From 9d60fad90149b4ac59d096bdc134011d9374477b Mon Sep 17 00:00:00 2001
From: jaysunxiao <jaysunxiao.gmail.com>
Date: Sun, 2 Jan 2022 19:22:59 +0800
Subject: [PATCH] doc

---
 doc/demo03_lifecycle/lifecycle.md | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/doc/demo03_lifecycle/lifecycle.md b/doc/demo03_lifecycle/lifecycle.md
index bbf8450..0f6d298 100644
--- a/doc/demo03_lifecycle/lifecycle.md
+++ b/doc/demo03_lifecycle/lifecycle.md
@@ -1,13 +1,38 @@
+# 1. 场景树
+
 ![Image text](image/scene-tree.png)
 ![Image text](image/场景循环.png)
+
+# 2. 帧率
+
+- 帧率 Framerate ，指画面每秒更新多少次 (FPS, Frames Per Second)
+
+```
+比如，
+  FPS = 50 , 即每 20ms 秒更新一次
+  FPS = 60,  约 16.7ms 秒更新一次
+
+通过代码可以设置，要求 godot 引擎尽量以此帧率运行 ，但实际帧率还是会有偏差
+Engine.target_fps = 120
+```
+
 ![Image text](image/场景帧.png)
+
+- delta time上一帧的间隔
+
+```
+匀速移动的优化：
+ var step = 0.8f * deltaTime;
+其中，
+   0.8f  表示每秒位移 0.8 单位
+```
+
 ![Image text](image/delta.png)
 ![Image text](image/delta-1.png)
 ![Image text](image/godot_process.jpg)
 ![Image text](image/godot_node.jpg)
 ![Image text](image/godot_lifecycle.jpg)
 
-
 ![Image text](image/process.png)
 ![Image text](image/process-1.png)
 ![Image text](image/physics.png)