How can I change the FOV but not speed using commands?

Question

Is there a way to change the field of view using a command in Minecraft, without changing the walk speed? I'm talking about the option that, at its max, is labeled "Quake Pro".

I'm working on a top-down adventure map where the player is placed above a world (20 blocks or so) with FOV=30. When you get into a fight every 10 block walks or so it'll teleport you into a battle field where ideally your FOV would be around 70 (normal).

I tried increasing the speed effect of the player inside of fights but it's uncomfortable to fight when you're walking much quicker than normal.

I could slow down the walking speed of the player outside of battles, but then you get the same problem - you end up walking too slowly on the world map, and that's no good either.

EDIT: PS The method should work in 1.10.

Answer 1

If it's not a problem, you can apply a speed debuff to armour through the use of attributes. If you do this, you can increase both the speed and the FOV with the Speed potion effect, then the attribute modifier on the boots will slow the player down. It'd take ages to tinker with and may have some odd consequences when jumping.

Just use this command as a base to start with to give the players boots, and play around with both the potency of the speed effect and the modifier on the boots.

/give @a minecraft:leather_boots 1 0 {AttributeModifiers:[{AttributeName:"generic.movementSpeed",Name:"speedDebuff",Slot:"feet",UUIDMost:1,UUIDLeast:1,Operation:1,Amount:-0.1}]}

Change the Amount:-0.1 at the end. This currently modifies the players speed by -0.1, or -10% (they're the same thing).