Hello! I'm back and in this blog I want to talk about shading, but just the basics. I won't be going over mirrors or specularity in this post. That is a more advanced topic that should be explained separately in my opinion. But let's go over the basics of shading and some examples.
Light and Wall Example
First, imagine a light and a standard wall perpendicular to the light , such as a light bulb and a drywall in a house.
Well then the light is just going light up the wall right? Pretty much, yeah. There's a little more to it, but I'll explain it later when it would make more sense.
Light and Curve Example
What about the same light, except this time the wall is a half-circle like this? Maybe instead of a drywall in a house, it could be a pillar.
Well now things are just a little different, but the point on the curve where the arrow hits perpendicularly is where the ray of light would hit most effectively, and this applies to the flat wall as well.
Estimating Amount of Light
An easy way to estimate how much light or shadow you should use when shading things is to identify any point on a surface that you want to shade and then imagine a plane flat against that surface. For examples:
The more perpendicular the ray of light hits the plane, the stronger the light will be at that point on the surface. And the opposite is true as well: the closer the ray of light is to being parallel with the tangent, the weaker the light will be. This method also works for 3D objects.
In this example below, the blue plane is unexposed to the light source, so the yellow point doesn't receive any (additional) light.

Then once you understand this concept, you'll realize that this applies to shading many other things, such as this muscly arm by ShahmiMSD on DeviantArt (notice the shading of the veins too).

That explains the basics of shading. I hope you found this blog helpful!