Basic lighting concepts for gamedevs (work in progress)
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Note to self and editors: This article should cover real world lighting concepts from physics, but also cover lighting in the context of game development, a separate article should cover different settings withing lighting objects (directional light, rect light) I may want to put explanation about methods like global illumination, reflections and antialiasing in here?
It is important to differentiate the multiple circumstances that a surface can be in, since different lights, methods, settings, etc. need to be used to solve different lighting issues
Direct lighting
As the name implies it's when a light hits a surface and lights it up, direct lighting can be split into diffuse and specular/reflection despite them looking very different from each other in physics, they're all still considered reflections
(don't pay attention to ambient light)
Diffuse lighting
is when a surface scatters the light heavily, this is caused by the fact that the surface is non-uniform with a lot of bumps and grove on the surface scattering the light in all directions. Because of this, looking at the surface from different angles can have very little effect on the reflection of the surface you see
Reflections
are the opposite of diffuse lighting, because the lighting is not scattered it is reflected uniformly, causing it to reflect everything perpendicular to the normal.
Just stand in front of a mirror and see how the things you see in the mirror change
as you move from left to right
Specular
In mathematics and physics, specular and mirror reflections are considered the exact same. https://en.wikipedia.org/wiki/Specular_reflection
So in the context of computer graphics it's a bit odd. The definition is that specular: is the diffused reflection of an object on to a surface, which creates a bright highlight. To give you a guide to what it means in practice, just know that every time that you look at an object that isent reflective like a rock, grass, snow, etc. when you see a bright reflection that is view dependent, (changes based on the position you look at the surface) you know that you're dealing with a specular highlight
Unlit surface
This is when you have an object that doesn't get any direct lighting from a light source, as an example with only a directional light looking straight down, the sides of this wooden floor are dark. Using an extra light, global illumination or a skylight, might be used to fix this issue
Surfaces withing shadows
There seems to be no difference between how settings influence shadows cast from one object to another, or a shadow cast from the same object onto itself