Recalculate the start / end elements when the layer is changed instead of on render

About with larger models, about 30-40% of the time of the render was spent on this.

plugins/SimulationView/SimulationPass.py

@@ -93,7 +93,6 @@ class SimulationPass(RenderPass):
         self.bind()
 
         tool_handle_batch = RenderBatch(self._tool_handle_shader, type = RenderBatch.RenderType.Overlay, backface_cull = True)
-        active_build_plate = Application.getInstance().getMultiBuildPlateModel().activeBuildPlate
         head_position = None  # Indicates the current position of the print head
         nozzle_node = None
 
@@ -113,16 +112,11 @@ class SimulationPass(RenderPass):
 
                 # Render all layers below a certain number as line mesh instead of vertices.
                 if self._layer_view._current_layer_num > -1 and ((not self._layer_view._only_show_top_layers) or (not self._layer_view.getCompatibilityMode())):
-                    start = 0
+                    start = self._layer_view.start_elements_index
-                    end = 0
+                    end = self._layer_view.end_elements_index
-                    element_counts = layer_data.getElementCounts()
-                    for layer in sorted(element_counts.keys()):
-                        # In the current layer, we show just the indicated paths
-                        if layer == self._layer_view._current_layer_num:
-                            # We look for the position of the head, searching the point of the current path
                     index = self._layer_view._current_path_num
                     offset = 0
-                            for polygon in layer_data.getLayer(layer).polygons:
+                    for polygon in layer_data.getLayer(self._layer_view._current_layer_num).polygons:
                         # The size indicates all values in the two-dimension array, and the second dimension is
                         # always size 3 because we have 3D points.
                         if index >= polygon.data.size // 3 - offset:
@@ -130,12 +124,9 @@ class SimulationPass(RenderPass):
                             offset = 1  # This is to avoid the first point when there is more than one polygon, since has the same value as the last point in the previous polygon
                             continue
                         # The head position is calculated and translated
-                                head_position = Vector(polygon.data[index+offset][0], polygon.data[index+offset][1], polygon.data[index+offset][2]) + node.getWorldPosition()
+                        head_position = Vector(polygon.data[index + offset][0], polygon.data[index + offset][1],
+                                               polygon.data[index + offset][2]) + node.getWorldPosition()
                         break
-                            break
-                        if self._layer_view._minimum_layer_num > layer:
-                            start += element_counts[layer]
-                        end += element_counts[layer]
 
                     # Calculate the range of paths in the last layer
                     current_layer_start = end

plugins/SimulationView/SimulationView.py

@@ -71,6 +71,8 @@ class SimulationView(CuraView):
         self._max_paths = 0
         self._current_path_num = 0
         self._minimum_path_num = 0
+        self.start_elements_index = 0
+        self.end_elements_index = 0
         self.currentLayerNumChanged.connect(self._onCurrentLayerNumChanged)
 
         self._busy = False
@@ -243,6 +245,7 @@ class SimulationView(CuraView):
                 self._minimum_layer_num = self._current_layer_num
 
             self._startUpdateTopLayers()
+            self.recalculateStartEndElements()
 
             self.currentLayerNumChanged.emit()
 
@@ -257,7 +260,7 @@ class SimulationView(CuraView):
                 self._current_layer_num = self._minimum_layer_num
 
             self._startUpdateTopLayers()
-
+            self.recalculateStartEndElements()
             self.currentLayerNumChanged.emit()
 
     def setPath(self, value: int) -> None:
@@ -359,6 +362,24 @@ class SimulationView(CuraView):
             return 0.0 # If it's still max-float, there are no measurements. Use 0 then.
         return self._min_thickness
 
+    def recalculateStartEndElements(self):
+        self.start_elements_index = 0
+        self.end_elements_index = 0
+        scene = self.getController().getScene()
+        for node in DepthFirstIterator(scene.getRoot()):  # type: ignore
+            layer_data = node.callDecoration("getLayerData")
+            if not layer_data:
+                continue
+
+            # Found a the layer data!
+            element_counts = layer_data.getElementCounts()
+            for layer in sorted(element_counts.keys()):
+                if layer == self._current_layer_num:
+                    break
+                if self._minimum_layer_num > layer:
+                    self.start_elements_index += element_counts[layer]
+                self.end_elements_index += element_counts[layer]
+
     def getMaxThickness(self) -> float:
         return self._max_thickness