disapearing polygons.....now fixed :D

polygon lib calculate triangle area sometimes returned invalid value -> caused by sqrt of negative number

Author: SoloByte

demo/src/RigidBody2D.tscn

@@ -22,7 +22,7 @@ show_behind_parent = true
 color = Color( 0.545098, 0.545098, 0.545098, 1 )
 
 [node name="Line2D" type="Line2D" parent="Polygon2D"]
-default_color = Color( 1.5, 1.5, 1.5, 1 )
+default_color = Color( 1.35, 1.35, 1.35, 1 )
 joint_mode = 2
 begin_cap_mode = 2
 end_cap_mode = 2

polygon2d-fracture/PolygonFracture.gd

@@ -66,10 +66,8 @@ func fractureSimple(source_polygon : PoolVector2Array, world_pos : Vector2, worl
 		var triangulation : Dictionary = PolygonLib.triangulatePolygon(poly, true, true)
 
 		if triangulation.area > min_discard_area:
-			var shape_info : Dictionary = PolygonLib.getShapeInfo(Transform2D(world_rot_rad, world_pos), poly, false)
-			shape_info.area = triangulation.area
+			var shape_info : Dictionary = PolygonLib.getShapeInfoSimple(Transform2D(world_rot_rad, world_pos), poly, triangulation)
 			fracture_info.append(shape_info)
-#			fracture_info.append(PolygonLib.makeShapeInfo(poly, PolygonLib.getPolygonCentroid(triangulation.triangles, triangulation.area), world_pos, triangulation.area))
 
 	return fracture_info
 
@@ -100,10 +98,8 @@ func fracture(source_polygon : PoolVector2Array, world_pos : Vector2, world_rot_
 		var triangulation : Dictionary = PolygonLib.triangulatePolygon(poly, true, true)
 
 		if triangulation.area > min_discard_area:
-			var shape_info : Dictionary = PolygonLib.getShapeInfo(Transform2D(world_rot_rad, world_pos), poly, false)
-			shape_info.area = triangulation.area
+			var shape_info : Dictionary = PolygonLib.getShapeInfoSimple(Transform2D(world_rot_rad, world_pos), poly, triangulation)
 			fracture_info.append(shape_info)
-#			fracture_info.append(PolygonLib.makeShapeInfo(poly, PolygonLib.getPolygonCentroid(triangulation.triangles, triangulation.area), world_pos, triangulation.area))
 
 	return fracture_info
 
@@ -129,14 +125,11 @@ func fractureDelaunay(source_polygon : PoolVector2Array, world_pos : Vector2, wo
 					if area >= min_discard_area:
 						var centroid : Vector2 = PolygonLib.getTriangleCentroid(r)
 						fracture_info.append(PolygonLib.makeShapeInfo(PolygonLib.translatePolygon(r, -centroid), centroid, world_pos, triangle.area))
-#						fracture_info.append(PolygonLib.makeShapeInfo(r, PolygonLib.getTriangleCentroid(r), world_pos, area))
 				else:
 					var t : Dictionary = PolygonLib.triangulatePolygon(r, true, true)
 					if t.area >= min_discard_area:
-						var shape_info : Dictionary = PolygonLib.getShapeInfo(Transform2D(world_rot_rad, world_pos), triangle.points, false)
-						shape_info.area = triangle.area
+						var shape_info : Dictionary = PolygonLib.getShapeInfoSimple(Transform2D(world_rot_rad, world_pos), triangle.points, t)
 						fracture_info.append(shape_info)
-#						fracture_info.append(PolygonLib.makeShapeInfo(r, PolygonLib.getPolygonCentroid(t.triangles, t.area), world_pos, t.area))
 
 	return fracture_info
 
@@ -199,14 +192,14 @@ func cutFracture(source_polygon : PoolVector2Array, cut_polygon : PoolVector2Arr
 	var shape_infos : Array = []
 	if cut_info.final and cut_info.final.size() > 0:
 		for shape in cut_info.final:
-			var shape_area : float = PolygonLib.getPolygonArea(shape)
+			var triangulation : Dictionary = PolygonLib.triangulatePolygon(shape)
+			var shape_area : float = triangulation.area#PolygonLib.getPolygonArea(shape)
 			if shape_area < cut_min_area:
 				var fracture_info : Array = fractureDelaunay(shape, source_trans_global.get_origin(), 0.0, fractures, shard_min_area)
 				fracture_infos.append(fracture_info)
 				continue
 
-			var shape_info : Dictionary = PolygonLib.getShapeInfo(source_trans_global, shape, false)
-			shape_info.area = shape_area
+			var shape_info : Dictionary = PolygonLib.getShapeInfoSimple(source_trans_global, shape, triangulation)
 			shape_infos.append(shape_info)
 
 	return {"shapes" : shape_infos, "fractures" : fracture_infos}

polygon2d-fracture/PolygonLib.gd

@@ -12,7 +12,7 @@ static func makeTriangles(poly : PoolVector2Array, triangle_points : PoolIntArra
 	var total_area : float = 0.0
 	for i in range(triangle_points.size() / 3):
 		var index : int = i * 3
-		var points : Array = [poly[triangle_points[index]], poly[triangle_points[index + 1]], poly[triangle_points[index + 2]]]
+		var points : PoolVector2Array = [poly[triangle_points[index]], poly[triangle_points[index + 1]], poly[triangle_points[index + 2]]]
 
 		var area : float = 0.0
 		if with_area:
@@ -34,7 +34,7 @@ static func makeTriangle(points : PoolVector2Array, area : float, centroid : Vec
 #triangulates a polygon and additionally calculates the centroid and area of each triangle alongside the total area of the polygon
 static func triangulatePolygon(poly : PoolVector2Array, with_area : bool = true, with_centroid : bool = true) -> Dictionary:
 	var total_area : float = 0.0
-	var triangle_points = Geometry.triangulate_polygon(poly)
+	var triangle_points : PoolIntArray = Geometry.triangulate_polygon(poly)
 	return makeTriangles(poly, triangle_points, with_area, with_centroid)
 
 #triangulates a polygon with the delaunay method and additionally calculates the centroid and area of each triangle alongside the total area of the polygon
@@ -161,7 +161,11 @@ static func getTriangleArea(points : PoolVector2Array) -> float:
 	var c : float = (points[0] - points[1]).length()
 	var s : float = (a + b + c) * 0.5
 
-	return sqrt(s * (s - a) * (s - b) * (s - c))
+	var value : float = s * (s - a) * (s - b) * (s - c)
+	if value < 0.0:
+		return 1.0
+	var area : float = sqrt(value)
+	return area
 
 
 static func getTriangleCentroid(points : PoolVector2Array) -> Vector2:
@@ -260,8 +264,8 @@ static func cutShape(source_polygon : PoolVector2Array, cut_polygon : PoolVector
 	var intersected_polygons : Array = intersectPolygons(source_polygon, cut_polygon, true)
 	if intersected_polygons.size() <= 0:
 		return {"final" : [], "intersected" : []}
-	var final_polygons : Array = clipPolygons(source_polygon, cut_polygon, true)
 
+	var final_polygons : Array = clipPolygons(source_polygon, cut_polygon, true)
 
 	return {"final" : final_polygons, "intersected" : intersected_polygons}
 
@@ -270,13 +274,18 @@ static func cutShape(source_polygon : PoolVector2Array, cut_polygon : PoolVector
 static func makeShapeInfo(centered_shape : PoolVector2Array, centroid : Vector2, world_pos : Vector2, area : float) -> Dictionary:
 	return {"centered_shape" : centered_shape, "centroid" : centroid, "world_pos" : world_pos, "area" : area}
 
-static func getShapeInfo(source_global_trans : Transform2D, source_polygon : PoolVector2Array, calculate_area : bool = false) -> Dictionary:
-	var centroid : Vector2 = calculatePolygonCentroid(source_polygon)
+static func getShapeInfo(source_global_trans : Transform2D, source_polygon : PoolVector2Array) -> Dictionary:
+	var triangulation : Dictionary = triangulatePolygon(source_polygon, true, true)
+	var centroid : Vector2 = getPolygonCentroid(triangulation.triangles, triangulation.area)
+	var centered_shape : PoolVector2Array = translatePolygon(source_polygon, -centroid)
+	return makeShapeInfo(centered_shape, centroid, source_global_trans.get_origin(), triangulation.area)# {"spawn_pos" : spawn_pos, "centered_shape" : centered_shape, "centroid" : centroid, "world_pos" : source_global_trans.get_origin()}
+
+static func getShapeInfoSimple(source_global_trans : Transform2D, source_polygon : PoolVector2Array, triangulation : Dictionary) -> Dictionary:
+	var centroid : Vector2 = getPolygonCentroid(triangulation.triangles, triangulation.area)
 	var centered_shape : PoolVector2Array = translatePolygon(source_polygon, -centroid)
-	var area : float = 0.0
-	if calculate_area:
-		area = getPolygonArea(centered_shape)
-	return makeShapeInfo(centered_shape, centroid, source_global_trans.get_origin(), area)# {"spawn_pos" : spawn_pos, "centered_shape" : centered_shape, "centroid" : centroid, "world_pos" : source_global_trans.get_origin()}
+#	print("Get shape info simple Poly: ", source_polygon, " centroid: ", centroid, "triangulation area: ", triangulation.area, " Centered Shape: ", centered_shape)
+#	print("Triangulation: ", triangulation, " Centered Shape: ", centered_shape)
+	return makeShapeInfo(centered_shape, centroid, source_global_trans.get_origin(), triangulation.area)
 
 static func getShapeSpawnPos(parent_global_trans : Transform2D, centroid : Vector2, source_global_pos : Vector2) -> Vector2:
 	var spawn_pos : Vector2 = toGlobal(parent_global_trans, centroid) + source_global_pos