Read mouse movement

Author: eulertour

example_scenes/opengl.py

@@ -8,6 +8,14 @@
 # Lines that do not yet work with the Community Version are commented.
 
 
+class Test(Scene):
+    def construct(self):
+        square = OpenGLSquare()
+        square.add_updater(lambda s: s.move_to(self.mouse_point))
+        self.add(square)
+        self.wait(60)
+
+
 class InteractiveDevelopment(Scene):
     def construct(self):
         circle = OpenGLCircle()

manim/renderer/opengl_renderer.py

@@ -189,7 +189,7 @@ def __init__(self):
         self.camera = OpenGLCamera()
 
         if config["preview"]:
-            self.window = Window()
+            self.window = Window(self)
             self.context = self.window.ctx
             self.frame_buffer_object = self.context.detect_framebuffer()
         else:
@@ -352,6 +352,7 @@ def init_scene(self, scene):
             self,
             scene.__class__.__name__,
         )
+        self.scene = scene
 
     def play(self, scene, *args, **kwargs):
         if len(args) == 0:
@@ -429,3 +430,15 @@ def get_raw_frame_buffer_object_data(self, dtype="f1"):
             dtype=dtype,
         )
         return ret
+
+    # Returns offset from the bottom left corner in pixels.
+    def pixel_coords_to_space_coords(self, px, py, relative=False):
+        pw, ph = config["pixel_width"], config["pixel_height"]
+        fw, fh = config["frame_width"], config["frame_height"]
+        fc = self.camera.get_center()
+        if relative:
+            return 2 * np.array([px / pw, py / ph, 0])
+        else:
+            # Only scale wrt one axis
+            scale = fh / ph
+            return fc + scale * np.array([(px - pw / 2), (py - ph / 2), 0])

manim/renderer/opengl_renderer_window.py

@@ -11,7 +11,7 @@ class Window(PygletWindow):
     vsync = True
     cursor = True
 
-    def __init__(self, size=None, **kwargs):
+    def __init__(self, renderer, size=None, **kwargs):
         if size is None:
             size = (config["pixel_width"], config["pixel_height"])
         super().__init__(size=size)
@@ -20,10 +20,18 @@ def __init__(self, size=None, **kwargs):
 
         self.title = "Title goes here"
         self.size = size
+        self.renderer = renderer
 
         mglw.activate_context(window=self)
         self.timer = Timer()
         self.config = mglw.WindowConfig(ctx=self.ctx, wnd=self, timer=self.timer)
         self.timer.start()
 
         self.swap_buffers()
+
+    # Delegate event handling to scene
+    def on_mouse_motion(self, x, y, dx, dy):
+        super().on_mouse_motion(x, y, dx, dy)
+        point = self.renderer.pixel_coords_to_space_coords(x, y)
+        d_point = self.renderer.pixel_coords_to_space_coords(dx, dy, relative=True)
+        self.renderer.scene.on_mouse_motion(point, d_point)

manim/scene/scene.py

@@ -22,6 +22,7 @@
 from ..constants import *
 from ..container import Container
 from ..mobject.mobject import Mobject, _AnimationBuilder
+from ..mobject.opengl_mobject import OpenGLPoint
 from ..utils.iterables import list_update, list_difference_update
 from ..utils.family import extract_mobject_family_members
 from ..renderer.cairo_renderer import CairoRenderer
@@ -81,6 +82,11 @@ def __init__(
         self.duration = None
         self.last_t = None
 
+        if config["use_opengl_renderer"]:
+            # Items associated with interaction
+            self.mouse_point = OpenGLPoint()
+            self.mouse_drag_point = OpenGLPoint()
+
         if renderer is None:
             self.renderer = CairoRenderer(
                 camera_class=self.camera_class,
@@ -950,3 +956,6 @@ def add_sound(self, sound_file, time_offset=0, gain=None, **kwargs):
             return
         time = self.renderer.time + time_offset
         self.renderer.file_writer.add_sound(sound_file, time, gain, **kwargs)
+
+    def on_mouse_motion(self, point, d_point):
+        self.mouse_point.move_to(point)