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Motivations

In order of priority

  1. Graphics Programming
  2. Learning Embedded C/C++
  3. Programming the Vita/Switch
  4. Porting Experience

Note: I'm a web developer professionally, so besides my university C++ projects, I haven't used it much.

Random Notes

VITA Hardware

Type Model
CPU ARM Cortex-A9 MPCore (32-bit armv7-a, 4 cores) 2GHz (NEON SIMD)
RAM 512MB
GPU PowerVR SGX543MP4+ 128MB (4 cores)
DISPLAY 5" 960x544 (16:9) OLED multi-touch @ 220ppi
INPUT Dual Touch Pads, Motion, Compass, D-pad, 16 Buttons, 2 Analog Sticks

PSP in Comparison

Purposely not targeting PSP for legacy reasons. This is just for reference since the codebase was originally for PSP.

Type Model
CPU 20-333 MHz MIPS R4000x2
RAM 32MB-64MB
GPU RE+SE-90nm 2MB (133Mhz)
DISPLAY 4.3" 480x272 (16:9) LCD 24bit @ 220ppi
INPUT D-pad, 16 Buttons, 2 Analog Sticks

Switch Hardware

Type Model
CPU Quad-core Cortex-A57 + Quad-core Cortex-A53 @ 1.02 GHz
RAM 4GB LPDDR4
GPU Nvidia GM20B Maxwell-based GPU
DISPLAY 6.2-inch, 1280 × 720p LCD (237 ppi); Docked 1080p
INPUT 2 Wireless Joycons, Motion, Compass, D-pad, 16 Buttons, 2 Analog Sticks, Touchscreen

Directory Stucture

The original bookr had all it's source files outside in the root directory. I've tried to arrange them in folders so as not to get overwhelmed.

  data          - should have all images and external resources, should also subdivide into vita/psp
  ext           - external libraries used statically by bookr
  sce_sys       - vita resources, should refactor into data/vita
  src           - main directory for c++ source files
    filetypes   - classes for specific filetypes for books
    graphics    - has main rendering, texture classes and shaders (eventually)

Licensing and Copyright

When porting an open source project it's hard to know all the legal terms.
So bookr uses the GNU GPLv2+ which requires

  • Include Original (all in this repo)
  • Disclose Source (this repo)
  • Include Copyright (Included to original files, modified files also have my copyright; is this correct?)
  • State Changes (commits on this repo)
  • Include License (LICENSE in this repo)

So for the things I change I'm adding my copright and a notice of modification before the GPL notice. Please add an issue if I did anything wrong.
Some links

Macro definitions

#ifdef __vita__

Checking for preprocessor macro variables on your tool chain arm-vita-eabi-gcc -dM -E - < /dev/null | grep -i vita. That's how i found __vita__

Versioning Based on git tags

The cmake tutorial goes through setting up variables like version through an internal environment variables. See CMakeLists.txt.

Using Visual Studio Code

http://stackoverflow.com/questions/37522462/visual-studio-code-includepath link macos specific libs from /Frameworks.../ to /usr/local/include for intellisense.

ln -s /System/Library/Frameworks/OpenGL.framework/Headers/ /usr/local/include/OpenGL

Going from GLUT to GLFW

On macOS 10.9+ i get deprecation warnings for the system's GLUT, so swapping to GLFW (newer and more supported)

... 17 other warnings
src/graphics/fzscreenglut.cpp:183:2: warning: 'glutMainLoop' is deprecated: first deprecated in macOS 10.9
      [-Wdeprecated-declarations]
        glutMainLoop();
        ^
/usr/local/include/GLUT/glut.h:438:22: note: 'glutMainLoop' has been explicitly marked deprecated here
extern void APIENTRY glutMainLoop(void) OPENGL_DEPRECATED(10_0, 10_9);

NOTE: Now OpenGL is deprecated in favour of Metal on MacOS.

Data files on Platform

We use have user.xml to store configuration info. This will be in:

  • vita: ux0:data/Bookr
  • switch: ./ - The SD card is automatically mounted as the default device, usable with standard stdio. SD root dir is located at "/" (also "sdmc:/" but normally using the latter isn't needed). The default current-working-directory when using relative paths is normally the directory where your application is located on the SD card.
  • desktop: ./

C++17

The codebase is using more of the C subset than C++, maybe I can make it cleaner and learn the C++17 features too.

The versions on gcc/clang on platforms:

Platform Compiler Version
Switch GCC v10.1.0
Vita GCC v10.1.0
Mac Clang 12
Windows MSVC++

All of them have complete C++17 support, so targeting that.

Initalization

int val = 5; //copy init
int val(5);  //direct init
int val{5};  //uniform init <--- C++11

Double buffering

Two variables in ram; front and back buffer.
Front is the one shown to you on the screen; back is the only one you can draw to.
Swap them to show the new drawn one, but while loops seems to go so fast it read buttons twice.

General GUI/Game loops

So it seems like most applications share the same paradigm of

  • initalize display

  • while (not exiting app)

    • render/draw the "state" of the app (start draw, swap buffers, stop draw)
    • check user input
    • change state based on user input

  • deinitalize display

OpenGL

Looks like bookr used the old fixed-pipeline version of OpenGL which has been depricated.
Replacing it with a good programmable-pipeline abstraction feels hard.
Got a cool shader class so far.

MuPDF

The general idea seems to be to read the file and initalise some structures it has defined and finally draw a page into a pixmap buffer. Then put the pixmap into a texture onto the GPU which you can render.

SDL

I chose purposely to not use SDL so I could learn a low level graphics API. Funnily enough vita2d does somewhat abstract that, but the OpenGL on desktop and switch are what I wanted to learn, which really differs from the vita's graphics api (and the psp's).

It's obvious however that I would be releasing features faster if I were using SDL, as the abstractions would take care of platform specific issues. It sometimes feels as if I am writing the SDL library (albiet a bad imitation) from scratch. But the bigger picture and a desire I still have is a 3D visualisation; i.e. of a bookshelf or library.

I belive this is a difference between a file manager and an e-book reader. I want to take inspiration from this for vita/switch.

Bitwise Operations

  • "|=" - OR a |= b is a = a | b
  • "&=" - AND a &= b is a = a & b

Style

  1. Use spaces instead of tabs
  2. 2 Spaces for normal indentation

This will change to 4 spaces soon.

Cmake Special Flags

mkdir Release
cd Release
cmake -DCMAKE_BUILD_TYPE=Release .. # This adds -O3
make

same for Debug # Adds -DDEBUG

Old Class Hierarchy

main .
  bkdocument .
    
    bklayer .
      fzfont graphics
        fztexture graphics
          fzimage graphics
            fzrefcount graphics
            fzinputstream base
              fzrefcount base
      bkuser .
    
    bkbookmark .
      fzscreen graphics
        pspdebug - ifdef PSP
      pspiofilemgr - ifdef PSP else fcntl