What is Laigter for?¶
Laigter is mainly an automatic normal map generator focused on 2D Sprites. You just need to drag and drop your images into Laigter, and a normal map will be generated for you. Then you can play around with controls to adjust the map to get better results for your use case. You can also preview dynamic lighting in real-time, to check how the generated maps will affect lighting in-game.
Laigter also lets you generate and edit other maps, like specular, parallax, and occlusion, although they are a bit less used in 2D games compared to normal maps.
Once you are convinced by the results, you can export each map, and use them in your game to create cool dynamic lighting effects with minimal effort!
What are normal maps?¶
Normal maps are 2D textures which stores the direction of the normal vector to a surface on its RGB channels. This way, they can be used in a shader to calculate how light should interact.
Normal maps are more often used in 3D games to achieve high-quality lighting at a low cost. A 3D model is composed of tiny triangles; each of one has a normal vector (unit vector perpendicular to the triangle’s surface). So light can bounce and reflect according to that normal. However, to achieve high-quality results, the model should have a lot of triangles, which increases the computational cost. With normal maps, you can get a per-fragment normal, only needing to pass a texture with the information of the normal vector on its RGB components. Then, this can be used to achieve a more detailed light interaction with a very cheap GPU cost.
In 2D games, this is more noticeable, as we don’t even have surfaces with normal vectors to calculate lighting. We only have a flat Sprite, so all lighting looks flat. Using normal maps, we can give the illusion that the Sprite has some kind of volume when it is affected by light.
Normal Map Example¶
The following image shows a normal map example.
But, how does a normal map store the normal vector on an RGB image? The concept is quite simple. It stores the x, y, and z components of the vector on the R, G, and B channels correspondingly, but with a small change.
On the one hand, a normal vector is a unitary vector (its length is equal to 1), and you only need values from -1 to 1 to represent each axis. On the other hand, RGB can store values from 0 to 1, so the normal map has the components of the vector scaled by 0.5, and with a 0.5 offset.
Following this technique, the vector (0.0, 0.0, 1.0) ( a normal vector pointing directly to screen) would transform into (0.5, 0.5, 1.0). In a nutshell, this is the reason why normal maps have that blueish color.
Why choosing Laigter?¶
There are other cool normal maps generators out there, but Laigter is free and open source. This means you can grab the code yourself and implement missing features if you need so, modify it, distribute your modified version to the public, and many other freedoms open source gives.
Also, Laigter is extensible through plugins, so you can make your own extensions and distribute/sell them freely.
Laigter is simple to use, you just need to open your images and tweak some controls. The real-time preview lets you check the result immediately. Laigter’s rendering is done in OpenGL 2.x standard, so it can be run on old machines.
Here is how my current game looks like, using Laigter to create normal maps: