How to correctly get liquid in a glass.
First, the three methods from left to right.
The left one is the most incorrect. There are 2 bodies, the glass and the liquid. The liquid body intersects with the glass part (both surfaces of the bodies are in the same space) creating a banding effect.
The middle one has the liquid body scaled down a notch. This works for renders where the glass is in the distance. However as you can see, the liquid does not appear to go all the way to the outer surface of the glass body.
The one on the right is the correct one, with the liquid "touching" the outer surface of the glass body.
Here you can see what the difference is in solidworks
The solution is to create the top surface of the liquid as a surface, and assigning the same material to the inner wall of the glass. Create the split line if its missing from your model.
Here a reference to show that the liquid in a glass really does seem to touch the outer side of the glass.
So, how to do this?
First, create your glass.
Then, add a "line" where the top of the liquid will be.
Use the split tool to create a line in the surface, only select the line and the inside surface of the glass.
And there you have it, an intersection line.
Now, create a surface top, make sure the end of the sketch line touches the line you just made on the glass surface. Don't forget to add the vertical construction-line.
And revolve this with surface revolve.
Then, give the inside surface of the glass and the top-surface the same material.
And import your model to keyshot!