# What is FOVx in this diagram?

a beginner game developer here. I have recently taken upon learning about 3D game development and I am stuck on a simple matrix problem.

I am trying to represent this matrix in my code but I am not sure what precisely is meant by FOVx and FOVy. What is the difference and how would I represent this in my perspective matrix? I am not using any 3D api.

• FOV is Field Of View. – Anko Dec 30 '14 at 3:52
• I understand that part, but how do I get the x and the y? What is the difference? I thought the FOV was just an angle – toshko3331 Dec 30 '14 at 3:55
• It's two angles actually: one horizontal (the x component), one vertical (y). For example, to emulate human vision, you might want to have a camera that can "see" a somewhat greater horizontal angle than vertically. – Anko Dec 30 '14 at 4:06
• Ah thank you, that actually clarifies things a lot more. I always assumed that the FOV was just a single angle. – toshko3331 Dec 30 '14 at 4:12
• That's pretty much the extent of my knowledge on projection matrices though! :) If you figure out the rest (or if that actually answers the question; I can't really tell), it's totally OK to post answers on your own questions too. – Anko Dec 30 '14 at 4:17