From 54dc0e897657cbe585ce02a27c4f2142f2e063c2 Mon Sep 17 00:00:00 2001
From: march3 <gang.wei@qq.com>
Date: Wed, 21 Jun 2023 21:05:57 +0800
Subject: [PATCH] =?UTF-8?q?Python=E8=B6=85=E4=BA=BA-=E5=AE=87=E5=AE=99?=
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---
 sim_scenes/fiction/earth_orbit_stopped.py | 81 +++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 sim_scenes/fiction/earth_orbit_stopped.py

diff --git a/sim_scenes/fiction/earth_orbit_stopped.py b/sim_scenes/fiction/earth_orbit_stopped.py
new file mode 100644
index 0000000..c4d3076
--- /dev/null
+++ b/sim_scenes/fiction/earth_orbit_stopped.py
@@ -0,0 +1,81 @@
+# -*- coding:utf-8 -*-
+# title           :如果地球停止公转
+# description     :如果地球停止公转，那它需要多久才会掉进太阳？ 大约65天
+# author          :Python超人
+# date            :2023-06-21
+# link            :https://gitcode.net/pythoncr/
+# python_version  :3.8
+# ==============================================================================
+from bodies import Sun, Earth, Moon
+from common.consts import SECONDS_PER_HOUR, SECONDS_PER_HALF_DAY, SECONDS_PER_DAY, SECONDS_PER_WEEK, SECONDS_PER_MONTH
+from sim_scenes.func import mayavi_run, ursina_run, camera_look_at, two_bodies_colliding, set_camera_parent
+from bodies.body import AU
+from simulators.ursina.entities.body_timer import BodyTimer
+from simulators.ursina.ui.control_ui import ControlUI
+from simulators.ursina.ursina_event import UrsinaEvent
+from ursina import application, camera, Vec3
+import math
+
+if __name__ == '__main__':
+    """
+    地球停止公转，多久到达太阳
+    地球如果停止公转，多久能掉入太阳？
+    https://www.zhihu.com/question/310815418
+    如果地球停止公转，那它需要多久才会掉进太阳？
+    https://www.guokr.com/article/440341
+    
+    """
+    # 地球的Y方向初始速度
+    EARTH_INIT_VELOCITY = 0  # 0km/s
+    sun = Sun(init_position=[AU/math.sqrt(2),0, AU/math.sqrt(2)], size_scale=1)
+    sun = Sun(init_position=[0, 0, AU], size_scale=1)
+    earth = Earth(init_position=[0, 0, 0],
+                  init_velocity=[0, EARTH_INIT_VELOCITY, 0],
+                  size_scale=1).set_light_disable(True)
+    bodies = [
+        sun,
+        earth
+    ]
+
+
+    def on_ready():
+        # 运行前触发
+        application.time_scale = 0.01
+        camera.fov = 50
+
+
+    def on_timer_changed(time_data):
+
+        if time_data.total_days < 18:
+            fov_offset = 0.1
+        elif time_data.total_days < 30:
+            fov_offset = 0.04
+        elif time_data.total_days < 40:
+            fov_offset = 0.02
+        else:
+            fov_offset = 0
+
+        if time_data.total_minutes % 3 == 0 and camera.fov > 1.5:
+            camera.fov -= fov_offset
+        camera_look_at(earth,rotation_z=0)
+
+        if two_bodies_colliding(sun, earth):
+            ControlUI.current_ui.show_message("地球已到达太阳表面", close_time=-1)
+            application.pause()
+
+    # 设置计时器的最小时间单位为分钟
+    BodyTimer().min_unit = BodyTimer.MIN_UNIT_HOURS
+
+    # 运行前会触发 on_ready
+    UrsinaEvent.on_ready_subscription(on_ready)
+    # 订阅事件后，上面的函数功能才会起作用
+    # 运行中，每时每刻都会触发 on_timer_changed
+    UrsinaEvent.on_timer_changed_subscription(on_timer_changed)
+
+    # 使用 ursina 查看的运行效果
+    # 常用快捷键： P：运行和暂停  O：重新开始  I：显示天体轨迹
+    # position = 左-右+、上+下-、前+后-
+    # position=(0, 0, 0) 的位置是站在地球视角，可以观看月相变化的过程
+    ursina_run(bodies, SECONDS_PER_DAY, position=(0, 0.002 * AU, -0.002 * AU),
+               show_timer=True,
+               show_grid=True)
-- 
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