http://www.ibiblio.org/pub/historic-linux/ftp-archives/sunsite.unc.edu/Sep-29-1996...

[xscreensaver] / hacks / attraction.c

diff --git a/hacks/attraction.c b/hacks/attraction.c
index 7844154a8f32c7dbd0c9836e74b546fb4e04a15d..8e3f188f3584f8ac9b9e982c2c8d715a97a67f05 100644 (file)
--- a/hacks/attraction.c
+++ b/hacks/attraction.c
@@ -1,4 +1,4 @@
-/* xscreensaver, Copyright (c) 1992 Jamie Zawinski <jwz@mcom.com>
+/* xscreensaver, Copyright (c) 1992, 1995 Jamie Zawinski <jwz@netscape.com>
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
@@ -11,7 +11,8 @@
 
 /* Simulation of a pair of quasi-gravitational fields, maybe sorta kinda
    a little like the strong and weak electromagnetic forces.  Derived from
-   a Lispm screensaver by John Pezaris <pz@mit.edu>.
+   a Lispm screensaver by John Pezaris <pz@mit.edu>.  Mouse control and
+   viscosity added by "Philip Edward Cutone, III" <pc2d+@andrew.cmu.edu>.
 
    John sez:
 
@@ -32,15 +33,20 @@
    The 1/r^2, -1/r^2, -10/r^2 thresholds proved not only robust but also
    interesting -- the orbs never collided and the threshold viscosity fixed
    the non-conservational problem.
+
+   Philip sez:
+   > An even normal viscosity (rather than the thresholded version to
+   > bleed excess energy) is also not interesting.
+
+   unless you make about 200 points.... set the viscosity to about .8
+   and drag the mouse through it.   it makes a nice wave which travels
+   through the field.
  */
 
-#include "screenhack.h"
-#include "spline.h"
 #include <stdio.h>
 #include <math.h>
-#if __STDC__
-#include <math.h>      /* for M_PI */
-#endif
+#include "screenhack.h"
+#include "spline.h"
 
 struct ball {
   float x, y;
@@ -66,6 +72,11 @@ static int point_stack_size, point_stack_fp, pixel_stack_fp, pixel_stack_size;
 static unsigned long *pixel_stack;
 static unsigned int color_shift;
 
+/*flip mods for mouse interaction*/
+static Bool mouse_p;
+int mouse_x, mouse_y, mouse_mass, root_x, root_y;
+static float viscosity;
+
 static enum object_mode {
   ball_mode, line_mode, polygon_mode, spline_mode, spline_filled_mode,
   tail_mode
@@ -122,6 +133,13 @@ init_balls (dpy, window)
   color_shift = get_integer_resource ("colorShift", "Integer");
   if (color_shift >= 360) color_shift = 5;
 
+  /*flip mods for mouse interaction*/
+  mouse_p = get_boolean_resource ("mouse", "Boolean");
+  mouse_mass = get_integer_resource ("mouseSize", "Integer");
+  mouse_mass =  mouse_mass *  mouse_mass *10;
+
+  viscosity = get_float_resource ("viscosity", "Float");
+
   mode_str = get_string_resource ("mode", "Mode");
   if (! mode_str) mode = ball_mode;
   else if (!strcmp (mode_str, "balls")) mode = ball_mode;
@@ -272,6 +290,7 @@ compute_force (i, dx_ret, dy_ret)
      float *dx_ret, *dy_ret;
 {
   int j;
+  float x_dist, y_dist, dist, dist2;
   *dx_ret = 0;
   *dy_ret = 0;
   for (j = 0; j < npoints; j++)
@@ -298,6 +317,28 @@ compute_force (i, dx_ret, dy_ret)
          *dy_ret += (frand (10.0) - 5.0);
        }
     }
+
+  if (mouse_p)
+    {
+      x_dist = mouse_x - balls [i].x;
+      y_dist = mouse_y - balls [i].y;
+      dist2 = (x_dist * x_dist) + (y_dist * y_dist);
+      dist = sqrt (dist2);
+       
+      if (dist > 0.1) /* the balls are not overlapping */
+       {
+         float new_acc = ((mouse_mass / dist2) *
+                          ((dist < threshold) ? -1.0 : 1.0));
+         float new_acc_dist = new_acc / dist;
+         *dx_ret += new_acc_dist * x_dist;
+         *dy_ret += new_acc_dist * y_dist;
+       }
+      else
+       {               /* the balls are overlapping; move randomly */
+         *dx_ret += (frand (10.0) - 5.0);
+         *dy_ret += (frand (10.0) - 5.0);
+       }
+    }
 }
 
 static void
@@ -310,6 +351,15 @@ run_balls (dpy, window)
   static Colormap cmap;
   int i;
 
+  /*flip mods for mouse interaction*/
+  Window  root1, child1;
+  int mask;
+  if (mouse_p)
+    {
+      XQueryPointer(dpy, window, &root1, &child1,
+                   &root_x, &root_y, &mouse_x, &mouse_y, &mask);
+    }
+
   if (tick++ == 500)
     {
       XWindowAttributes xgwa;
@@ -341,11 +391,20 @@ run_balls (dpy, window)
          balls[i].vx *= 0.9;
          balls[i].dx = 0;
        }
+      else if (viscosity != 1)
+       {
+         balls[i].vx *= viscosity;
+       }
+
       if (balls[i].vy > 10)
        {
          balls[i].vy *= 0.9;
          balls[i].dy = 0;
        }
+      else if (viscosity != 1)
+       {
+         balls[i].vy *= viscosity;
+       }
 
       balls[i].x += balls[i].vx;
       balls[i].y += balls[i].vy;
@@ -435,7 +494,7 @@ run_balls (dpy, window)
        abort ();
       if (!mono_p)
        {
-         XColor color2;
+         XColor color2, desired;
          color2 = balls [0].color;
          switch (cmode)
            {
@@ -451,7 +510,18 @@ run_balls (dpy, window)
              abort ();
            }
              
-         if (!XAllocColor (dpy, cmap, &color2))
+         desired = color2;
+         if (XAllocColor (dpy, cmap, &color2))
+           {
+             /* XAllocColor returns the actual RGB that the hardware let us
+                allocate.  Restore the requested values into the XColor struct
+                so that limited-resolution hardware doesn't cause cycle_hue to
+                get "stuck". */
+             color2.red = desired.red;
+             color2.green = desired.green;
+             color2.blue = desired.blue;
+           }
+         else
            {
              color2 = balls [0].color;
              if (!XAllocColor (dpy, cmap, &balls [0].color))
@@ -569,6 +639,9 @@ char *defaults [] = {
   "*threshold: 100",
   "*delay:     10000",
   "*glow:      false",
+  "*mouseSize: 10",
+  "*mouse:     false",
+  "*viscosity: 1",
   "*orbit:     false",
   "*colorShift:        3",
   "*segments:  100",
@@ -588,6 +661,10 @@ XrmOptionDescRec options [] = {
   { "-vx",             ".vx",          XrmoptionSepArg, 0 },
   { "-vy",             ".vy",          XrmoptionSepArg, 0 },
   { "-vmult",          ".vMult",       XrmoptionSepArg, 0 },
+  { "-mouse-size",     ".mouseSize",   XrmoptionSepArg, 0 },
+  { "-mouse",          ".mouse",       XrmoptionNoArg, "true" },
+  { "-nomouse",                ".mouse",       XrmoptionNoArg, "false" },
+  { "-viscosity",      ".viscosity",   XrmoptionSepArg, 0 },
   { "-glow",           ".glow",        XrmoptionNoArg, "true" },
   { "-noglow",         ".glow",        XrmoptionNoArg, "false" },
   { "-orbit",          ".orbit",       XrmoptionNoArg, "true" }