sdl_fungeoid

Fungeoid (Befunge-like) game for GNU/Linux and Android

Made it because I wanted to learn C and SDL. I also had to write a bit of platform-dependent code to create the file chooser dialogs: for Android I made a simple Activity using Java and for GNU/Linux I'm using a GTK3 file chooser dialog.

Fungeoids are a family of similar programming languages, the most popular is Befunge93. These languages are not useful, instead they are slightly fun.

The interesting thing is that the language is:

Two dimensional, there is a grid of instructions, each one represented by a letter.
The Program Counter (PC) is a pointer to the current instruction that moves up, down, left or right.
The memory is the grid itself because you can read and write to it, self-modifying code is possible.
The language is really difficult to compile.
See the Befunge93 documentation.

There are a lot of Befunge93 interpreters around but writing Befunge93 on a text editor is very cumbersome, sdl_fungeoid tries to be easy to use especially on Android.

I added some instructions to Befunge93 to make the language more fun, so you can choose between two languages:

Befunge93: The most popular one.
VeryFunge93: Befunge93 plus some instructions.

The best alternative I found is jsFunge IDE.

Development

Code overview

Check the first comment on every header file.

Input handling:
- I make no distintion between touch and mouse events.
- screens.c handles window and quit events, then, calls input_handle_event() so the input handles the touch/mouse/keyboard events.
- input_handle_event() returns an Input struct, screens.c passes the struct to the keyboard
- If the keyboard returns KEYB_EVENT_NOT_HANDLED then main.c should pass the input to the element below, e.g. the HUD.
- If the HUD does not handle the input then the input is passed to the keyboard, field, etc.

Code style

I'm learning C, I have to remember to:

Return zero on success and one on error.
Set variables to some value on declaration, pointers to NULL.
Set pointers to NULL when freeing memory.
Use static for global variables and private functions.
Can't define global variables on header files, see COLOR_XX for example.
Cannot do circular imports.
Private members of structs start with _.
For every struct with a constructor:
- Create a constructor structname_create() function that returns NULL on error. Remember to free the memory allocated inside the constructor on error.
- Create a destructor function structname_free() that returns void, do not check for NULL pointer because free() can handle NULL pointers, but if the struct has pointers inside I have to free them after checking for a NULL pointer.

Things to do

Use int8_t for cells or bigger
Fix that the game looks fullscreen on Android and is drawn below the notification bar.
Fix that while the load file GTK dialog is open, the game is frozen and inputs are buffered until the dialog is closed, where they are received together at the same time.
Add delete button to Android file chooser.
Add import button.
Implement function to select and delete an area of the field.
Draw on the field the possible code paths, looking at arrows and conditionals.
In the run screen, add possibility to clear the stack and to change the pointer direction.
Autosave once in a while.

SDL Notes

I'm just copying and pasting the SDL sources into this repo so the Android build works. I should update them manually.

Also I had to do modifications to Android.mk on SDL_image:

Change to SUPPORT_WEBP ?= false.
Delete IMG_WIC.c \

SDL and Android notes

The Android part of this game is quite hacky and horrible. I have no experience on Android, JNI and Java in general.

I wanted a file chooser so you can open and save files, looks like SDL is not designed for my use case.

How I'm doing it:

When the "open" or "save as" button is pressed, my code on C calls some function on os.h.
The functions I've written on os.c are based on source code from SDL, I think I got it from Android_JNI_GetClipboardText() located on SDL_android.h.
On the Java side I did extend SDLActivity as explained on SDL's README-android.md. So my main Activity is on SDLFungeoid.java.
So from os.c I call a function on SDLFungeoid.java. From there everything is standard Android code: Via an Intent I open another Activity where the user selects a file and that filename goes back to my SdlFungeoid activity via a Result.
Now I don't know how to give the filename to my C code, but I was lucky because I found that SDL has an event called SDL_DropEvent meant to support drag-and-drop. So from Java I just call the function onNativeDropFile(String) located on SDLActivity.java, then SDL sends the SDL_DropEvent to my C code and I get the filename there. As far SDL is concerned, it's like someone dragged and dropped a file.
That works OK when I we are opening files. The "save as" file chooser dialog should return the filename where we should save the file. To return the filename I do the same: I return a string from the Java code via a SDL_DropEvent but then the C code can't differentiate if the filename should be used to open a file or to save to it. So the Java code sends open:/home/.../filename.bf or `saveas:/home/.../filename.bf' as filenames.
Finally on C I just capture the event, check the prefix and load/save to the file.

GNU/Linux notes

For the file chooser dialog I'm using GTK+3.

GNU/Linux dependencies

sudo apt install build-essential libsdl2-dev libsdl2-image-dev libsdl2-ttf-dev libgtk-3-dev

Android compilation

I refuse to use Android Studio, so I do it manually.

sudo apt install openjdk-8-jdk ant android-sdk-platform-tools-common

As openjdk-8-jdk is not available on Debian Buster I downloaded the SDK manually from Oracle and put in a folder. This is why from now on I set the JAVA_HOME variable on each command. Not sure if I need this old java version, but the SDL guides say to use Java 8.

Then download the Android commandlinetools-linux (previously called sdk-tools-linux). This has to be placed inside a folder named sdk and the contents of cmdline-tools have to be put in a folder named latest (if not, an error will remind you). In the end you should have the sdkmanager in this path: .../sdk/cmdline-tools/latest/bin/sdkmanager. Do not download the SDK manually, we will use the SDK Manager for that.

With that done, accept the licenses. Pay attention to the paths in the command:

env JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" /home/mbernardi/extra/async/android/sdk/cmdline-tools/latest/bin/sdkmanager --licenses

Install build tools, SDK and NDK for the target version. Once I had to use --no_https:

env JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" /home/mbernardi/extra/async/android/sdk/cmdline-tools/latest/bin/sdkmanager --install "build-tools;26.0.0" "platforms;android-26"
env JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" /home/mbernardi/extra/async/android/sdk/cmdline-tools/latest/bin/sdkmanager --install "ndk-bundle"

Compiling:

cd ./android
env PATH="/home/mbernardi/extra/async/android/platform-tools/:$PATH" ANDROID_HOME="/home/mbernardi/extra/async/android/sdk/cmdline-tools/latest/bin/" JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" ./gradlew installDebug

If it gives license errors, maybe the ANDROID_HOME is wrong.

It gave me an error about mising platform folder in ndk. I installed an older version according to this:

env JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" /home/mbernardi/extra/async/android/sdk/cmdline-tools/latest/bin/sdkmanager --install "ndk;20.0.5594570"

And in this case compile with:

env ANDROID_HOME="/home/mbernardi/extra/async/android/sdk/" ANDROID_NDK_HOME="/home/mbernardi/extra/async/android/sdk/ndk/20.0.5594570/" JAVA_HOME="/home/mbernardi/extra/async/android/jdk1.8.0_301/" ./gradlew installDebug

Acknowledgments

Font:

Inconsolata
Copyright (c) 2011, Raph Levien (firstname.lastname@gmail.com), Copyright (c) 2012, Cyreal (cyreal.org)

SDL: has zlib license.

References

SDL tutorials

Other

#####  Color Palette by Paletton.com
#####  Palette URL: http://paletton.com/#uid=33t0E0kn9qlv8J4rfvFjlludJfm


*** Primary color:

   shade 0 = #2A6585 = rgb( 42,101,133) = rgba( 42,101,133,1) = rgb0(0.165,0.396,0.522)
   shade 1 = #1089CB = rgb( 16,137,203) = rgba( 16,137,203,1) = rgb0(0.063,0.537,0.796)
   shade 2 = #1F73A0 = rgb( 31,115,160) = rgba( 31,115,160,1) = rgb0(0.122,0.451,0.627)
   shade 3 = #2E576D = rgb( 46, 87,109) = rgba( 46, 87,109,1) = rgb0(0.18,0.341,0.427)
   shade 4 = #2E434E = rgb( 46, 67, 78) = rgba( 46, 67, 78,1) = rgb0(0.18,0.263,0.306) // Background

   #677278 // Lines

*** Secondary color (1):

   shade 0 = #D2B23A = rgb(210,178, 58) = rgba(210,178, 58,1) = rgb0(0.824,0.698,0.227)
   shade 1 = #FFCB07 = rgb(255,203,  7) = rgba(255,203,  7,1) = rgb0(1,0.796,0.027)
   shade 2 = #FCD025 = rgb(252,208, 37) = rgba(252,208, 37,1) = rgb0(0.988,0.816,0.145)
   shade 3 = #AB9644 = rgb(171,150, 68) = rgba(171,150, 68,1) = rgb0(0.671,0.588,0.267) // Select_1
   shade 4 = #7A6F46 = rgb(122,111, 70) = rgba(122,111, 70,1) = rgb0(0.478,0.435,0.275)

*** Secondary color (2):

   shade 0 = #D23A3A = rgb(210, 58, 58) = rgba(210, 58, 58,1) = rgb0(0.824,0.227,0.227)
   shade 1 = #FF0707 = rgb(255,  7,  7) = rgba(255,  7,  7,1) = rgb0(1,0.027,0.027)
   shade 2 = #FC2525 = rgb(252, 37, 37) = rgba(252, 37, 37,1) = rgb0(0.988,0.145,0.145)
   shade 3 = #AB4444 = rgb(171, 68, 68) = rgba(171, 68, 68,1) = rgb0(0.671,0.267,0.267) // Select_2
   shade 4 = #7A4646 = rgb(122, 70, 70) = rgba(122, 70, 70,1) = rgb0(0.478,0.275,0.275)


#####  Generated by Paletton.com (c) 2002-2014

Fungeoid commands

Movements
---------

SPACE:

RIGHT: >
LEFT: <
DOWN: v
UP: ^

RND: ? (93) x (fish)
BRIDGE: # (93) ! (fish)
STOP: @ (93) ; (fish)

Operators
---------

ADD: +
SUB: -
MUL: *
INTDIV: / (93)
// FLTDIV: , (fish)
MOD: %
NOT: ! (93)
GT: ` (93) ( (fish)

Stack
-----

DUP: :
SWP: \ (93) $ (fish)
POP: $ (93) ~ (fish)

Conditional movements
---------------------

HIF: _ (93)
VIF: | (93)
STR: " (93) " (fish) ' (fish)
ITER: k (98)

Input
-----

0: 0
1: 1
...
9: 9
A: a
B: b
...
F: f
INTIN: & (93)
CHARIN: ~ (93)

Output
------

INTOUT: . (93) n (fish)
CHAROUT: , (93) o (fish)

Write and get from world
------------------------

GET g
PUT p
FETCH: ' (98)
STORE: s (98)

Keyboard

Values (values):

9 8 7 a b c
6 5 4 d e f
3 2 1
  0

Movement and IO (movio):

< v ^ > # ? @ "
& ~ . , g p ' s

Operations and conditionals (oper):

+ - * / % ! `
: \ $ _ | " k

martinber/sdl_fungeoid