Add primitive picking filters for Mesh and Markers visuals

examples/scene/face_picking.py

@@ -0,0 +1,149 @@
+# -*- coding: utf-8 -*-
+# vispy: gallery 30
+# -----------------------------------------------------------------------------
+# Copyright (c) Vispy Development Team. All Rights Reserved.
+# Distributed under the (new) BSD License. See LICENSE.txt for more info.
+# -----------------------------------------------------------------------------
+"""
+Picking Faces from a Mesh
+=========================
+
+Demonstrates how to identify (pick) individual faces on a mesh.
+
+Arguments:
+* --mesh - Path to a mesh file (OBJ/OBJ.GZ) [optional]
+
+Controls:
+* p  - Toggle face picking view - shows the colors encoding face ID
+* r  - Clear painted faces
+* s  - Cycle shading modes (None, 'flat', 'smooth')
+* w  - Toggle wireframe
+"""
+import argparse
+import itertools
+import time
+
+import numpy as np
+
+from vispy import app, scene
+from vispy.io import read_mesh, load_data_file
+from vispy.scene.visuals import Mesh
+from vispy.scene import transforms
+from vispy.visuals.filters import ShadingFilter, WireframeFilter, FacePickingFilter
+
+
+parser = argparse.ArgumentParser()
+default_mesh = load_data_file('orig/triceratops.obj.gz')
+parser.add_argument('--mesh', default=default_mesh)
+args, _ = parser.parse_known_args()
+
+vertices, faces, _normals, _texcoords = read_mesh(args.mesh)
+
+canvas = scene.SceneCanvas(keys='interactive', bgcolor='white')
+view = canvas.central_widget.add_view()
+
+view.camera = 'arcball'
+view.camera.depth_value = 1e3
+
+# Create a colored `MeshVisual`.
+face_colors = np.tile((0.5, 0.0, 0.5, 1.0), (len(faces), 1))
+mesh = Mesh(
+    vertices,
+    faces,
+    face_colors=face_colors.copy()
+)
+mesh.transform = transforms.MatrixTransform()
+mesh.transform.rotate(90, (1, 0, 0))
+mesh.transform.rotate(-45, (0, 0, 1))
+view.add(mesh)
+
+# Use filters to affect the rendering of the mesh.
+wireframe_filter = WireframeFilter()
+shading_filter = ShadingFilter()
+face_picking_filter = FacePickingFilter()
+mesh.attach(wireframe_filter)
+mesh.attach(shading_filter)
+mesh.attach(face_picking_filter)
+
+
+def attach_headlight(view):
+    light_dir = (0, 1, 0, 0)
+    shading_filter.light_dir = light_dir[:3]
+    initial_light_dir = view.camera.transform.imap(light_dir)
+
+    @view.scene.transform.changed.connect
+    def on_transform_change(event):
+        transform = view.camera.transform
+        shading_filter.light_dir = transform.map(initial_light_dir)[:3]
+
+
+attach_headlight(view)
+
+shading = itertools.cycle(("flat", "smooth", None))
+shading_filter.shading = next(shading)
+
+
+throttle = time.monotonic()
+
+
+@canvas.events.mouse_move.connect
+def on_mouse_move(event):
+    global throttle
+    # throttle mouse events to 50ms
+    if time.monotonic() - throttle < 0.05:
+        return
+    throttle = time.monotonic()
+
+    # adjust the event position for hidpi screens
+    render_size = tuple(d * canvas.pixel_scale for d in canvas.size)
+    x_pos = event.pos[0] * canvas.pixel_scale
+    y_pos = render_size[1] - (event.pos[1] * canvas.pixel_scale)
+
+    # render a small patch around the mouse cursor
+    restore_state = not face_picking_filter.enabled
+    face_picking_filter.enabled = True
+    mesh.update_gl_state(blend=False)
+    picking_render = canvas.render(
+        region=(x_pos - 1, y_pos - 1, 3, 3),
+        size=(3, 3),
+        bgcolor=(0, 0, 0, 0),
+        alpha=True,
+    )
+    if restore_state:
+        face_picking_filter.enabled = False
+    mesh.update_gl_state(blend=not face_picking_filter.enabled)
+
+    # unpack the face index from the color in the center pixel
+    face_idx = (picking_render.view(np.uint32) - 1)[1, 1, 0]
+
+    if face_idx > 0 and face_idx < len(face_colors):
+        # this may be less safe, but it's faster than set_data
+        mesh.mesh_data._face_colors_indexed_by_faces[face_idx] = (0, 1, 0, 1)
+        mesh.mesh_data_changed()
+
+
+@canvas.events.key_press.connect
+def on_key_press(event):
+    if event.key == 'p':
+        face_picking_filter.enabled = not face_picking_filter.enabled
+        mesh.update_gl_state(blend=not face_picking_filter.enabled)
+        mesh.update()
+
+    if event.key == 'r':
+        mesh.set_data(vertices, faces, face_colors=face_colors)
+
+    if event.key == 's':
+        shading_filter.shading = next(shading)
+        mesh.update()
+
+    if event.key == 'w':
+        wireframe_filter.enabled = not wireframe_filter.enabled
+        mesh.update()
+
+
+canvas.show()
+
+
+if __name__ == "__main__":
+    print(__doc__)
+    app.run()

examples/scene/marker_picking.py

@@ -0,0 +1,155 @@
+# -*- coding: utf-8 -*-
+# vispy: gallery 30
+# -----------------------------------------------------------------------------
+# Copyright (c) Vispy Development Team. All Rights Reserved.
+# Distributed under the (new) BSD License. See LICENSE.txt for more info.
+# -----------------------------------------------------------------------------
+"""
+Picking Markers
+===============
+
+Demonstrates how to identify (pick) markers. Hover markers to change their
+symbol and color.
+
+Controls:
+* p  - Toggle picking view - shows the colors encoding marker ID
+* r  - Reset marker symbols and colors
+"""
+import random
+import time
+import numpy as np
+from scipy.constants import golden as GOLDEN
+
+from vispy import app, scene
+from vispy.scene.visuals import Markers
+from vispy.visuals.filters import MarkerPickingFilter
+
+canvas = scene.SceneCanvas(keys='interactive', bgcolor='black')
+view = canvas.central_widget.add_view(camera="panzoom")
+view.camera.rect = (-1, -1, 2, 2)
+
+# floret pattern
+n = 10_000
+radius = np.linspace(0, 0.9, n)**0.6  # prevent extreme density at center
+theta = np.arange(n) * GOLDEN
+pos = np.column_stack([radius * np.cos(theta), radius * np.sin(theta)])
+
+COLORS = [
+    (1, 0, 0, 1),  # red
+    (1, 0.5, 0, 1),  # orange
+    (1, 1, 0, 1),  # yellow
+    (0, 1, 0, 1),  # green
+    (0, 0, 1, 1),  # blue
+    (0.29, 0, 0.51, 1),  # indigo
+    (0.93, 0.51, 0.93, 1),  # violet
+]
+
+colors = np.zeros((n, 4), dtype=np.float32)
+colors[:, 0] = 1  # red
+colors[:, -1] = 1  # alpha
+_colors = colors.copy()
+
+symbols = list(Markers._symbol_shader_values.keys())
+symbols_ring = dict(zip(symbols, symbols[1:]))
+symbols_ring[symbols[-1]] = symbols[0]
+
+EDGE_COLOR = "white"
+MARKER_SIZE = 0.0125
+EDGE_WDITH = MARKER_SIZE / 10
+
+markers = Markers(
+    pos=pos,
+    edge_color=EDGE_COLOR,
+    face_color=colors,
+    size=MARKER_SIZE,
+    edge_width=EDGE_WDITH,
+    scaling="scene",
+)
+markers.update_gl_state(depth_test=True)
+view.add(markers)
+
+# Use filters to affect the rendering of the mesh.
+picking_filter = MarkerPickingFilter()
+markers.attach(picking_filter)
+
+
+@view.events.connect
+def on_viewbox_change(event):
+    # workaround for vispy/#2501
+    markers.update_gl_state(blend=not picking_filter.enabled)
+
+
+throttle = time.monotonic()
+
+
+@canvas.events.mouse_move.connect
+def on_mouse_move(event):
+    global throttle
+    # throttle mouse events to 50ms
+    if time.monotonic() - throttle < 0.05:
+        return
+    throttle = time.monotonic()
+
+    # adjust the event position for hidpi screens
+    render_size = tuple(d * canvas.pixel_scale for d in canvas.size)
+    x_pos = event.pos[0] * canvas.pixel_scale
+    y_pos = render_size[1] - (event.pos[1] * canvas.pixel_scale)
+
+    # render a small patch around the mouse cursor
+    restore_state = not picking_filter.enabled
+    picking_filter.enabled = True
+    markers.update_gl_state(blend=False)
+    picking_render = canvas.render(
+        crop=(x_pos - 2, y_pos - 2, 5, 5),
+        bgcolor=(0, 0, 0, 0),
+        alpha=True,
+    )
+    if restore_state:
+        picking_filter.enabled = False
+    markers.update_gl_state(blend=not picking_filter.enabled)
+
+    # unpack the face index from the color in the center pixel
+    marker_idx = (picking_render.view(np.uint32) - 1)[2, 2, 0]
+
+    if marker_idx >= 0 and marker_idx < len(pos):
+        new_symbols = list(markers.symbol)
+        new_symbol = symbols_ring[new_symbols[marker_idx]]
+        new_symbols[marker_idx] = new_symbol
+
+        colors[marker_idx] = random.choice(COLORS)
+        markers.set_data(
+            pos=pos,
+            edge_color=EDGE_COLOR,
+            face_color=colors,
+            size=MARKER_SIZE,
+            edge_width=EDGE_WDITH,
+            symbol=new_symbols,
+        )
+
+
+@canvas.events.key_press.connect
+def on_key_press(event):
+    global colors
+    if event.key == 'p':
+        # toggle face picking view
+        picking_filter.enabled = not picking_filter.enabled
+        markers.update_gl_state(blend=not picking_filter.enabled)
+        markers.update()
+    if event.key == 'r':
+        # reset marker symbols
+        colors = _colors.copy()
+        markers.set_data(
+            pos=pos,
+            edge_color=EDGE_COLOR,
+            face_color=colors,
+            size=MARKER_SIZE,
+            edge_width=EDGE_WDITH,
+        )
+
+
+canvas.show()
+
+
+if __name__ == "__main__":
+    print(__doc__)
+    app.run()

vispy/visuals/filters/__init__.py

@@ -2,8 +2,9 @@
 # Copyright (c) Vispy Development Team. All Rights Reserved.
 # Distributed under the (new) BSD License. See LICENSE.txt for more info.
 
-from .base_filter import Filter  # noqa
+from .base_filter import Filter, PrimitivePickingFilter  # noqa
 from .clipper import Clipper  # noqa
 from .color import Alpha, ColorFilter, IsolineFilter, ZColormapFilter  # noqa
 from .picking import PickingFilter  # noqa
-from .mesh import TextureFilter, ShadingFilter, InstancedShadingFilter, WireframeFilter  # noqa
+from .markers import MarkerPickingFilter  # noqa
+from .mesh import TextureFilter, ShadingFilter, InstancedShadingFilter, WireframeFilter, FacePickingFilter  # noqa