Add compass HUD element

[EvidenceBKidscode]

This PR adds a "compass" HUD element (new HUD feature).

Basically it is like image HUD element but it rotates or translates according to the current heading direction. This allows to build various compass HUD. The display is entirely updated on client side so it is quite smooth.

To do

This PR is ready for review.

How to test

Here is a sample code for testing it, using default mod textures :

minetest.register_on_joinplayer(function(player)
	player:hud_add({
		hud_elem_type = "compass",
		position = { x = 0, y = 0 },
		offset = { x = 10, y = 10 },
		size = { x = 150, y = 150 },
		alignment = { x = 1, y = 1 },
		text = "gui_furnace_arrow_bg.png",
		dir = 1,
	})

	player:hud_add({
		hud_elem_type = "compass",
		position = { x = 0, y = 0 },
		offset = { x = 10, y = 170 },
		size = { x = 100, y = 50 },
		scale = { x = 1, y = 1 }, -- Required or scale would be 0
		alignment = { x= 1, y = 1 },
		text = "default_ladder_steel.png^[transformR90",
		dir = 2,
	})
end)

This adds two compass HUD elements in the upper left corner of the screen (better texture would be much more suitable 😄) :

[LoneWolfHT]

I support the idea, but am not sure how the second HUD works

[Andrey2470T]

I don`t understand why the steel ladder element is needed for the compass on the screen?

[pyrollo]

I don`t understand why the steel ladder element is needed for the compass on the screen?

This was just provided as an example, I could have put anything else.
Imagine putting your own texture instead. Then it'll be up to you to create various compass, either rotating compass or horizontal bar compass.

[nerzhul]

except the comment fine to me

[nerzhul]

why 6 and not 5 ?

[SmallJoker]

5 will be minimap.
https://github.com/minetest/minetest/pull/9079/files#diff-036e439b344795cd3c89ffb3153b05d7R64

[pyrollo]

Thanks SmallJocker, that's it.
I was hesitating between having same number in the two PRs then reajust, or try to hide this detail from perspicacious eyes of core devs :)

[Andrey2470T]

As I consider if you want to know along which horizontal direction (North/South, East/West) you are currently moving, you can just press F5 and you above see info about it. I don`t understand a point of this feature.

[style-nine]

Not everyone uses F5 for gameplay. Some people reserve that strictly for debugging.

[Andrey2470T]

I think it would be nice to embed default compass and reserve for it a special key (e.g F11 or any else) to be able to activate/deactivate it. Also, shift it to right or left downer corner as it would overlap the chat text. But probably this is already other topic.

[pyrollo]

In my opinion, adding default stuff to engine is a mistake. Specific things like compass (an minimap) should be managed by game and mods. This gives much more freedom to modders to do what they want.
The given example is just an example, you can easily change the position to whatever you want, there is no default position in this PR.

[nerzhul]

i agree with @pyrollo .
Rebase is needed here. Will do some review stuff after

[pyrollo]

Rebased

[SmallJoker]

Tested, works. Few small issues.

[paramat]

As pyrollo is now a core dev, this can be merged.

Although, i am unsure this is worth adding.
A compass does not seem much needed and we already have degrees and NESW readouts in F5 for when it is needed.
A compass seems a thing you only occasionally need, so always being on-screen seems obtrusive, in this way F5 seems better.
Although i agree that a compass feature being controlled from server, games and mods is better than client-controlled.

PR #9315 hides yaw according to a privilege, perhaps this is all we need as it makes it server controlled?

[rubenwardy]

we already have degrees and NESW readouts in F5 for when it is needed

All games could just be text adventures, but that would be no fun

[paramat]

Well, that is just a snarky comment that misrepresents my comment to ridicule it.

[pyrollo]

I think Rubenwardy is right, visual effects are important in video games, they improve immersion. This PR is less about showing the heading direction than adding visual effects.

One criticism I could make to my own PR is that it is a bit limited. Such elements could also be able to point to a map point or something else. But HUD specification was too limited to do that. Maybe with #10245 it could be possible to have a very versatile "moving or rotating" image HUD element.

Example use cases:

• Compass (rotating or vertical + horizontal);
• Kind of radar indicating direction of a place;
• Another kind of radar indicating directions of mobs;

So should this PR be improved before merged ? (I guess yes)