fastplotlib · kushalkolar · Oct 10, 2025 · Oct 2, 2025 · Oct 2, 2025 · Oct 2, 2025
@@ -30,4 +30,4 @@
 # See the "JupyterLab and IPython" section in the user guide
 if __name__ == "__main__":
     print(__doc__)
-    fpl.loop.run()
+    fpl.loop.run()
@@ -23,7 +23,8 @@
     data=data[:, :-1],
     sizes=6,
     alpha=0.7,
-    colors=colors  # use colors from the list of strings
+    alpha_mode="weighted_blend",  # blend overlapping dots
+    colors=colors,  # use colors from the list of strings
 )
 
 figure.show()

@@ -183,14 +183,22 @@ def __init__(
         }
 
         # create ruler for each dim
-        self._x = pygfx.Ruler(alpha_mode="solid", **x_kwargs)
-        self._y = pygfx.Ruler(alpha_mode="solid", **y_kwargs)
-        self._z = pygfx.Ruler(alpha_mode="solid", **z_kwargs)
+        self._x = pygfx.Ruler(
+            alpha_mode="solid", render_queue=RenderQueue.axes, **x_kwargs
+        )
+        self._y = pygfx.Ruler(
+            alpha_mode="solid", render_queue=RenderQueue.axes, **y_kwargs
+        )
+        self._z = pygfx.Ruler(
+            alpha_mode="solid", render_queue=RenderQueue.axes, **z_kwargs
+        )
 
         # We render the lines and ticks as solid, but enable aa for text for prettier glyphs
         for ruler in self._x, self._y, self._z:
+            ruler.line.material.depth_compare = "<="
+            ruler.points.material.depth_compare = "<="
+            ruler.text.material.depth_compare = "<="
             ruler.text.material.alpha_mode = "auto"
-            ruler.text.material.render_queue = RenderQueue.auto + 50
             ruler.text.material.aa = True
 
         self._offset = offset

@@ -324,9 +324,6 @@ def add_linear_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place selector above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
 
     def add_linear_region_selector(
@@ -402,9 +399,6 @@ def add_linear_region_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
 
     def add_rectangle_selector(
@@ -447,9 +441,6 @@ def add_rectangle_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
 
     def add_polygon_selector(
@@ -485,7 +476,4 @@ def add_polygon_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
@@ -96,6 +96,7 @@ def __init__(
 
         if thickness < 1.1:
             MaterialCls = pygfx.LineThinMaterial
+            aa = True
         else:
             MaterialCls = pygfx.LineMaterial
 
@@ -110,6 +111,7 @@ def __init__(
                 color=self.colors,
                 pick_write=True,
                 thickness_space=self.size_space,
+                depth_compare="<=",
             )
         else:
             material = MaterialCls(
@@ -118,6 +120,7 @@ def __init__(
                 color_mode="vertex",
                 pick_write=True,
                 thickness_space=self.size_space,
+                depth_compare="<=",
             )
             geometry = pygfx.Geometry(
                 positions=self._data.buffer, colors=self._colors.buffer
@@ -179,9 +182,6 @@ def add_linear_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place selector above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
 
     def add_linear_region_selector(
@@ -238,9 +238,6 @@ def add_linear_region_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place selector below this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] - 1)
-
         # PlotArea manages this for garbage collection etc. just like all other Graphics
         # so we should only work with a proxy on the user-end
         return selector

@@ -378,9 +378,6 @@ def add_linear_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place selector above this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] + 1)
-
         return selector
 
     def add_linear_region_selector(
@@ -435,9 +432,6 @@ def add_linear_region_selector(
 
         self._plot_area.add_graphic(selector, center=False)
 
-        # place selector below this graphic
-        selector.offset = selector.offset + (0.0, 0.0, self.offset[-1] - 1)
-
         # PlotArea manages this for garbage collection etc. just like all other Graphics
         # so we should only work with a proxy on the user-end
         return selector

@@ -97,10 +97,7 @@ def __init__(
         aa = kwargs.get("alpha_mode", "auto") in ("blend", "weighted_blend")
 
         geo_kwargs = {"positions": self._data.buffer}
-        material_kwargs = dict(
-            pick_write=True,
-            aa=aa,
-        )
+        material_kwargs = dict(pick_write=True, aa=aa, depth_compare="<=")
         self._size_space = SizeSpace(size_space)
 
         if uniform_color:

@@ -10,6 +10,7 @@
 
 from ._utils import create_controller
 from ..graphics._base import Graphic
+from ..graphics import ImageGraphic
 from ..graphics.selectors._base_selector import BaseSelector
 from ._graphic_methods_mixin import GraphicMethodsMixin
 from ..legends import Legend
@@ -394,6 +395,29 @@ def remove_animation(self, func):
         if func in self._animate_funcs_post:
             self._animate_funcs_post.remove(func)
 
+    def _sort_images_by_depth(self):
+        """
+        In general, we want to avoid setting the offset of a graphic, because the
+        z-dimension may actually mean something; we cannot know whether the user is
+        building a 3D scene or not. We could check whether the 3d dimension of line/point data
+        is all zeros, but maybe this is intended, and *other* graphics in the same scene
+        may be actually 3D. We could check camera.fov being zero, but maybe the user
+        switches to a 3D camera later, or uses a 3D orthographic camera.
+
+        The one exception, kindof, is images, which are inherently 2D, and for which
+        layering helps a lot to get things rendered correctly. So we basically layer the
+        images, in the order that they were added, pushing older images backwards (away
+        from the camera).
+        """
+        count = 0
+        for graphic in self._graphics:
+            if isinstance(graphic, ImageGraphic):
+                count += 1
+                auto_depth = -count
+                user_changed_depth = graphic.offset[2] % 1 > 0.0  # i.e. is not integer
+                if not user_changed_depth:
+                    graphic.offset = (*graphic.offset[:-1], auto_depth)
+
     def add_graphic(self, graphic: Graphic, center: bool = True):
         """
         Add a Graphic to the scene
@@ -416,10 +440,8 @@ def add_graphic(self, graphic: Graphic, center: bool = True):
 
         self._add_or_insert_graphic(graphic=graphic, center=center, action="add")
 
-        if self.camera.fov == 0:
-            # for orthographic positions stack objects along the z-axis
-            # for perspective projections we assume the user wants full 3D control
-            graphic.offset = (*graphic.offset[:-1], len(self))
+        if isinstance(graphic, ImageGraphic):
+            self._sort_images_by_depth()
 
     def insert_graphic(
         self,
@@ -458,17 +480,14 @@ def insert_graphic(
             graphic=graphic, center=center, action="insert", index=index
         )
 
-        if self.camera.fov == 0:
-            # for orthographic positions stack objects along the z-axis
-            # for perspective projections we assume the user wants full 3D control
-            if auto_offset:
-                graphic.offset = (*graphic.offset[:-1], index)
+        if isinstance(graphic, ImageGraphic):
+            self._sort_images_by_depth()
 
     def _add_or_insert_graphic(
         self,
         graphic: Graphic,
         center: bool = True,
-        action: str = Literal["insert", "add"],
+        action: Literal["insert", "add"] = "add",
         index: int = 0,
     ):
         """Private method to handle inserting or adding a graphic to a PlotArea."""

@@ -71,11 +71,9 @@ def __init__(
         # construct Line WorldObject
         data = np.array([[0, 0, 0], [3, 0, 0]], dtype=np.float32)
 
-        material = pygfx.LineMaterial
-
         self._line_world_object = pygfx.Line(
             geometry=pygfx.Geometry(positions=data),
-            material=material(
+            material=pygfx.LineMaterial(
                 alpha_mode="blend",
                 render_queue=RenderQueue.overlay,
                 thickness=8,
@@ -112,7 +110,6 @@ def __init__(
         self._label_world_object.world.x = position[0] + 10
 
         self.world_object.world.y = position[1]
-        self.world_object.world.z = 2
 
         self.world_object.add_event_handler(
             partial(self._highlight_graphic, graphic), "click"

@@ -9,6 +9,7 @@ class RenderQueue(IntEnum):
     auto = 2600
     transparent = 3000
     overlay = 4000
-    # For selectors we use a render_queue of 3500, which is at the end of what is considered the group of transparent objects.
-    # So it's rendered later than the normal scene (2000 - 3000), but before overlays like legends and tooltips.
-    selector = 3500
+    # For axes and selectors we use a higher render_queue, so they get rendered later than
+    # the graphics. Axes (rulers) have depth_compare '<=' and selectors don't compare depth.
+    axes = 3400  # still in 'object' group
+    selector = 3600  # considered in 'overlay' group