H2D-Introduction.md

Introduction

The code samples in the first pages in the H2D section are coded without any external resources allowing to just copy and paste the code and compiling it directly on your machine.

Let's recap now. The smallest code for a Heaps application is the following:

class Main extends hxd.App {
    static function main() {
        new Main();
    }
}

Of course all you get to see here is a black screen or window with no content. Thus to create content an instance of a class (an object) must be added that inherits from h2d.Object (to make 2D content).

Adding content

There are many classes to choose from that all inherit from h2d.Object (see the API). Therefore in the next sample we revisit the code of the [[Hello World]] sample and add a bitmap. Two objects now make up the content here: h2d.Text and h2d.Bitmap (and as said, both are h2d.Objects). The bitmap requires a tile (h2d.Tile) as graphical resource (which will be explained in a later section). Here we can generate the needed tile from code using fromColor(...).

By the way this is a first straight dive into the Heaps engine! All features used here will be explained in detail in the following sections!

Code

    class Main extends hxd.App {
        var bmp : h2d.Bitmap;
        override function init() {
            var tf = new h2d.Text(hxd.res.DefaultFont.get(), s2d);
            tf.text = "Hello World !";

            // allocate a Texture with red color and creates a 100x100 Tile from it
            var tile = h2d.Tile.fromColor(0xFF0000, 100, 100);
            // create a Bitmap object, which will display the tile
            // and will be added to our 2D scene (s2d)
            bmp = new h2d.Bitmap(tile, s2d);
            // modify the display position of the Bitmap sprite
            bmp.x = s2d.width * 0.5;
            bmp.y = s2d.height * 0.5;
        }
        // on each frame
        override function update(dt:Float) {
            // increment the display bitmap rotation by 0.1 radians
            bmp.rotation += 0.1;
        }
        static function main() {
            new Main();
        }
    }

With overriding hxd.App's update method Heaps allows us to define what should happen each frame. (dt stands for the number of milliseconds that have passed since the last time the update method has been called.) The underlying h2d.Object (from which h2d.Bitmap inherits) provides the bitmap with features to change its position and rotation.

Screenshot

The next section will discuss h2d.Object a bit closer.

And as said h2d.Tile which the bitmap required will be discussed in a later section: [[Graphical surfaces]].