CURA-4320 Add circular prime tower setting and draw shadow according to

it.

cura/BuildVolume.py

@@ -737,12 +737,17 @@ class BuildVolume(SceneNode):
                 prime_tower_x = prime_tower_x - machine_width / 2 #Offset by half machine_width and _depth to put the origin in the front-left.
                 prime_tower_y = prime_tower_y + machine_depth / 2
 
-            prime_tower_area = Polygon([
-                [prime_tower_x - prime_tower_size, prime_tower_y - prime_tower_size],
-                [prime_tower_x, prime_tower_y - prime_tower_size],
-                [prime_tower_x, prime_tower_y],
-                [prime_tower_x - prime_tower_size, prime_tower_y],
-            ])
+            if self._global_container_stack.getProperty("prime_tower_circular", "value"):
+                radius = prime_tower_size / 2
+                prime_tower_area = Polygon.approximatedCircle(radius)
+                prime_tower_area = prime_tower_area.translate(prime_tower_x - radius, prime_tower_y - radius)
+            else:
+                prime_tower_area = Polygon([
+                    [prime_tower_x - prime_tower_size, prime_tower_y - prime_tower_size],
+                    [prime_tower_x, prime_tower_y - prime_tower_size],
+                    [prime_tower_x, prime_tower_y],
+                    [prime_tower_x - prime_tower_size, prime_tower_y],
+                ])
             prime_tower_area = prime_tower_area.getMinkowskiHull(Polygon.approximatedCircle(0))
             for extruder in used_extruders:
                 result[extruder.getId()].append(prime_tower_area) #The prime tower location is the same for each extruder, regardless of offset.

resources/definitions/fdmprinter.def.json

@@ -4747,6 +4747,17 @@
                     "settable_per_mesh": false,
                     "settable_per_extruder": false
                 },
+                "prime_tower_circular":
+                {
+                    "label": "Circular Prime Tower",
+                    "description": "Make the prime tower as a circular shape.",
+                    "type": "bool",
+                    "enabled": "resolveOrValue('prime_tower_enable')",
+                    "default_value": true,
+                    "resolve": "any(extruderValues('prime_tower_circular'))",
+                    "settable_per_mesh": false,
+                    "settable_per_extruder": false
+                },
                 "prime_tower_size":
                 {
                     "label": "Prime Tower Size",