I need help with a angle problems

[TheFoxyHu3]

Hello. I'm trying to do a top-down shooter in lua,
but when i test the enemy, i see a problem in the angle.

I already had this problem (it's 'in the pi 'n -pi), but i don't remember how i fix...

[marclurr]

What's the problem?

[dusoft]

Hello. I'm trying to do a top-down shooter in lua,
but when i test the enemy, i see a problem in the angle.

I already had this problem (it's 'in the pi 'n -pi), but i don't remember how i fix...

Provide the code and elaborate on what your exact problem is.

[pgimeno]

So the question is, when going from angle `A1` to angle `A2` clockwise, will we find angle `a` in the way?

I think this function answers it:

Code: Select all

local function angleInRange(a, A1, A2)
  A2 = (A2 - A1) % 6.283185307179586
  a = (a - A1) % 6.283185307179586
  return a <= A2
end

Proof of concept attached. Move the ball with the mouse and change the detection angle with the mouse buttons.

For future reference, it would help us help you if you give some tips about how to reproduce the problem, what to do to test and what should happen. In this case it could have been something like this:

"Try game.love and right click somewhere on the screen to add enemies, then move with WASD. The player should turn red when it is within range and between the two visibility lines of an enemy, but it's not turning red sometimes."


@dusoft The code is already provided.

[TheFoxyHu3]

Hello. I'm trying to do a top-down shooter in lua,
but when i test the enemy, i see a problem in the angle.

I already had this problem (it's 'in the pi 'n -pi), but i don't remember how i fix...

Provide the code and elaborate on what your exact problem is.

Well, I'm trying to make enemies facing* the player.

enemies.lua

(4.52 KiB) Downloaded 107 times

Code: Select all

		--if the angle of the player is more or less than enemy then will rotate
		
	if math.atan2(plr.y-enemy.y, plr.x-enemy.x) >= enemy.a then
		enemy.a = enemy.a + .0349 
	else
		enemy.a = enemy.a - .0349 
	end

The problem is, for example, when the player.x is > enemy.x and the player.y is between enemy.y positive and negative, the enemy stops to reach playrer

[dusoft]

Maybe related, maybe not:
Are you resetting angle over 360 degrees to zero and under 0 to 360?

Also, just to make things easier, I would recommend switching to degrees instead of radians. But maybe that's just my preference.

[TheFoxyHu3]

What do you mean, redefine the angle?
I don't know what to do...

[RNavega]

What do you mean, redefine the angle?
I don't know what to do...

You can describe the same direction using different angle values. Say, 360 and 0 point in the same direction, and 330 and -390 also point in the same direction.

math.atan2() can return negative angles for some inputs -- the direction of that angle is fine and is what you expect, but the angle is not in that standard range (0, 2pi), and so your IF...THEN will fail because of that.

The code in the demo that pgimeno shared above ("angleDiff.love") shows how you can test if the output of math.atan2() is within the shortest path between two angles. Note that a ".love" file is just a renamed ZIP file, so to get to the code you need to download it and then either open with an unzipping tool like 7-Zip, or renaming it to .zip and extracting to some folder. The code is in "main.lua". (edit: You already know how to create a .love, disregard this.)

[TheFoxyHu3]

Hello! Finally works. Thank you for everyone her for help me.
(I'm need to delete post? I don't use a forum ever...)

[RNavega]

You should leave this as is, that's the great thing about forums: others with the same problem as yours can drop in from a web search and find the solution. I've solved a few things based on years-old threads, people that don't even post here regularly anymore.