Filled Polygon "nearby" sound effect

When red & green endpoint dots are being dragged near each other,
play a different sound.

Based on CC Attribution 4.0 sound by Eliot Lash
(see CHANGES.txt & AUTHORS.txt).

docs/AUTHORS.txt

@@ -153,13 +153,19 @@ June 17, 2002 - May 28, 2024
   Scanline polygon fill routine based on public-domain code
   by Darel Rex Finley, 2007 <https://alienryderflex.com/polygon_fill/>
 
-  Filled Polygon sound effects (place, move, finish) based on
+  Filled Polygon "place", "move", and "finish" sound effects based on
   "success_02.wav" (https://freesound.org/people/Kenneth_Cooney/sounds/463067/),
   "success.wav" (https://freesound.org/people/Kenneth_Cooney/sounds/457547/), &
   "Completed.wav" (https://freesound.org/people/Kenneth_Cooney/sounds/609336/)
   respectively.
   Creative Commons 0 by Kenneth Cooney <https://www.kennethcooney.com/>
 
+  Filled Polygon "nearby" sound effect based on "JacobsLadderSingle2.flac"
+  <https://freesound.org/people/Halleck/sounds/19487/>.
+  Creative Commons Attribution 4.0 by Eliot Lash
+  <https://freesound.org/people/Halleck/>
+  <https://www.eliotlash.com/>
+ 
   Bloom magic tool
   by Bill Kendrick <bill@newbreedsoftware.com>
   Googly Eyes sound effect: "Torch Crackle.wav"

docs/CHANGES.txt

@@ -21,10 +21,15 @@ https://tuxpaint.org/
       + Code & icon by Bill Kendrick <bill@newbreedsoftware.com>
       + Scanline polygon fill routine based on public-domain code
         by Darel Rex Finley, 2007 <https://alienryderflex.com/polygon_fill/
-      + Sound effects based on "success.wav", "success_02.wav", and
+      + Sound effects based on
-        "Completed.wav", Creative Commons 0 by Kenneth Cooney
+        - "success.wav", "success_02.wav", and "Completed.wav",
+          Creative Commons 0 by Kenneth Cooney
           <https://freesound.org/people/Kenneth_Cooney>
           <https://www.kennethcooney.com/>
+        - "JacobsLadderSingle2.flac",
+          Creative Commons Attribution 4.0 by Eliot Lash
+          <https://freesound.org/people/Halleck/>
+          <https://www.eliotlash.com/>
       Closes https://sourceforge.net/p/tuxpaint/feature-requests/251/
 
   * Magic Tool Improvements:

magic/src/polyfill.c

@@ -41,6 +41,7 @@ char *polyfill_icon_filenames[NUM_TOOLS] = {
 enum {
   SND_PLACE,
   SND_MOVE,
+  SND_NEARBY,
   SND_FINISH,
   NUM_SOUNDS
 };
@@ -48,6 +49,7 @@ enum {
 char *polyfill_snd_filenames[NUM_SOUNDS] = {
   "polyfill_place.ogg",
   "polyfill_move.ogg",
+  "polyfill_nearby.ogg",
   "polyfill_finish.ogg",
 };
 
@@ -281,7 +283,29 @@ polyfill_drag(magic_api * api, int which ATTRIBUTE_UNUSED,
   polyfill_pt_y[polyfill_editing] = y;
 
   polyfill_draw_preview(api, canvas, 1);
+
+  if (polyfill_editing == polyfill_num_pts - 1 &&
+      polyfill_num_pts >= 3 &&
+      x >= polyfill_pt_x[0] - SNAP_SIZE &&
+      x <= polyfill_pt_x[0] + SNAP_SIZE &&
+      y >= polyfill_pt_y[0] - SNAP_SIZE &&
+      y <= polyfill_pt_y[0] + SNAP_SIZE) {
+    /* If placing/moving the final (red) point, and it's
+       near the initial (green) point, play an electrostatic sound */
+    api->playsound(snd_effects[SND_NEARBY], (x * 255) / canvas->w, 255);
+  } else if (polyfill_editing == 0 && 
+      polyfill_num_pts >= 3 &&
+      x >= polyfill_pt_x[polyfill_num_pts - 1] - SNAP_SIZE &&
+      x <= polyfill_pt_x[polyfill_num_pts - 1] + SNAP_SIZE &&
+      y >= polyfill_pt_y[polyfill_num_pts - 1] - SNAP_SIZE &&
+      y <= polyfill_pt_y[polyfill_num_pts - 1] + SNAP_SIZE) {
+    /* If moving the initial (green) point, and it's
+       near the final (red) point, also play an electrostatic sound */
+    api->playsound(snd_effects[SND_NEARBY], (x * 255) / canvas->w, 255);
+  } else {
+    /* Otherwise, play the normal "moving a point" sound */
     api->playsound(snd_effects[SND_MOVE], (x * 255) / canvas->w, 255);
+  }
 
   update_rect->x = 0;
   update_rect->y = 0;