Put the axis helpers on the topmost z-layer so there is no z-fighting

cq_editor/main_window.py

@@ -456,6 +456,9 @@ def prepare_actions(self):
         self.components["object_tree"].sigAISObjectsSelected.connect(
             self.components["viewer"].set_selected
         )
+        self.components["object_tree"].sigHelpersResized.connect(
+            self.components["viewer"].redisplay
+        )
 
         self.components["viewer"].sigObjectSelected.connect(
             self.components["object_tree"].handleGraphicalSelection

cq_editor/widgets/editor.py

@@ -485,6 +485,10 @@ def _file_changed(self):
         # neovim writes a file by removing it first so must re-add each time
         self._watch_paths()
 
+        # QFileSystemWater reports deletions as changes
+        if not Path(self._filename).exists():
+            return
+
         # Save the current cursor position and selection
         cursor = self.textCursor()
         cursor_position = cursor.position()

cq_editor/widgets/object_tree.py

@@ -11,8 +11,10 @@
 from pyqtgraph.parametertree import Parameter, ParameterTree
 
 from OCP.AIS import AIS_Line
-from OCP.Geom import Geom_Line
-from OCP.gp import gp_Dir, gp_Pnt, gp_Ax1
+from OCP.Geom import Geom_CartesianPoint
+from OCP.gp import gp_Pnt
+from OCP.Graphic3d import Graphic3d_ZLayerId_Topmost
+from OCP.Bnd import Bnd_Box
 
 from ..mixins import ComponentMixin
 from ..icons import icon
@@ -27,6 +29,9 @@
 from .viewer import DEFAULT_FACE_COLOR
 from ..utils import splitter, layout, get_save_filename
 
+# Default size of the axis helper lines half-length
+DEFAULT_AXIS_HALF_LEN = 100.0
+
 
 class TopTreeItem(QTreeWidgetItem):
 
@@ -135,6 +140,7 @@ class ObjectTree(QWidget, ComponentMixin):
     sigAISObjectsSelected = pyqtSignal(list)
     sigItemChanged = pyqtSignal(QTreeWidgetItem, int)
     sigObjectPropertiesChanged = pyqtSignal()
+    sigHelpersResized = pyqtSignal(list)
 
     def __init__(self, parent):
 
@@ -197,6 +203,37 @@ def __init__(self, parent):
 
         self.prepareLayout()
 
+    def _axis_points(self, direction, halfLen):
+        """Calculates the points needed to draw the axis helper lines"""
+        p1 = Geom_CartesianPoint(gp_Pnt(*(-halfLen * d for d in direction)))
+        p2 = Geom_CartesianPoint(gp_Pnt(*(halfLen * d for d in direction)))
+
+        return p1, p2
+
+    def _rescale_helpers(self):
+        """Called to resize the axis helper lines to the model's bounding box."""
+
+        # Bounding box over all currently displayed CQ shapes
+        bbox = Bnd_Box()
+        for i in range(self.CQ.childCount()):
+            ais = self.CQ.child(i).ais
+            if ais is not None:
+                bbox.Add(ais.BoundingBox())
+
+        if bbox.IsVoid():
+            halfLen = DEFAULT_AXIS_HALF_LEN
+        else:
+            halfLen = 2.0 * bbox.CornerMin().Distance(bbox.CornerMax())
+
+        resized = []
+        for item, direction in self._helper_dirs:
+            p1, p2 = self._axis_points(direction, halfLen)
+            item.ais.SetPoints(p1, p2)  # update geometry in place
+            resized.append(item.ais)
+
+        if resized:
+            self.sigHelpersResized.emit(resized)
+
     def prepareMenu(self):
 
         self.tree.setContextMenuPolicy(Qt.CustomContextMenu)
@@ -231,20 +268,22 @@ def toolbarActions(self):
         return self._toolbar_actions
 
     def addLines(self):
-
-        origin = (0, 0, 0)
         ais_list = []
+        self._helper_dirs = []  # (item, direction) pairs, for later rescaling
 
         for name, color, direction in zip(
             ("X", "Y", "Z"),
             ("red", "lawngreen", "blue"),
             ((1, 0, 0), (0, 1, 0), (0, 0, 1)),
         ):
-            line_placement = Geom_Line(gp_Ax1(gp_Pnt(*origin), gp_Dir(*direction)))
-            line = AIS_Line(line_placement)
+            p1, p2 = self._axis_points(direction, DEFAULT_AXIS_HALF_LEN)
+            line = AIS_Line(p1, p2)
             line.SetColor(to_occ_color(color))
+            line.SetZLayer(Graphic3d_ZLayerId_Topmost)
 
-            self.Helpers.addChild(ObjectTreeItem(name, ais=line))
+            item = ObjectTreeItem(name, ais=line)
+            self.Helpers.addChild(item)
+            self._helper_dirs.append((item, direction))
 
             ais_list.append(line)
 
@@ -309,6 +348,8 @@ def addObjects(self, objects, clean=False, root=None):
         else:
             self.sigObjectsAdded[list].emit(ais_list)
 
+        self._rescale_helpers()
+
     @pyqtSlot(object, str, object)
     def addObject(self, obj, name="", options=None):
 

cq_editor/widgets/viewer.py

@@ -8,8 +8,16 @@
     Graphic3d_StereoMode,
     Graphic3d_NOM_JADE,
     Graphic3d_MaterialAspect,
+    Graphic3d_ZLayerId_Topmost,
+)
+from OCP.AIS import (
+    AIS_Shaded,
+    AIS_WireFrame,
+    AIS_ColoredShape,
+    AIS_Axis,
+    AIS_Line,
+    AIS_ListOfInteractive,
 )
-from OCP.AIS import AIS_Shaded, AIS_WireFrame, AIS_ColoredShape, AIS_Axis
 from OCP.Aspect import Aspect_GDM_Lines, Aspect_GT_Rectangular
 from OCP.Quantity import (
     Quantity_NOC_BLACK as BLACK,
@@ -18,6 +26,7 @@
 )
 from OCP.Geom import Geom_Axis1Placement
 from OCP.gp import gp_Ax3, gp_Dir, gp_Pnt, gp_Ax1
+from OCP.Bnd import Bnd_Box
 
 from ..utils import layout, get_save_filename
 from ..mixins import ComponentMixin
@@ -119,6 +128,7 @@ def __init__(self, parent=None):
         )
 
         self.setup_default_drawer()
+        self.setup_helper_layer()
         self.updatePreferences()
 
     def setup_default_drawer(self):
@@ -135,6 +145,16 @@ def setup_default_drawer(self):
         line_aspect.SetWidth(DEFAULT_EDGE_WIDTH)
         line_aspect.SetColor(DEFAULT_EDGE_COLOR)
 
+    def setup_helper_layer(self):
+        """
+        Set up a render layer specifically for the axis helper lines.
+        """
+        viewer = self.canvas.context.CurrentViewer()
+        settings = viewer.ZLayerSettings(Graphic3d_ZLayerId_Topmost)
+        settings.SetEnableDepthTest(False)  # lines never depth-compare with the model
+        settings.SetEnableDepthWrite(False)  # lines never write into the depth buffer
+        viewer.SetZLayerSettings(Graphic3d_ZLayerId_Topmost, settings)
+
     def updatePreferences(self, *args):
 
         color1 = to_occ_color(self.preferences["Background color"])
@@ -314,6 +334,13 @@ def update_item(self, item, col):
         else:
             ctx.Erase(item.ais, True)
 
+    @pyqtSlot(list)
+    def redisplay(self, ais_list):
+        ctx = self._get_context()
+        for ais in ais_list:
+            if ctx.IsDisplayed(ais):
+                ctx.Redisplay(ais, True)
+
     @pyqtSlot(list)
     def remove_items(self, ais_items):
 
@@ -327,8 +354,23 @@ def redraw(self):
         self._get_viewer().Redraw()
 
     def fit(self):
+        ctx = self._get_context()
+        view = self.canvas.view
+
+        displayed = AIS_ListOfInteractive()
+        ctx.DisplayedObjects(displayed)
 
-        self.canvas.view.FitAll()
+        # Accumulate the bounding box for displayed objects
+        bbox = Bnd_Box()
+        for ais in displayed:
+            if not isinstance(ais, AIS_Line):
+                bbox.Add(ais.BoundingBox())
+
+        # If nothing but the axis helpers are visible, fit to default
+        if bbox.IsVoid():
+            view.FitAll()
+        else:
+            view.FitAll(bbox, 0.01, True)
 
     def iso_view(self):
 

tests/test_app.py

@@ -211,7 +211,7 @@ def test_render(main):
     log = win.components["log"]
 
     # enable CQ reloading
-    debugger.preferences["Reload CQ"] = True
+    debugger.preferences["Reload CQ"] = False
 
     # check that object was rendered
     assert obj_tree_comp.CQ.childCount() == 1