changed determining "neighbors" from rectangular to circular perimeter

HISTORY.md

@@ -2,6 +2,8 @@
 
 ## in development:
 
+* **Notable Changes:**
+    * changed determining "neighbors" from rectangular to circular perimeter
 * **Notable Fixes:**
     * fixed stretching SVG costumes with fixed aspect ratios in Firefox
     * only report neighbors that are visible
@@ -13,6 +15,7 @@
 * threads: only report neighbors that are visible, thanks Frederic, for reporting this bug!
 * Italian translation update, thanks, Stefano!
 * Spanish translation update, thanks, Joan!
+* threads, objects: changed determining "neighbors" from rectangular to circular perimeter
 
 ### 2020-11-19
 * new dev version

snap.html

@@ -10,7 +10,7 @@
         <script src="src/widgets.js?version=2020-10-06"></script>
         <script src="src/blocks.js?version=2020-11-17"></script>
         <script src="src/threads.js?version=2020-11-20"></script>
-        <script src="src/objects.js?version=2020-11-19"></script>
+        <script src="src/objects.js?version=2020-11-20"></script>
         <script src="src/gui.js?version=2020-11-19"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
         <script src="src/lists.js?version=2020-07-01"></script>

src/objects.js

@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph,  BooleanSlotMorph,
 localize, TableMorph, TableFrameMorph, normalizeCanvas, VectorPaintEditorMorph,
 AlignmentMorph, Process, WorldMap, copyCanvas, useBlurredShadows*/
 
-modules.objects = '2020-November-19';
+modules.objects = '2020-November-20';
 
 var SpriteMorph;
 var StageMorph;
@@ -4387,6 +4387,47 @@ SpriteMorph.prototype.overlappingPixels = function (otherSprite) {
     ];
 };
 
+// SpriteMorph neighbor detection
+
+SpriteMorph.prototype.neighbors = function (aStage) {
+    var stage = aStage || this.parentThatIsA(StageMorph),
+        myPerimeter = this.perimeter(stage);
+    return new List(
+        stage.children.filter(each => {
+            var eachPerimeter,
+                distance;
+            if (each instanceof SpriteMorph &&
+                each.isVisible &&
+                (each !== this)
+            ) {
+                eachPerimeter = each.perimeter(stage);
+                distance = myPerimeter.center.distanceTo(eachPerimeter.center);
+                return (distance - myPerimeter.radius - eachPerimeter.radius)
+                    < 0;
+            }
+            return false;
+        })
+    );
+};
+
+SpriteMorph.prototype.perimeter = function (aStage) {
+    var stage = aStage || this.parentThatIsA(StageMorph),
+        stageScale = this instanceof StageMorph ? 1 : stage.scale,
+        radius;
+    if (this.costume) {
+        radius = Math.max(
+            this.costume.width(),
+            this.costume.height()
+        ) * this.scale * stageScale;
+    } else {
+        radius = Math.max(this.width(), this.height());
+    }
+    return {
+        center: this.center(), // geometric center rather than position
+        radius: radius * 1.5
+    };
+};
+
 // SpriteMorph pen ops
 
 SpriteMorph.prototype.doStamp = function () {
@@ -9044,16 +9085,16 @@ StageMorph.prototype.showingWatcher = SpriteMorph.prototype.showingWatcher;
 StageMorph.prototype.addVariable = SpriteMorph.prototype.addVariable;
 StageMorph.prototype.deleteVariable = SpriteMorph.prototype.deleteVariable;
 
+// StageMorph neighbor detection
+
+StageMorph.prototype.neighbors = SpriteMorph.prototype.neighbors;
+StageMorph.prototype.perimeter = SpriteMorph.prototype.perimeter;
+
 // StageMorph block rendering
 
-StageMorph.prototype.doScreenshot
-    = SpriteMorph.prototype.doScreenshot;
-
-StageMorph.prototype.newCostumeName
-    = SpriteMorph.prototype.newCostumeName;
-
-StageMorph.prototype.blockForSelector
-    = SpriteMorph.prototype.blockForSelector;
+StageMorph.prototype.doScreenshot = SpriteMorph.prototype.doScreenshot;
+StageMorph.prototype.newCostumeName = SpriteMorph.prototype.newCostumeName;
+StageMorph.prototype.blockForSelector = SpriteMorph.prototype.blockForSelector;
 
 // StageMorph variable watchers (for palette checkbox toggling)
 

src/threads.js

@@ -4856,7 +4856,6 @@ Process.prototype.reportGet = function (query) {
     // answer a reference to a first-class member
     // or a list of first-class members
     var thisObj = this.blockReceiver(),
-        neighborhood,
         stage,
         objName;
 
@@ -4896,6 +4895,9 @@ Process.prototype.reportGet = function (query) {
             return thisObj.isTemporary ?
                     this.reportGet(['clones']) : new List();
         case 'neighbors':
+            // old rectangular, bounding-box-based algorithm
+            // deprecated in favor of a circular perimeter based newer one
+            /*
             stage = thisObj.parentThatIsA(StageMorph);
             neighborhood = thisObj.bounds.expandBy(new Point(
                 thisObj.width(),
@@ -4909,6 +4911,8 @@ Process.prototype.reportGet = function (query) {
                         each.bounds.intersects(neighborhood)
                 )
             );
+            */
+            return thisObj.neighbors();
         case 'dangling?':
             return !thisObj.rotatesWithAnchor;
         case 'draggable?':