Take into account that can be empty layers below the model when the

setting Remove empty layers is disabled.

The empty layers are skipped if they are at the bottom. Also keeps the
models printed with raft showing correclty.

Contributes to CURA-5768.

1 files changed, 23 insertions, 10 deletions

diff --git a/plugins/CuraEngineBackend/ProcessSlicedLayersJob.py b/plugins/CuraEngineBackend/ProcessSlicedLayersJob.py
index 3953625c7e..594bf3a43e 100644
--- a/plugins/CuraEngineBackend/ProcessSlicedLayersJob.py
+++ b/plugins/CuraEngineBackend/ProcessSlicedLayersJob.py
@@ -2,6 +2,7 @@
 #Cura is released under the terms of the LGPLv3 or higher.
 
 import gc
+import sys
 
 from UM.Job import Job
 from UM.Application import Application
@@ -95,23 +96,35 @@ class ProcessSlicedLayersJob(Job):
         layer_count = len(self._layers)
 
         # Find the minimum layer number
+        # When disabling the remove empty first layers setting, the minimum layer number will be a positive
+        # value. In that case the first empty layers will be discarded and start processing layers from the
+        # first layer with data.
         # When using a raft, the raft layers are sent as layers < 0. Instead of allowing layers < 0, we
-        # instead simply offset all other layers so the lowest layer is always 0. It could happens that
-        # the first raft layer has value -8 but there are just 4 raft (negative) layers.
-        min_layer_number = 0
+        # simply offset all other layers so the lowest layer is always 0. It could happens that the first
+        # raft layer has value -8 but there are just 4 raft (negative) layers.
+        min_layer_number = sys.maxsize
         negative_layers = 0
         for layer in self._layers:
-            if layer.id < min_layer_number:
-                min_layer_number = layer.id
-            if layer.id < 0:
-                negative_layers += 1
+            if layer.repeatedMessageCount("path_segment") > 0:
+                if layer.id < min_layer_number:
+                    min_layer_number = layer.id
+                if layer.id < 0:
+                    negative_layers += 1
 
         current_layer = 0
 
         for layer in self._layers:
-            # Negative layers are offset by the minimum layer number, but the positive layers are just
-            # offset by the number of negative layers so there is no layer gap between raft and model
-            abs_layer_number = layer.id + abs(min_layer_number) if layer.id < 0 else layer.id + negative_layers
+            # If the layer is below the minimum, it means that there is no data, so that we don't create a layer
+            # data. However, if there are empty layers in between, we compute them.
+            if layer.id < min_layer_number:
+                continue
+
+            # Layers are offset by the minimum layer number. In case the raft (negative layers) is being used,
+            # then the absolute layer number is adjusted by removing the empty layers that can be in between raft
+            # and the model
+            abs_layer_number = layer.id - min_layer_number
+            if layer.id >= 0 and negative_layers != 0:
+                abs_layer_number += (min_layer_number + negative_layers)
 
             layer_data.addLayer(abs_layer_number)
             this_layer = layer_data.getLayer(abs_layer_number)