tex-pack

This is a small extension that allows you to combine multiple images into texture pages at runtime through a bin packing algorithm.

Example (pre-2.3)

tpage = tex_page_create(1024, 1024);
one = tex_page_add(tpage, "one.png", 1, 64, 64);
two = tex_page_add(tpage, "two.png", 2, 64, 64);
tex_page_finalize(tpage);

// ... later, to draw:
tex_sprite_draw(one, 0, x, y);
tex_sprite_draw_ext(two, 1, x, y, 2, 2, current_time / 3, c_white, 1);

Example (2.3)

tpage = new TexPage(1024, 1024);
one = tpage.add("one.png", 1, 64, 64);
two = tpage.add("two.png", 2, 64, 64);
tpage.finalize();

// ... later, to draw:
one.draw(0, x, y);
two.drawExt(1, x, y, 2, 2, current_time / 3, c_white, 1);

API

See doc22.html and doc23.html in export directory.

Compiling Haxe->GML

• Install Haxe
• Install sfhx via
  haxelib git sfhx https://github.com/YellowAfterlife/sfhx
• Install sfgml via
  haxelib git sfgml https://github.com/YellowAfterlife/sfgml
• Do haxe binpack.hxml to compile all versions.

This will update all 3 GameMaker projects.

Approach

Since packing happens at runtime, the approach used is one of the simplest possible - the algorithm finds the first child-less rectangular node in the tree that can fit an image, marks it as a container for it, and divides it into three - now-image-sized node itself, and two children filling the remaining space:

+-------+    +---+---+
|       |    | E |   |
|   E   | -> +---+ B +
|       |    | A |   |
+-------+    +-------+

Split direction depends on remaining width/height after subtracting image size.

I do not know the algorithm name off-hand as this is loosely based on an example I made for someone in 2012.

Authors, license

Vadim "YellowAfterlife" Dyachenko

MIT license