for engrave: skip the top layer (no penetration, yet)

pycam/Plugins/ProcessStrategies.py

@@ -177,7 +177,7 @@ class ProcessStrategyEngraving(pycam.Plugins.PluginBase):
                 step_width=(tool_radius / 4.0),
                 milling_style=process["parameters"]["milling_style"],
                 pocketing_type=process["parameters"]["pocketing_type"],
-                callback=progress.update)
+                skip_first_layer=True, callback=progress.update)
         progress.finish()
         return path_generator, motion_grid
 

pycam/Toolpath/MotionGrid.py

@@ -400,7 +400,7 @@ def _get_sorted_polygons(models, callback=None):
 def get_lines_grid(models, (low, high), layer_distance, line_distance=None,
         step_width=None, milling_style=MILLING_STYLE_CONVENTIONAL,
         start_position=START_Z, pocketing_type=POCKETING_TYPE_NONE,
-        callback=None):
+        skip_first_layer=False, callback=None):
     # the lower limit is never below the model
     polygons = _get_sorted_polygons(models, callback=callback)
     if polygons:
@@ -433,6 +433,9 @@ def get_lines_grid(models, (low, high), layer_distance, line_distance=None,
                 reverse=bool(start_position & START_Z))
     # turn the generator into a list - otherwise the slicing fails
     layers = list(layers)
+    # engrave ignores the top layer
+    if skip_first_layer and (len(layers) > 1):
+        layers = layers[1:]
     last_z = None
     if layers:
         # the upper layers are used for PushCutter operations