obj_astar_step

if (keyboard_check_pressed(vk_space))
{
    //reset the previous path - make blue nodes white
    //and recolour start and end nodes
    for (var i=0;i<ds_list_size(pathNodes);++i)
    {
        var inst = ds_list_find_value(pathNodes,i);
        with (inst)
        {
            image_blend = c_white;
        }
    }
    with (startNode)
    {
        image_blend = c_green;
    }

    with (endNode)
    {
        image_blend = c_red;
    }

    ds_list_clear(pathNodes); //clear the list of nodes
    //find the path between start and end nodes
    //and make the variable true if a path is found, else false
    found = scr_findPath(startNode,endNode,pathNodes,maxRange);
    //colour all the nodes between the start and end nodes with a blue colour
    for (var i=1;i<ds_list_size(pathNodes)-1;++i)
    {
        var inst = ds_list_find_value(pathNodes,i);
        with (inst)
        {
            image_blend = c_blue;
        }
    }
}

//left click = make selected node a start node
if (mouse_check_button_pressed(mb_left))
{
    var inst = instance_nearest(mouse_x,mouse_y,obj_node);

    with (inst)
    {
        if (distance_to_point(mouse_x,mouse_y) <= radius)
        {
            with (obj_astar.startNode)
            {
                image_blend = c_white;
            }

            obj_astar.startNode = inst;
            image_blend = c_green;
        }
    }
}

//left click = make selected node an end node
if (mouse_check_button_pressed(mb_right))
{
    var inst = instance_nearest(mouse_x,mouse_y,obj_node);

    with (inst)
    {
        if (distance_to_point(mouse_x,mouse_y) <= radius)
        {
            with (obj_astar.endNode)
            {
                image_blend = c_white;
            }

            obj_astar.endNode = inst;
            image_blend = c_red;
        }
    }
}