Game Maker Tower Defence tut

[Fireblade]

This is a tutorial of how to create a Obj_Enemy and Obj_Tower that interact with each other. As in, the tower will shoot back at a certain range. And the enemy will spawn, go along a path, and you will beable to build more towers.

Note: I work to get the job done. xD there are others better then me xD

My tower will be able to rotate, this could be very difficult if your sprite of the tower is not suited for rotation, if you do not want it to rotate, then remove every line of the image_angle = Point_direction. i mean the WHOLE LINE

if you change names of your objects, you need to change the names of them in the code.

if you follow my guide, make sure everything here is also capitalized in your game as names.

This tutorial mostly ment for tower and enemy, the spawning of the enemys will spawn

1st:
Build a Obj_Tower, new sprite, name it Spr_Tower(any name works, but coding it could be difficult if your n ot organized)

Make a Obj_Bullet (sprite too)
Make a Obj_Enemy


2nd: now lets make the Obj_Tower

on create

shot = 1

on alarm 0

shot = 1

on step

//This code makes gets the nearest enemy, and if its in distance (75 or lower)
//Then it creates a bullet!
Enemy = instance_nearest(x,y,Obj_Enemy)

if (distance_to_object(Enemy) < 76) then
    {
        image_angle = point_direction(x,y,Enemy.x,Enemy.y)
        if shot = 1
        {
            instance_create(x,y,Obj_Bullet)
            shot = 0
            alarm[0] = 100
        }
    }

now Obj_Tower is ready.

3rd: create Obj_Path, make it a 32X32 green object with transparency off if you want it simple.
make Obj_Path solid. depth 1.

4th: create a path followed by your path in a room. named Path_Enemy


create Obj_End 32x32 and place at the end of your path
make it solid






5th:
Obj_Enemy

on create:
[CODE]hp = global.hp/CODE]
and set path Path_Enemy at end stop relative (sorry dunno code for this)

on destroy:

global.money = global.money + 3

on step

if hp < 1 then
{
    with (self) instance_destroy();
}

collision with bullet

hp = hp - 34

with (other) instance_destroy();

collision with Obj_End

global.live = global.live - 1
with (self) instance_destroy();
global.money = global.money - 3

6th:
Obj_Bullet
on create

Enemy = instance_nearest(x,y,Obj_Enemy)

move_towards_point(Enemy.x,Enemy.y,2);

7th:
Create Obj_Tower_Icon, and make it solid.
place it at the bottom left of the room.
On Mouse left RELEASED

if (instance_number(Obj_Tower_Place) = 0) && global.money > 4 then
{
    instance_create(mouse_x,mouse_y,Obj_Tower_Place)
    global.money = global.money - 5
}

note: there is no global.money yet.

8th: create Obj_Tower_Place, and set sprite to Spr_Tower
on create:

image_alpha = 0.5;

(sorry about this part not being code, i forget how to code theese in code)

on step
Use jump to a given position icon
x = mouse_x
y = mouse_y

on mouse left released
If there is NOT a collision at x,y with only solid
{ (start of block)
create instance Obj_Tower x,y
destroy self
} (end of block)

on right released

with (self) instance_destroy();
global.money = global.money + 5

8th:

create Obj_Control with no sprite, place on map

on create:

global.money = 10
global.hp = 68
global.hpboost = 7
global.live = 20
global.time = 0
alarm[0] = room_speed*5
alarm[1] = room_speed*120
alarm[2] = room_speed*180
alarm[3] = room_speed*240
alarm[4] = room_speed*300
alarm[5] = room_speed*1

alarm 0

instance_create(32,0,Obj_Enemy)

global.hp = global.hp + global.hpboost

alarm[0] = room_speed*5

alarm 1

global.hpboost = 8

alarm 2

global.hpboost = 9

alarm 3

global.hpboost = 10

alarm 4

global.hpboost = 11

alarm 5

global.time = global.time + 1
alarm[5] = room_speed*1

on draw
draw variable global.money x=0 y=432
draw variable global.live x=0 y=400
draw variable global.time x=0 y=368
draw variable global.hp x=0 y=336








you can get the gmk that works, as i found many errors making this tut and doing the gmk tut
this tut does not destroy the bullets, wich later will lag the game

important! the gmk is forgeting 1 thing, make the towers SOLID