Lemon-JS

An accessible rendering engine in Javascript.

Note: The goal of this project is to stay simple to make people understand and experiment with 3D rendering

Demonstrations

• A simple cube
• Billboard sprites
• A 3D model
• Scene management
• Lights
• Make blob using shaders
• Post processing stack
• Using a Skybox
• Use video as a texture
• Hide out of screens objects
• Using Materials

Features

• Access to the low level API
• Rendering queues and commands system
• Lights support
• Shaders
• Scene management (nodes, hierrachy, …)
• Separated "engine" logic from the low level part
• Post processing
• Loading models, sprites, videos and custom mesh

Todo

• Fonts support
• Advanced lighting
• Batching

Installation

• Download the latest version of LemonJS or install it with npm install @dono/lemon-js
• Copy "shaders" folder to your project to get default shaders
• Enjoy!

The Hello world of 3D : A cube

import {
  ProgramLibrary,
  RenderCanvas,
  Camera,
  Mesh,
  Scene,
  PointLight,
  Geometry,
  Material,
  Color
} from "@dono/lemon-js";

// Use the ProgramLibrary helper to build a shader with lights and texture support
ProgramLibrary.loadFromFile('DefaultShader', './shaders/GLSL/default.vert', './shaders/GLSL/default.frag', ['USE_LIGHT', 'USE_TEXTURE']);

// Create a new renderer using HTML identifier
const renderer = new RenderCanvas("simulation");

// A camera to draw the scene
const camera = new Camera();
camera.move(3, 3, 3);
camera.setViewport(0, 0, renderer.getWidth(), renderer.getHeight());

// Create a scene where we can add sprites, lights, objects, …
const scene = new Scene();

// Now we can create our first cube
const cube = new Mesh(
    Geometry.createCube(0.5, 0.5, 0.5),
    Material.Create('default'),
    ProgramLibrary.get('DefaultShader'),
);
scene.add(cube);

// A light to see something
const light = new PointLight();
light.setPosition(0, 3, 0);
scene.add(light);

let previous = 0;
let deltatime = 0;
const applicationLoop = (timestamp) => {
    requestAnimationFrame(applicationLoop);

    // Calculate elapsed time between two frames
    deltatime = timestamp - previous;
    previous = timestamp;

    // Update scene …
    scene.update(deltatime);

    // … then draw it!
    renderer.clear(new Color(30, 30, 30));
    renderer.render(scene, camera);
    renderer.display();
};
requestAnimationFrame(applicationLoop);

The result can be found here.

How to contribute

• Clone this repository
• npm install from the folder
• npm run dev (developement) or npm run build (production)
• Enjoy!

License

MIT