Fixed bug that caused crash when object was entirely below platform

cura/ConvexHullJob.py

@@ -38,7 +38,6 @@ class ConvexHullJob(Job):
             vertex_data = mesh.getTransformed(self._node.getWorldTransformation()).getVertices()
             # Don't use data below 0. TODO; We need a better check for this as this gives poor results for meshes with long edges.
             vertex_data = vertex_data[vertex_data[:,1]>0]
-
             hull = Polygon(numpy.rint(vertex_data[:, [0, 2]]).astype(int))
 
         # First, calculate the normal convex hull around the points

cura/ConvexHullNode.py

@@ -30,14 +30,14 @@ class ConvexHullNode(SceneNode):
         self._hull = hull
 
         hull_points = self._hull.getPoints()
-        center = (hull_points.min(0) + hull_points.max(0)) / 2.0
-
         mesh = MeshData()
-        mesh.addVertex(center[0], 0.1, center[1])
-
+        if len(hull_points) > 3:
+            center = (hull_points.min(0) + hull_points.max(0)) / 2.0
+            mesh.addVertex(center[0], 0.1, center[1])
+        else: #Hull has not enough points
+            return
         for point in hull_points:
             mesh.addVertex(point[0], 0.1, point[1])
-
         indices = []
         for i in range(len(hull_points) - 1):
             indices.append([0, i + 1, i + 2])

cura/PlatformPhysics.py

@@ -115,6 +115,8 @@ class PlatformPhysics:
                     move_vector.setZ(overlap[1] * 1.1)
             convex_hull = node.callDecoration("getConvexHull")
             if convex_hull:
+                if not convex_hull.isValid():
+                    return
                 # Check for collisions between disallowed areas and the object
                 for area in self._build_volume.getDisallowedAreas():
                     overlap = convex_hull.intersectsPolygon(area)