID
+ }
+
+ if (x_ret) *x_ret = x;
+ if (y_ret) *y_ret = y;
+ if (z_ret) *z_ret = z;
+}
projects / xscreensaver / blobdiff