From 9a9cc8bdacb7541b7cd4a52ad705abc21f3e27fe Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Thu, 13 Jan 2022 20:29:58 -0800
Subject: [PATCH] Add presenter mode to scenes with -p option

---
 manimlib/config.py        |  7 +++++++
 manimlib/extract_scene.py |  1 +
 manimlib/scene/scene.py   | 29 +++++++++++++++++++----------
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/manimlib/config.py b/manimlib/config.py
index fef3d409..6dc65941 100644
--- a/manimlib/config.py
+++ b/manimlib/config.py
@@ -65,6 +65,12 @@ def parse_cli():
             action="store_true",
             help="Show window in full screen",
         )
+        parser.add_argument(
+            "-p", "--presenter_mode",
+            action="store_true",
+            help="scene will stay paused during wait calls until "
+                 "space bar or right arrow is hit, like a slide show"
+        )
         parser.add_argument(
             "-g", "--save_pngs",
             action="store_true",
@@ -306,6 +312,7 @@ def get_configuration(args):
         "start_at_animation_number": args.start_at_animation_number,
         "end_at_animation_number": None,
         "preview": not write_file,
+        "presenter_mode": args.presenter_mode,
         "leave_progress_bars": args.leave_progress_bars,
     }
 
diff --git a/manimlib/extract_scene.py b/manimlib/extract_scene.py
index f6bbd0b9..abec96ec 100644
--- a/manimlib/extract_scene.py
+++ b/manimlib/extract_scene.py
@@ -64,6 +64,7 @@ def get_scene_config(config):
             "end_at_animation_number",
             "leave_progress_bars",
             "preview",
+            "presenter_mode",
         ]
     ])
 
diff --git a/manimlib/scene/scene.py b/manimlib/scene/scene.py
index c67d2850..d52894b5 100644
--- a/manimlib/scene/scene.py
+++ b/manimlib/scene/scene.py
@@ -36,6 +36,7 @@ class Scene(object):
         "end_at_animation_number": None,
         "leave_progress_bars": False,
         "preview": True,
+        "presenter_mode": False,
         "linger_after_completion": True,
     }
 
@@ -62,6 +63,7 @@ class Scene(object):
         # Items associated with interaction
         self.mouse_point = Point()
         self.mouse_drag_point = Point()
+        self.hold_on_wait = not self.presenter_mode
 
         # Much nicer to work with deterministic scenes
         if self.random_seed is not None:
@@ -485,16 +487,21 @@ class Scene(object):
     def wait(self, duration=DEFAULT_WAIT_TIME, stop_condition=None):
         self.update_mobjects(dt=0)  # Any problems with this?
         self.lock_static_mobject_data()
-        time_progression = self.get_wait_time_progression(duration, stop_condition)
-        last_t = 0
-        for t in time_progression:
-            dt = t - last_t
-            last_t = t
-            self.update_frame(dt)
-            self.emit_frame()
-            if stop_condition is not None and stop_condition():
-                time_progression.close()
-                break
+        if self.presenter_mode and not self.skip_animations:
+            while self.hold_on_wait:
+                self.update_frame(dt=1 / self.camera.frame_rate)
+            self.hold_on_wait = True
+        else:
+            time_progression = self.get_wait_time_progression(duration, stop_condition)
+            last_t = 0
+            for t in time_progression:
+                dt = t - last_t
+                last_t = t
+                self.update_frame(dt)
+                self.emit_frame()
+                if stop_condition is not None and stop_condition():
+                    time_progression.close()
+                    break
         self.unlock_mobject_data()
         return self
 
@@ -615,6 +622,8 @@ class Scene(object):
             self.camera.frame.to_default_state()
         elif char == "q":
             self.quit_interaction = True
+        elif char == " ":
+            self.hold_on_wait = False
 
     def on_resize(self, width: int, height: int):
         self.camera.reset_pixel_shape(width, height)