Using lengthdir to lock object to another

[J.J.]

I have two objects (Wagon and Turret) and I want the turret attached to the wagon. I found out that lengthdir is the one to use for this. But I'm no programmer/scripter so who can help me out step for step.

 

[GMWolf]

The easiest way is to find the angle from the origins and distance of the turret.
Then, use something like:

x = wagon.x + lengthdir_x(wagon.image_angle + aoffset, offset);
Y = wagon.y + lengthdir_y(wagon.image_angle + aoffset, offset);

Where aoffset is the angle offset, and offset is the distance offset.


A more complicated approach is using matrices.
You must first find the x and y offset of the turret. Let's call them xoff and yoff.
Then, use the following code:

//build the transform matrix from the wagon
var mat = matrix_build(wagon.x, wagon.y, 0, 0, 0, wagon.image_angle, 1,1,1);
//transform our offsets
var o =  matrix_transform_vertex(mat, xoff, yoff, 0);

//get our x and y coords
x = o[0];
y = o[1];

 

[J.J.]

@Fel666 Do I put this in the creation code?

 

[GMWolf]

Do I put this in the creation code?

No, the step event.
Note - it won't work right out of the box. You should adapt it to your project.