GameMaker [SOLVED] Collision Line Troubles

[Blaize]

Ok, so right now, I'm using collision_line() in a Megaman.exe-style game as part of a sensor-like function.
So, let's have a look at this image:

Spoiler: Image 1

https://imgur.com/a/giD9v

Ok, so the one with the green square is the player and everything else is an enemy. The white rectangle is our player's collision line. It's origin is from the left or right bbox, depending on which way it's facing (ie. Right uses bbox_right, left uses bbox_left).
Now, when facing right (as in the image), collision_line will return 100007, as expected.
However:

Spoiler: Image 2

https://imgur.com/a/Zlj62

In this situation, collision_line will still return 100007 instead of the one closer to the player.

I've been wrestling with this for a while, but still can't get my head around it.
Here's my code:

Spoiler: Player Step

#macro COMBATGRID 64 (This is in a Macros script)
if (_attack && AttackTimer == 0)
{
    var _xOrigin = x+(Facing==1?bbox_right:bbox_left); //Facing == 1 means right; -1 means left. 0 is disregarded
    var _hit = collision_line(_xOrigin,y+(COMBATGRID/2), (Facing==1? room_width : 0),y+(COMBATGRID/2),pCombatActor,false,true);
with (_hit)
            show_debug_message("Hit "+string(id));
}

I have a feeling that it is picking up both, but returning the instance with the lower ID? Could be wrong
Much appreciated.

 

[Alex_Beach]

Your collision line is is hitting 2 objects, but the function can only return 1 ID at a time, that's the problem (it probably priorities the lower value). So, I would make your line extend 1 box at a time until it hits an object, or misses offscreen. Example: Make short line, check for collision. If no collision, make line longer and check again. I had a similar issue with a puzzle game, so I approached it this way and it worked.

 

[Blaize]

Your collision line is is hitting 2 objects, but the function can only return 1 ID at a time, that's the problem (it probably priorities the lower value).

Yeah I thought as much.

So, I would make your line extend 1 box at a time until it hits an object, or misses offscreen. Example: Make short line, check for collision. If no collision, make line longer and check again. I had a similar issue with a puzzle game, so I approached it this way and it worked.

Hm, that might work, though it may become taxing on the game if there were multiple characters doing the same calculations. Eventually, there will be some enemies which will have similar abilities to the player themselves.
I'll definitely try it out, though.

 

[hogwater]

There is a script called "collision_line_list" or something that returns a list of the instances colliding with the collision_line function. Pretty sure it's on GMLscripts.com, that may help.

 

[Blaize]

There is a script called "collision_line_list" or something that returns a list of the instances colliding with the collision_line function. Pretty sure it's on GMLscripts.com, that may help.

Oh yes I found it, here: http://www.gmlscripts.com/script/collision_line_list
I wonder if it will impact the speed though. I'm sure it won't since I don't plan to have more than 5 objects on screen (enemies + player), but thanks, I'll try it out.

 

[Nocturne]

Personally, I'd use this one... http://www.gmlscripts.com/script/collision_line_first

You only want the first collision and the script is probably faster than the other one as it's pure maths (no data structures required).

 

[hogwater]

Even better.

 

[Blaize]

So I've tried both out and, after making the appropriate tweaks to collision_line_first() for my needs, this is solved!

Cheers, folks!