Support setting camera roll via lua

[regulus79]

Goal

To make it possible to set the roll of the player camera through lua code

How it works

• This PR adds two new functions to the lua api, namely player:set_look_roll(radians) and player:get_look_roll().

• player.h now has a new property camera_roll which stores the current roll angle of the camera.

• Two new functions are added to server.cpp/.h to assist in sending the function call to the client.

• A new client/server code is also added to handle the setter function call, TOCLIENT_CAMERA_ROLL

• The lua_api.md was updated accordingly.

To do

Maybe not in this PR, but sometime it would be good to enable interpolation, as Herowl suggested on the discord.

Status

This PR is Ready for Review.

How to test

Using worldedit:
//lua minetest.get_player_by_name("singleplayer"):set_look_roll(math.pi/2)

[appgurueu]

Thanks for the PR. I'm giving this a concept approval because currently I don't see significant risk of breakage; this is a useful feature to have e.g. for immersive plane mods.

If we're adding camera roll, it might make sense to let the player inherit roll from whatever they're attached to (of course this would need to be opt-in, maybe via yet another attachment parameter, at which point set_attach should be refactored to use a table). What do you think?

Nitpicks:

• / core::RADTODEG could be * core::DEGTORAD
• I feel some blank lines are excessive
• float vs f32 feels inconsistent (I prefer f32)
• Nittiest of picks: m_camera_roll=roll; could use two spaces around the =

This PR looks fine, otherwise. I'm not sure about a separate packet for roll - why not extend the packet already used for yaw and pitch to support roll?

[epCode]

Real quick thought: I tested this out and did some experimentation, and it works great that I've seen. But something that bothers me, which is not standard in normal fpv roll, is that when your view is rotated on the z axis (roll) your pitch and yaw (mostly pitch that bothers me) still rotate on the original axis.

Example: say I have set my roll to 90 degrees, if I move my head side to side I expect it to transform the camera on MY local axis, but instead what happens is it looks like I'm moving my head up and down.

This is unoptimal for if someone wanted to make an "upsidedown" sort of mod that flips your perspective. With this implementation, the controls would feel inverted.

Just a thought, I don't know if this is in the scope of this pr, and I know that x and y axis rotations don't effect each-other, so go figure.

Thanks for your patience!

[regulus79]

I'm not sure about a separate packet for roll - why not extend the packet already used for yaw and pitch to support roll?

I agree that it would make sense to couple the roll with the pitch and yaw in one packet, but from what I can tell it appears that the player yaw and roll is sent through TOCLIENT_MOVE_PLAYER, which sends the pos, pitch, and yaw of the player every step.

Since the roll of the camera is not directly controlled by the player, I thought it would make more sense to send it through a different packet which is only called when the roll is updated. Of course, I may be wrong. Either way, it would not be too hard to bundle the roll with an existing packet if that would be more appropriate.

[JosiahWI]

the roll of the camera is not directly controlled by the player

That sounds like a good argument for not putting the new field in the Player class.

[Zughy]

(@appgurueu : you can't approve a PR directly, hence the changes. Unsubscribing)