three.js platformer: fix pushing into box sides, desync coin spin

Ground support now uses the full aabb footprint so it matches the 2d
collision solver. Before, support was lost when the center crossed a
platform edge while the aabbs still overlapped, so the solid collision
gate flipped on in the already-overlapping state where the engine only
applies a gentle push-away that player input could overpower.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: KilledByAPixel

examples/threejs/platformer/game.js

@@ -63,9 +63,12 @@ class PlatformerObject extends LJS.ThreeJSObject
                 continue; // top is above our feet, sides handled by 2d collision
             if (platform.height < groundHeight)
                 continue; // already found something higher
-            // check if this object is inside the platform footprint
+            // check if this object's footprint overlaps the platform
+            // use the full aabb so support matches the 2d collision solver,
+            // otherwise the solid gate can flip on while already overlapping
             const delta = this.pos.subtract(platform.pos);
-            if (Math.abs(delta.x) < platform.size.x/2 && Math.abs(delta.y) < platform.size.y/2)
+            const sizeBoth = this.size.add(platform.size);
+            if (Math.abs(delta.x) < sizeBoth.x/2 && Math.abs(delta.y) < sizeBoth.y/2)
                 groundHeight = platform.height;
         }
         return groundHeight;
@@ -119,6 +122,7 @@ class Coin extends PlatformerObject
         super(pos, vec2(.6), group, zPos);
         this.angleVelocity = .03; // spin, the plugin syncs the mesh from angle
         this.angleDamping = 1;    // do not slow down
+        this.angle = pos.x + pos.y; // offset spin phase by position so coins are not in sync
     }
     update()
     {