Fetch count from simple property instead of recalculation.

Polygons don't change when in layer-view. There's already an analogous elementCount property anyway, so a vertexCount property can't do much harm. Just keep in mind that when the polygons are altered, it should be either done via build, or the lineMeshXXXCount methods should be used instead.

cura/Layer.py

@@ -15,6 +15,7 @@ class Layer:
         self._height = 0.0
         self._thickness = 0.0
         self._polygons = []  # type: List[LayerPolygon]
+        self._vertex_count = 0
         self._element_count = 0
 
     @property
@@ -29,6 +30,10 @@ class Layer:
     def polygons(self) -> List[LayerPolygon]:
         return self._polygons
 
+    @property
+    def vertexCount(self):
+        return self._vertex_count
+
     @property
     def elementCount(self):
         return self._element_count
@@ -64,11 +69,13 @@ class Layer:
     def build(self, vertex_offset, index_offset, vertices, colors, line_dimensions, feedrates, extruders, line_types, indices):
         result_vertex_offset = vertex_offset
         result_index_offset = index_offset
+        self._vertex_count = 0
         self._element_count = 0
         for polygon in self._polygons:
             polygon.build(result_vertex_offset, result_index_offset, vertices, colors, line_dimensions, feedrates, extruders, line_types, indices)
             result_vertex_offset += polygon.lineMeshVertexCount()
             result_index_offset += polygon.lineMeshElementCount()
+            self._vertex_count += polygon.vertexCount
             self._element_count += polygon.elementCount
 
         return result_vertex_offset, result_index_offset

cura/LayerPolygon.py

@@ -187,6 +187,10 @@ class LayerPolygon:
     def data(self):
         return self._data
 
+    @property
+    def vertexCount(self):
+        return self._vertex_end - self._vertex_begin
+
     @property
     def elementCount(self):
         return (self._index_end - self._index_begin) * 2  # The range of vertices multiplied by 2 since each vertex is used twice

plugins/SimulationView/SimulationPass.py

@@ -162,7 +162,7 @@ class SimulationPass(RenderPass):
                                 head_position = Vector(polygon.data[index+offset][0], polygon.data[index+offset][1], polygon.data[index+offset][2]) + node.getWorldPosition()
                                 break
                             break
-                        end += layer_data.getLayer(layer).lineMeshVertexCount()
+                        end += layer_data.getLayer(layer).vertexCount
                         if layer < self._layer_view._minimum_layer_num:
                             start = end