snipe is a visual novel engine based on OpenGL and C++.
you can check out the demo project on release page.
please check that you've selected x86 as a target platform before you build on Visual Studio.

• features
• thirdparty libraries
• build environment
• simplified class diagram
• getting started
• using snipe as a 2D OpenGL engine
• information
• todo

• printing dialogues

• showing standing image

• playing audio

• showing choice menu

• save & load system

• save & load persistent data

• built-in UI system

• custom interpreted script engine

• screen language interpreter

• GLFW -  zlib license - for creating window and handle inputs

• GLAD - MIT license - for loading OpenGL functions

• glm - MIT license - for using matrix operation

• freetype - FreeType license - for loading font files and rasterizing it

• stb - MIT license - for loading & writing image files

• miniaudio - MIT-0 license - for playing audio files

• Compiler : Visual Studio 2022 ISO C++ 17 Standard (MSVC 2022 17.7)

• OS : Windows 11

to get started, you should assert that you have following files in a same folder : snipe.exe, script.txt, screen.txt. (game folder is optional, you can create any folder in root directory and access to it by writing res:\ in file path : res:\game\audio\song.mp3)

.
├── snipe.exe     *
├── screen.txt    *
├── script.txt    *
└── game/
    ├── audio/
    |   └── song.mp3
    ├── image/
    ├── background/
    ├── ui/
    ├── font/
    └── script/

step 1. write following text to screen.txt :

(if you get error messages while loading fonts, use your custom font file path instead of "C:\Windows\Fonts\arial.ttf".)

new "root"
    def "window_title"                = "\"Untitled\""
    def "current_scene"               = "main"
    new "scene"
        def "name"                    = "main"
        def "current_camera"          = "cam"
        def "current_dialog"          = "dialog"
        def "current_choicebox"       = "choice"
        new "camera"
            def "name"                = "cam"
        new "dialog"
            def "name"                = "dialog"
            def "font_color"          = vec4(1, 1, 1, 1)
            def "font_path"           = "C:\Windows\Fonts\arial.ttf"
            def "font_size"           = 32
            def "position"            = vec2(360, 720)
            def "size"                = vec2(900, 200)
            def "namelabel_position"  = vec2(360, 650)
            def "namelabel_font_path" = "C:\Windows\Fonts\arial.ttf"
        new "choicebox"
            def "name"                = "choice"
            def "font_path"           = "C:\Windows\Fonts\arial.ttf"
            def "font_size"           = 32
            def "position"            = vec2(500, 300)
            def "size"                = vec2(600, 200)
            def "each_box_size"       = 50.0

step 2. write following text to script.txt :

# define characters.
# first parameter means charcter's name.
# second one means character's namebox color.
char a "a" vec4(0.96, 0.478, 0.54, 1)
char b "b" vec4(0.529, 0.8, 1, 1)

# define string variables called "player" and "hello".
# variable "player" has a value of "b".
# you can receive string input from player by using "input" keyword.
string player "b", hello "world"

# define label called "start".
# unlike Ren'Py, you should call / jump to "start" label on global scope by yourself.
label start
    # a will say "Nice to see you, b".
    # you can access to variable using ["variable name"] in a string.
    a "Nice to see you, [player]."

    # show the choice menu.
    choice
        # if you want some character to say something as the choice event starts,
        # write it once in the choice keyword's scope.
        b "What should I say?"

        # you can add choices by using "case" keyword.
        # when the choice event is finished, interpreter will execute the following lines of "case" keyword.
        case "Me too! It's been a while."
            jump "good_ending"
        case "Who are you?"
            jump "bad_ending"

label good_ending
    "good ending."

label bad_ending
    "bad ending."

# jump to label called "start".
jump_main "start"

step 3. now run snipe.exe. to get more information, please read HOW_TO_USE.md.

you can use snipe as a 2D OpenGL engine - please modify main.cpp like following code.

/* main.cpp */
#include "main.h"

Root* root;

int main() {
    // if you don't use multi-threading things, you should set this variable false
    SNIPE_USING_MULTITHREAD = false;
    // to set attributes about creating window, change the variables of root before initialize it.
    root->WINDOW_WIDTH = 1600;
    root->WINDOW_HEIGHT = 900;
    root->init();
    /*
    // your initializing code here...
    // you can make your own class that inherits Object2D and add to scene.
    // intializing code looks like this - 

    Scene2D* myScene = root->addScene2D(L"myScene");
    root->currentScene = myScene;
    Camera2D* myCamera = myScene->addCamera2D(L"myCamera");
    myScene->makeCameraCurrent(myCamera);

    // you should define add[class name] function
    // to Scene2D class before using this
    myScene->addMyClass(L"myClass"); 
    */
    while (not glfwWindowShouldClose(root->window)) {
        root->process_frame();
    }
    root->quit();
    return 0;
}

to use Dialog and ChoiceBox class on C++, use it like following code :

/* myClass.cpp */
static int choiceResult = -1;
static void test(Root* root) {
    Dialog* myDialog = root->currentScene->getObject(L"Dialog", L"myDialog");
    ChoiceBox* myChoiceBox = root->currentScene->getObject(L"ChoiceBox", L"myChoiceBox");

    // to say something :
    myDialog->say(L"myName", L"Hello World");

    // to show the choice menu :
    myChoiceBox->choice({L"1", L"2", L"3"}, &choiceResult);
}

void myClass::update() {
    FrameEvent event = owner->root->currentFrameEvent;
    if (choiceResult != -1){
        std::cout << "selected index: " << choiceResult << "\n";
        choiceResult = -1;
    }
    if (event.justKeys[GLFW_KEY_SPACE].action == GLFW_PRESS){
        test(owner->root);
    }
}

• this project will run only on Windows.

• i did not apply many encapsulations because my ultimate goal was control engine through the custom script, not in C++. In addition, i hate to write many set / get functions.

• there are some unsolved problems(i'll try to fix it) :

  • slider class does not work well when zoom in / out or rotate the camera.
  • textedit class supports only 1 line that can be inputted.
  • camera2d class's offset works a little bit weird when window being set to full size.
  • you cannot input space(' ') when cursor position of textedit class is zero.

• the source of GLFW has been modified for Windows build.

• i did not write code in Modern-OpenGL style because i had a problem with shader overlapping. furthermore, you can save many of GPU memories by not creating VBO & VAOs and shader.

• like python, you have to use 4 spaces instead of 1 tab when creating new scope in script.

• if there's non-english characters in executable's path, it won't work.

• this engine uses multi-thread. so there's should be undiscovered problems about that.

• you cannot use numbers in variable / object's name.

• compress all the image files using stb_image and convert it to 1 file using zlib.
• create pixelate shader.
• implement array operator([ ])

2023-08-18 ~
MIT Licensed.