🎨 JavaScript graphic library for retro CG
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README.md

gretro

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Gretro (grétrou, グレトロ) is a JavaScript graphic library for retro CG.

Features

  • 16 colors chosen from available 4096 colors
  • 16 default tile patterns and 16 custom tile patterns
  • drawing in pixels, no anti aliasing
  • plugin architecture for extending gretro.Canvas

Online Playground

Install

browser
$ bower install gretro
<script src="/path/to/gretro.js"></script>
node.js
% npm install gretro

Usage

var canvas = new gretro.Canvas(220, 110);

canvas
  .stroke(13).circle( 40, 40, 30)
  .stroke( 7).circle(110, 40, 30)
  .stroke(10).circle(180, 40, 30)
  .stroke(14).circle( 75, 70, 30)
  .stroke(12).circle(145, 70, 30);

Rendering

browser
var gretroCanvas = new gretro.Canvas(640, 400).draw(fn);

var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var imageData = context.createImageData(640, 400);

imageData.data.set(gretroCanvas.toRGBA());

context.putImageData(imageData, 0, 0);

draw directly to the html-canvas

var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var imageData = context.getImageData(0, 0, 640, 400);

new gretro.Canvas(640, 400, imageData.data).draw(fn);

context.putImageData(imageData, 0, 0);
node.js

use node-png npm install png

var Png = require("png").Png;
var fs  = require("fs");

var png = new Png(new Buffer(gretroCanvas.toRGB()), 640, 400, "rgb");
var png_image = png.encodeSync();

fs.writeFileSync("./image.png", png_image.toString("binary"), "binary");

API

Canvas

Constructor

  • new Canvas(width:int=640, height:int=400, buffer:Uint8Array=null) : Canvas

Instance methods

Environment
Setting
Color
Region
Shape
Image
Output
Utility

Color

You can use 16 colors on a canvas. It is possible to select from 4096 colors.

default color palette

customize color

canvas
  .setColor(0, 0x44dd77).setColor(1, 0x22aa88)
  .fill(1).rect(20, 20, 60, 60);

color generator

set a function that returns a calculated color number instead of a color number.

canvas
  .fill(function(x, y) {
    return 16 * Math.random();
  }).rect(20, 20, 60, 60);

Tile

A tile is a 4 x 4 dot pattern with 2 colors that is used to express gradation in generally.

usage

Set array that contains color1, color2 and tile-index instead of a color number.

canvas.fill([ color1, color2, tileIndex ]);

default tile palette

custom tile

TileIndex 16-31 are customizable.

canvas
  .setTile(16, 0x4a12)
  .stroke(13).fill([ 0, 13, 16 ])
  .circle(50, 50, 40, 40);
/* 1 2 4 8
   □ ■ □ □ = 2
   ■ □ □ □ = 1
   □ ■ □ ■ = a
   □ □ ■ □ = 4
            0x */

Plugins

gretro-text

plugin to draw a text

gretro-paint

plugin to paint a region

Contribution

  1. Fork (https://github.com/mohayonao/gretro/fork)
  2. Create a feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'add some feature')
  4. Run test suite with the gulp travis command and confirm that it passes
  5. Push to the branch (git push origin my-new-feature)
  6. Create new Pull Request

License

Gretro is available under the The MIT License.