Game Dev for Gamers: Women Can Read Maps

Indeed, this one can read maps! As outlined in GDG#3, a UV unwrap shows how a three-dimensional object would be peeled apart and laid on a flat surface, giving texture artists a sort of weird mess of lines to paint textures within.

“Unwrapping” defines individual sets of polygons that are (usually) facing different ways, and require a different texture, so the above building would be unwrapped like this:

So, at last, we come to beautiful, wonderful textures!

1. Textureless

I’ve either created a new word, can’t spell, or am blissfully unaware of the proper term for a model void of texture. Here is a “textureless” sphere. It’s boring. Why developers have ever bothered to add a “textureless” mode as some sort of bonus option to their games I will never understand.

2. Diffuse Map

There’s nothing additional to understand here that I havn’t already explained. The diffuse map provides the bog-standard colours for a model, and although the texture I’ve used has visible cracks in it, they still look completely smooth and flat, just like the geometry.

3. Bump Map

Bump maps add the illusion of bumps! A bump map (before being rendered as shown) is a greyscale version of the diffuse map. With this information, the bump map will define height and depth based on the light and dark areas of the image, but only with the addition of a light within the scene will the bump map appear ‘bumpy’. You can see this in the image, as the lightest and darkest areas of the model appear the most flat, and least ‘bumpy’.

4. Normal Map

The simplest way for me to describe a normal map is to compare it to a bump map: the appearance of depth and height in a bump map is shown with either dark or light (if the bump map was plain white, no areas of the model would appear to have greater height or depth, so by having dark and light next to each other, parts of the model will appear raised and lowered).

Normal maps, however, contain more information. The appearance of height and depth is represented as an RGB image rather than a greyscale image, allowing a normal map to correspond with height, width and depth (or the X, Y and Z co-ordinates of a 3D object). I think this explains why Marcus Fenix has the skin quality of orange peel.

The real beauty of adding maps like this is that 3D models can be a low(er) polygon count, allowing a game to run as smoothly as possible, yet giving the player the illusion of extra 3D detail that isn’t really there. See how bump and normal maps make our super Ready Up logo almost “pop out” in the very bottom image? Yet both these images have exactly the same number of polygons. Didn’t I tell you maps were amazing!