Navigate to source location by writing code

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UE4 has a functionality of "Goto Definition",

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FSourceCodeNavigationImpl::NavigateToFunctionSource

which uses two apis from dbghelp.dll,

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SymGetSymFromName64
SymGetLineFromAddr64

Chrome memo

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To prevent inactive tab from using cpu resources, in address bar, visit

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chrome://discards

toggle restless pages 'Urgent Discard' to grey under 'Actions' column.

chrome://flags#

enable-parallel-downloading
enable-force-dark

refer to:
https://www.askvg.com/tip-enable-tab-freeze-or-tab-suspend-feature-in-google-chrome/
https://blog.csdn.net/ythuiyi/article/details/113506238

UE4 blueprint memo

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Level Viewport
	bp_test
		Details
			Actor
				Tags
	Box Trigger
		Actor Hidden in Game
 
 
Level Blueprint
	1
		DestroyActor
	Event Tick
		Get All Actors with Tag
			Get Actor Location
			Set Actor Location
	Add Event for Trigger Box 1
		OnActorBeginOverlap
			cast to ThirdPersonCharacter
				begin_event
		OnActorEndOverlap
 
bp_test: Event Graph
	Event BeginPlay
		Exec
			Sequence
				Delay
					Print String
				Set Timer by Event
					Event
						test_event
					Return Value
						Promote to variable
							New Var 1
			If
				New Var 0
					true
						Print String
					false
						Print String
	Event Destroyed
	4
		New Var 1
			Clear and Invalidate Timer by Handle
	5
		Array Var 2
			For Each Loop
			Reverse for Each Loop
	6
		Struct Var 3 : Struct Type 3
			Break Struct Type 3
	7
		Enum Var 4 : Enum Type 4
			Switch on Enum Type 4
	Add Timeline
		Lerp Vector
			Set World Location
 
	test_event: Custom Event
		Exec
			Draw Debug Point
ThirdPersonCharacter : Event Graph
	begin_event: Custom Event
	Event Dispatchers
		hitDemon
	1
		hitDemon
Demon1 : Event Graph
	Get Player Character
		cast to ThirdPersonCharacter
			bind event to hitDemon
				add custom event
Demon1
	Details
		Collision
			Collision Presets
				Custom...
ThirdPersonCharacter : Blueprint
	Components
		ThirdPersonCharacter
			Use Controller Rotation Yaw
		CameraBoom
			Use Pawn Control Rotation
		CharacterMovement
			Orient Rotation to Movement
	1
		Capsule Component
			Get Word Location as Start
			Get Forward Vector
				x 10000
					+ Get World Location
						as End
							Line Trace By Channel
Get Player Controller
	Show Mouse Cursor
	ConvertMouseLocationToWorldSpace
 
Level Blueprint
	Q
		CubeMesh
			Static Mesh Component
				Create Dynamic Material Instance
					Set Vector Parameter Value
						Parameter Name : cube_color4
 
Mat_cube asigned to CubeMesh
	cube_color4 : Constant3Vector
		Base Color

In Actor Blueprint, enable input event,

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bp_test: Event Graph
	Event BeginPlay
		Get Player Controller
			Enable Input

Questions,

  • Why can't 'Delay' function be used in 'While Loop'?
  • In Game mode, can't control previous character while incarnating into a new character?

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    ThirdPersonCharactor1
	Details
		Pawn
			Auto Possess Player
				Player 0

refer to:
我是一只好蛋YEAH
https://blog.csdn.net/sunday7279/article/details/88665577

Rendering mp4 video not silky, why?

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The original HD mp4 file 'movie.mp4' plays very smoothly. I picked out the h264 stream saved as 'movie.264' from it, then using mp4v2 converted 'movie.264' to a new mp4 file 'output.mp4'. However, experience of watching 'output.mp4' was very bad. Why?

I debugged the 'ClipTrack' function in 'mp4v2/test/OLD/mp4clip.cpp', found a key argument 'renderingOffset' of function 'MP4WriteSample'. All examples searched from the web about writing h264 to mp4 through mp4v2 set 'renderingOffset' to 0, while in 'ClipTrack', 'renderingOffset' of the function 'MP4WriteSample' is directly set to the value from 'renderingOffset' of the function 'MP4ReadSample'.

Here we make a concept clear, the 'sample' entity in mp4 file format specification is equal to a frame which can completely rendering as a picture. A sample consists of several nalus, a nalu whose start code is 0x00, 0x00, 0x00, 0x01 indicates a new sample, while a nalu which starts with 0x00, 0x00, 0x01 is among a sample, and a sample needs not to be a IDR key frame.

Through carrying 'renderingOffset' value at beginning of each sample in 'movie.264', I did generate an 'output.mp4' which displays as smoothly as the original one.

Did 'renderingOffset' mean time stamp of a sample? No, at least not exactly. By watching log, I found its value was not increasing as time went by.

I continued debugging mp4v2, then saw a key word 'ctts' atom, and searched a link from the web,

https://blog.csdn.net/cheyo809775692/article/details/100924523

I now understand, the decoding order of h264 samples is slightly different from the rendering order of them.

For example, in stts atom,

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'decoding order'	'sample count'		'sample duration'
1,2,3,4			4			20
5			1			40
6,7,8			3			20
9			1			60

in ctts atom,

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'decoding order'	'sample count'		'sample offset'
1,2,3			3			20
4			1			40
5			1			0
6			1			40
7			1			0
8			1			40
9			1			0

final rendering timing is

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'decoding order'	1	2	3	4	5	6	7	8	9
'duration'		20	20	20	20	40	20	20	20	60
'rending order'			1	2	3	5	5,4	7	6	9	9,8	9

Terms,

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mvhd: movie header
tkhd: track header
mdhd: media header
stsd: sample descriptions
stts: time to sample
ctts: composition offset
stss: sync sample offset
stsc: sample to chunk
stsz: sample size
stco/stco64: chunk offset
dts: decoding timestamp
pts: presentation timestamp

三国备忘录

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何进/此小儿之见也
董卓
	蔡邕
孙坚/为玉玺发誓赌咒
	祖茂
	孙策
		于吉
		许贡
吕布
	陈宫
	高顺/夏侯惇
	张辽
徐州城
	陈珪
	陈登
		车冑
刘安
刘备/孔北海乃复知天下有刘备邪?
曹老板
	于禁
	庞德
袁绍
	许攸/官渡/乌巢
	田丰
韩馥/疑袁绍追杀自已到张邈处而自杀
公孙瓒
	公孙越
司马懿
	张春华/杀婢女

expect scp

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auto_scp()
{
	local filepath=$1
	expect -c "
		set timeout 10
 
		spawn scp scp://someone@192.168.12.3:1234//home/someone/$filepath .
 
		expect \"password:\" 
		send \"toodangerous\r\"
 
		interact
	"
}

refer to:
https://blog.csdn.net/f_zyj/article/details/93475830
https://zhuanlan.zhihu.com/p/25164676

strdupa in Windows

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my_alloca.h

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#ifndef _MY_ALLOCA_H_
#define _MY_ALLOCA_H_
 
#include <malloc.h>
 
__declspec(thread) extern size_t strdupa_len;
__declspec(thread) extern char* strdupa_p;
#define strdupa(_str) \
( \
	strdupa_len = strlen(_str), \
	strdupa_p = (char*)_alloca(strdupa_len + 1), \
	memcpy(strdupa_p, _str, strdupa_len + 1), \
	strdupa_p \
)
 
#endif

my_alloca.c

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#include "my_alloca.h"
__declspec(thread) size_t strdupa_len;
__declspec(thread) char* strdupa_p;

example.c

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#include "my_alloca.h"
 
int main()
{
	char* p = strdupa("hi");
}

Select Windows SDK version when building using cmake

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Read cmake online doc carefully, https://cmake.org/cmake/help/latest/variable/CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION.html

So when we build project which has CMakeLists.txt, we can select Windows SDK version in this way:

  1. In explorer, navigate to like C:\Program Files (x86)\Windows Kits\10\Include.
  2. For cmake always finds the newest version to build our project, we can just rename all sdk versions which is newer than we want. e.g. if we want 10.0.19041.0 to build our project, but 10.0.22581.0 is newer, we rename 10.0.22581.0 to 10.0.0.22581.0, the rule is among tokens split by period signs, the third token number is the key word that cmake sorts them to get the largest as newest.
  3. Start cmake to configure the project, it will find the right sdk version.
  4. After cmake is done in configuration, rename 10.0.0.22581.0 back to 10.0.22581.0.

Open sourced games

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https://github.com/FreezingMoon/AncientBeast
https://github.com/CleverRaven/Cataclysm-DDA
https://gitee.com/GITLZ/PlantsVsZombies
https://github.com/jynew/jynew
https://github.com/BKcore/HexGL
https://github.com/freeciv/freeciv-web
https://github.com/wesnoth/wesnoth
https://github.com/opentomb/OpenTomb
https://github.com/Unvanquished/Unvanquished
https://github.com/amiruqdah/mario-party
https://github.com/stuntrally/stuntrally
https://github.com/lo-th/3d.city
https://github.com/Casmo/tower-defense
https://github.com/softvar/save-the-forest
Unity Gigaya
https://github.com/wuhaoyu1990/KingdomRush

refer to:
https://www.toutiao.com/article/7052673030098534951/