Module gemini_engine::elements

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Expand description

Gemini’s core elements module. This and the view module make up Gemini’s core rendering pipeline.

Quick Start

Let’s get started with a simple program to demonstrate how Gemini works:

use gemini_engine::elements::{Point, Vec2D, view::{View, ColChar, Wrapping}};
use gemini_engine::gameloop;

const FPS: f32 = 30.0;

fn main() {
    let mut view = View::new(40, 8, ColChar::BACKGROUND);
    let mut point = Point::new(Vec2D::new(10,5), ColChar::SOLID);

    loop {
        view.clear();

        point.pos.x += 1;

        view.blit(&point, Wrapping::Wrap);
        view.display_render().unwrap();

        gameloop::sleep_fps(FPS, None);
    }
}

Ok, let’s go over this and see what’s going on. We start by creating a View and Point. the View takes two numbers for the width and height, as well as a ColChar. The Point takes a Vec2D and a ColChar.

We use ColChar to say exactly what each pixel should look like and what colour it should be. Here we used the built in ColChar::BACKGROUND and ColChar::SOLID to keep the code simple. You can read more in the ColChar documentation.

At its heart, Vec2D is just a pair of isize integers for defining things such as position, size and movement. We used it here to define the Point’s starting position, before the game loop.

Now that we’ve got initialisation out of the way, let’s get on to the juicy part: the main loop. In Gemini the main loop always goes as follows:

  1. Clear the View
  2. Work through any logic you might have (moving things around, taking inputs etc.)
  3. Blit all the ViewElements to the screen
  4. print the result of View.display_render
  5. Sleep

In our case, we want to move our Point one unit to the right every frame, so we increase its value by one here. Next we blit the Point to the View (adding it to the View’s internal canvas) and render. Rendering will display the view in the terminal (make sure your terminal is large enough to fit the whole image!). The last line of our code sleeps for 1/FPS seconds. We pass None in place of what would normally be a Some(Duration) type, displaying the amount of time it took to blit and render everything so that gameloop::sleep_fps can accomodate for the time taken to render. Since this example program is quite simple, we’ve just passed None. You can see how best to write a gameloop in the gameloop documentation.

There you have it! You’ve written your first program with Gemini! As of me writing this now it’s still very much a work in progress, so any feedback or issue requests would be appreciated :)

Re-exports

Modules

Structs

  • PixelContainer
    A PixelContainer only has a pixels property, which gets returned directly to the View during blit
  • VisibilityToggle
    VisibilityToggle is a container for a ViewElement with a property visible. When blit to the view the contained element will only appear if visible is true