Need help using arrays

[gobbel]

4.3.stable.official

hi, below is a part of my context-based steering script. it shoots i rays, and if it detects something in that direction, sets the corresponding index in the danger array to 5, if not, to 0.
What i would like it to do though is set the directions adjacent to the danger directions to 2. what i tried first was simply set the indexes i + 1 and i - 1 to 2, but that has two problems, first, if i set index 4+1 to 2, then next i’ll override it by setting index 5 to either 5 or 0. also when you try to access idex 0 - 1 or 8 + 1, the game crashes as those indexes dont exist. how would i go about doing this? basically what i need is for every index that doesnt detect a danger, but is adjacent to an index that detects danger, to be set to 2.

func set_danger():
	var space_state = get_world_3d().direct_space_state
	for i in num_rays:
		var query = PhysicsRayQueryParameters3D.create(position, position + ray_directions[i] * look_ahead)
		query.exclude = [self]
		var result = space_state.intersect_ray(query)
		if result:
			danger[i] += 5.0
		else:
			danger[i] = 0

[tshadow999]

You could do a second loop this time looping over the danger array, to update the neighbours only if their value is not already 5 (same as being equal to zero)

[gobbel]

but how would i only update the ones that have neighboring 5’s? For example, if index 7 has a 5, i would need to update index 6 and 0

[regnarok]

Something like this

var idx_num := 0
var change_value: Array[int] = []
for idx in danger_array:
     If not idx == 5:
          idx_num += 1
          Continue
     If danger_array[(idx_num - 1 + danger_array.size()) % danger_array.size()] != 5
               change_value.append((idx_num - 1 + danger_array.size()) % danger_array.size())
     If danger_array[(idx_num + 1) % danger_array.size()] != 5:
               change_value.append((idx_num + 1) % danger_array.size())
     idx_num += 1
for value in change_value:
     danger_array[value] = 2

I edited this due to tshadows suggestions, just to make sure he has credit for the simplified code.

Also, I didnt know if your array had a fixed size, that is why why I used size(), but if it is fixed size you can just replace it with the size ie an array with max index of 7, the size would be 8.

[tshadow999]

you would use the modulus operator (usually: % or mod).
This gets the remainder of division.
So your array is 8 long, and you want to check index 7 neighbours.
You do (7+1) mod 8 = 1 with remainder zero. meaning 8 mod 8 = 0.

[regnarok]

That works nicely for larger, though smaller wouldn’t work.

[tshadow999]

It will work, to check the previous one, instead of (i - 1) mod 8
use (i - 1 + 8) mod 8

Or use the posmod(i - 1, 8) method

[gobbel]

This works like a charm! Had to add a special case for when i = 0, otherwise it tries to divide by zero and crashes thanks a ton

[gobbel]

thank you lots for your help! i got it working