Learning 3D - Part II: Adding color, texture & light

Learning 3D is a quick and simple series for new Sketchfab users to explore and learn about the basic principles of 3D. These tutorials will offer a foundation of knowledge and prepare you to create your own 3D models or scans on software outside of the Sketchfab platform. 

Now that we know what defines the shape of a 3D model, we can explore how to add some color, texture, and light.

Adding colors

A simple way to add colors to a face is to use vertex colors.

A vertex color is color information given to a particular vertex. All the points placed in 3D space that define the shape of a model can be colored.

Interpolation (as we learned about before) allows the colors between all the vertices to be computed automatically to give colors to the whole shape.

Adding textures

Another way to add more to a 3D model is by applying textures.

A texture is basically a 2D image placed on a 3D model, including some data called UV coordinates. The UV coordinates determine where exactly to apply (or map) the texture on the model. This mapping process is simply called texture mapping.

UV coordinates are data attached to each vertex to define how they should stand on a texture. In other words, UV coordinates help answer the question “Where in the image are my vertices supposed to be?” The action of creating or modifying UV coordinates is called UV unwrapping.

In the Sketchfab Inspector, you can see a model's 3D view side-by-side with the 2D view of the selected texture in the Viewport: 

Adding lights

Finally, you can add lights to make your 3D model look more realistic.

For each light source, you need to define a position, an orientation, an intensity and a color.

There are several types of lights available on Sketchfab:

Plus, you can apply (or import) an environment to affect your model's lighting. An environment offers a 360° panorama background for your models, and will affect your model's lighting and reflections.

Now we know that data for your model's orientation, colors, texture mapping, and lights are all attached to the vertices. But what computes everything?

Shader

The shader is a piece of code that takes all the data we've learned about so far, and gives life to the pixels on your screen.

It works like a factory full of people who each handle a specific task. Worker 1 will take the info on the orientation and process it. Worker 2 will focus on colors. Worker 3 on texture mapping, etc.

Up next: Learning 3D - Part III: Create your own models