I was bit confused how a formula that depends on a constant frame rate works with variable refresh rate. Then the author commented that you don't need to calculate the quantity that depends on frame rate in code. https://news.ycombinator.com/item?id=40401211

I'm really lost, but alas have ~0 experience with 3D about 15 years into a career.

Ignoring variable frame rate: 1. Doesn't the frame rate depend on the display hardware?

2. Can you know the frame rate at runtime?

Variable frame rate: 3. What quantity do you use for frame rate for variable frame rates?