checking if an enemy is behind the player

[Makkeonmies]

In my top-down action game I want to have it checked if an enemy is behind the player. does collision_line() work here, or only to check for objects in front?

 

[Nidoking]

collision_line tells you what's along a line. Any line. Front, back, sideways, offset, top, bottom, completely random - you just put the numbers between the parentheses.

 

[Sabnock]

How are you setting the direction of the instance you want to check if there is an enemy behind?

Once you know the physical direction you are facing it should be fairly simple to do the check.

 

[Makkeonmies]

I think

if collision_line(x, y, direction-180, direction-180, enemypar, false, false) //do stuff

works

But one more issue. It should check if the enemy is right behind the player, not miles away behind... if I use distance_to_object() it also counts the distance to enemy objects anywhere around the player; how to specifically count the distance to the object immediately behind the player object?
So that if the distance to the enemy right behind the player is f.e.x. smaller than 32, stuff happens?

 

[Bentley]

collision line takes 4 coordinates. You gave it the x1 and y1 arguments, but not the x2 and y2 arguments. Something like this should do what you want:

// Is there an enemy behind me 32 pixels away?
var x2 = x + lengthdir_x(32, direction - 180);
var y2 = y + lengthdir_y(32, direction - 180);
var enemy = collision_line(x, y, x2, y2, enemypar, false, false);
if (instance_exists(enemy))
{
    // Stuff
}

So just to clarify, you're checking a collision line behind you, 32 pixels away, for any child of enemypar. If an instance exists, you have its ID saved in enemy. If there will be lots of enemies (think of zombies chasing you) you can use collision_line_list to get all of their IDs in a list and then you loop through that list.

 

[Makkeonmies]

collision line takes 4 coordinates. You gave it the x1 and y1 arguments, but not the x2 and y2 arguments. Something like this should do what you want:

// Is there an enemy behind me 32 pixels away?
var x2 = x + lengthdir_x(32, direction - 180);
var y2 = y + lengthdir_y(32, direction - 180);
var enemy = collision_line(x, y, x2, y2, enemypar, false, false);
if (instance_exists(enemy))
{
    // Stuff
}

So just to clarify, you're checking a collision line behind you, 32 pixels away, for any child of enemypar. If an instance exists, you have its ID saved in enemy. If there will be lots of enemies (think of zombies chasing you) you can use collision_line_list to get all of their IDs in a list and then you loop through that list.

big thanks. completely forgot about lengthdir . Ill try this one out when i get to go back to my project!

 

[Makkeonmies]

collision line takes 4 coordinates. You gave it the x1 and y1 arguments, but not the x2 and y2 arguments. Something like this should do what you want:

// Is there an enemy behind me 32 pixels away?
var x2 = x + lengthdir_x(32, direction - 180);
var y2 = y + lengthdir_y(32, direction - 180);
var enemy = collision_line(x, y, x2, y2, enemypar, false, false);
if (instance_exists(enemy))
{
    // Stuff
}

So just to clarify, you're checking a collision line behind you, 32 pixels away, for any child of enemypar. If an instance exists, you have its ID saved in enemy. If there will be lots of enemies (think of zombies chasing you) you can use collision_line_list to get all of their IDs in a list and then you loop through that list.

works fine indeed. big thanks @Bentley !! also @Nidoking @Sabnock !