This is probably a silly question to ask but I have been scratching my head over this for a while now. What does Specular really do? What is the difference between Specular vs Metallic/Roughness. Don't i get the same result if i just set the roughness down to 0? What Real-Life object use Specular? and when should I use it? Diagrams/Images would be helpful.
asked Jun 30 '16 at 07:33 PM in Using UE4
The Roughness input literally controls how rough the Material is. A rough Material will scatter reflected light in more directions than a smooth Material. This can be seen in how blurry or sharp the reflection is or in how broad or tight the specular highlight is. Roughness of 0 (smooth) is a mirror reflection and roughness of 1 (rough) is completely matte or diffuse.
The Metallic input literally controls how "metal-like" your surface will be. Nonmetals have Metallic values of 0, metals have Metallic values of 1. For pure surfaces, such as pure metal, pure stone, pure plastic, etc. this value will be 0 or 1, not anything in between. When creating hybrid surfaces like corroded, dusty, or rusty metals, you may find that you need some value between 0 and 1.
The Specular input should not be connected and left as its default value of 0.5 for most cases. It is value between 0 and 1 and is used to scale the current amount of specularity on non-metallic surfaces. It has no effect on metals.
You can read more about it here: https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/PhysicallyBased/index.html
answered Jun 30 '16 at 08:51 PM
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