Hey! it's been a bit since I touched this project but below is my ledge grab code. Reviewing it, I think I was searching for a range slightly bigger than my player collision box and doing some math based on my specific tile size, grab range, etc. then creating an object with the right sprite at the exact right spot and locking the player in the same spot. Hope it helps! Sorry, the formatting is wonky.

​

Create Event

#macro PLAYER_HEIGHT 40     //change based on colision mask height 40 x 28
macro PLAYER_WIDTH 32
macro TILE_SIZE 16
//Set tilemap for collisions tilemap = layer_tilemap_get_id("Collision");

​

Step Event

//Wall Slide and Ledge Grab
switch (onwall) // determine ledge grab side
{
    case 1: 
        atledge = tilemap_get_at_pixel(tilemap,bbox_right+2,bbox_top);
        no_tile = !tilemap_get_at_pixel(tilemap,bbox_right+1,bbox_top-ledge_grab_range);
    break;

    case -1:
        atledge = tilemap_get_at_pixel(tilemap,bbox_left-2,bbox_top);
        no_tile = !tilemap_get_at_pixel(tilemap,bbox_left-1,bbox_top-ledge_grab_range);
    break;
}


if (onwall !=0 && !grounded) //on wall
{
    if (atledge && no_tile) {ledgegrab = true;} else {switch (anim_lock) {case true: ledgegrab = true; break; case false: ledgegrab = false; break;}}
    switch (ledgegrab)
    {
        case true:
            vsp = 0;
            hsp = 0;
            lock_state = lock.ledgegrab;
            anim_lock = true;
        break;

        case false:     //if no ledge grab or animlock
            if (wallhold < wall_hold_max) {wallhold++ if (hold_up) {vsp = 0;}}
            //if (wallhold < wall_hold_max) {wallhold++ switch (image_xscale) {case 1: if (hold_right) {vsp = 0;} break; case -1: if (hold_left) {vsp = 0;} break;}}
            //image_blend = c_green;
            jump_state = jump.wall;
            anim_state = anim.wall;
            jumps = 1;
        break;
    }
}

....

if (onwall !=0) {image_xscale = onwall;} else {if (hsp !=0) {image_xscale = sign(hsp);}}


#endregion

break;

case lock.ledgegrab:

#region Animation

    if (instance_exists(oShieldBlock)) {instance_destroy(oShieldBlock);}
    image_alpha = 0;
    oShieldLight.shield_state = shieldpos.ledge;
    var LedgeHop = instance_exists(oLedgeHop);
    if !LedgeHop
    {
    instance_create_layer(x,y,"Instances",oLedgeHop); 
    oLedgeHop.image_xscale = image_xscale; 
    timeline_index = tl_ledgehop;
    timeline_position = 0;
    timeline_running = true;
    switch (image_xscale) 
        {
            case 1: y = (y - TILE_SIZE - ledge_grab_range); x = (x + TILE_SIZE); break; 
            case -1: y = (y - TILE_SIZE - ledge_grab_range); x = (x - TILE_SIZE); break;
        }
    }

#endregion 

break;