Add Vector takes the Main Input component values and adds to the component values of Input 2.
Component values in vector form are refereed to as X, Y and Z.
The Output maths of this node can be written: (Main Input X + Input 2 X) , (Main Input Y + Input 2 Y) , (Main Input Z + Input 2 Z)
Vectors share common attributes to Colours in that they too consist of 3 parts, red, green and blue, which are what the preview panels are showing.
We can't natively show values beyond 2 in preview panels, so we've substituted a proxy output box (an off screen Constant Vector node) to show output values for illustrative purposes.
Add Vector_01.jpg
If Input 2 is disconnected, the Main Input passes through to the Output.
Add Vector_02.jpg
If the Main Input is disconnected, nothing passes through.
Add Vector_03.jpg
There is no limit to the value of each component in a vector and often can be quite large in your scenes depending what the source is. They also don't necessarily have to be positive either.
Add Vector_04.jpg
If one of your sources is Scalar, the Scalar value will be added to each component.
Add Vector_05.jpg
If the source is using colour, the red value will be added to the X, green to Y and blue to Z. Notice that this node is only interested in the sources component data and ignores displacement.
Add Vector_06.jpg
If there's any errors, omissions or questions about the above, please leave a comment below.
https://planetside.co.uk/wiki/index.php?title=Add_Vector