Shooter

1. Make objects for oPlayer, oLargeAsteroid, oSmallAsteroid, oControl, oBullet, as well as the corresponding sprites
2. Update oPlayer to move in all 4 directions
3. Update oPlayer to angle toward the mouse and shoot oBullet objects on mouse click
4. Update oLargeAsteroid to start with a random(ish) rotation speed, direction, and speed
5. Update oControl to spawn oLargeAsteroid objects along the edge of the screen
6. Update oLargeAsteroid to explode into the smaller asteroids when it collides with oBullet
7. Update oSmallAsteroid to award points when it collides w/ oBullet
8. Store & display a persistent high score across game runs
9. Add a paritcle effect to the small asteroid death

Previously we’d have a variable max_speed, and then we set dx or dy to that value depending on the direction that we’re moving

If they’re both at max_speed then their combination results in a higher speed, and that looks kind of weird

There are a couple ways to fix this, one is to chain a bunch of if statements to handle all the combinations (if(left and not up and not down), if(right and not up and not down), etc)

One of the better ways, imo, is to leverage polar as follows

var input_x = keyboard_check(vk_right) - keyboard_check(vk_left);
var input_y = keyboard_check(vk_down) - keyboard_check(vk_up);

var input_dir = point_direction(0, 0, input_x, input_y);

dx = lengthdir_x(max_speed, input_dir);
dy = lengthdir_y(max_speed, input_dir);

Here I combine the booleans from the keyboard functions (remember boolean is just 0, or 1, so doing math on them is fine). This gives us -1, 0, 1 for each

From there we can get a direction (point_direction() is just math, it doesn’t care if you’re giving it actual room coordinates). For example, if you’re going up and to the right, we get 1 and -1 for input_x and input_y. Then if you run point_direction(0, 0, 1, -1) you get 45. Voila 🥐!!

I want them to start outside the room, and I can split that into to cases. top/bottom or, left/right

For top/bottom, I can use random_range(-64, room_width+64) for x and choose(-64, room_height+64) for y, and I can do something similar for left/right

I spawn new asteroids in on oControl alarm event, and then in the alarm event and reset the alarm so that it will retrigger later

I have a variables, let’s say spawn_steps, that determines the new value when reseting the alarm

So we just need to decrease that over time, for me I put spawn_steps *= .999; in the step to reduce it over time

WARNING: At first I put spawn_steps *= .8 in the alarm event, but that was really weird. Since it was reducing more often as the alarm was triggered more often there was a point where it would reduce super fast, and all of a sudden I had a thousand asteroids on the screen 😬 (totally worth a try for the experience though)

Ah, you’re talking about friction. Flying in space is a lot like walking on ice, when you try to stop moving it takes a while to slow down. The ground has high friction which slows, you down, space and ice have low friction

I’ll use the code from the diagonal movement question as a starting point

var input_x = keyboard_check(vk_right) - keyboard_check(vk_left);
var input_y = keyboard_check(vk_down) - keyboard_check(vk_up);

var input_dir = point_direction(0, 0, input_x, input_y);

dx = lengthdir_x(max_speed, input_dir);
dy = lengthdir_y(max_speed, input_dir);

here’s how you make it use friction

var input_x = keyboard_check(vk_right) - keyboard_check(vk_left);
var input_y = keyboard_check(vk_down) - keyboard_check(vk_up);

var input_dir = point_direction(0, 0, input_x, input_y);

dx += lengthdir_x(max_acc, input_dir);
dy += lengthdir_y(max_acc, input_dir);

dx *= fr;
dy *= fr;

var sp = point_distance(0, 0, dx, dy);
if(sp > max_sp){
	dx *= max_sp / sp;
	dy *= max_sp / sp;
}

dx += lengthdir_x(max_acc, input_dir);: 2 subtle differences here. First I use += instead of =. This means we’re adding acceleration to the previous speed, rather than directly setting the speed. Also I updated max_sp to be max_acc since it now represents acceleration

dx *= fr;: fr is a variable between 0 and 1. Here I make the speed smaller every step, that way if you stop moving, friction will slow you down over time. Something like .2 will make the friction slow you down very quickly, where as .999 would be very slow

if(sp > max_sp){: With the acceleration, the speed can get really crazy, so I still want to enforce a max. I used point_distance to get my current speed, then if its above max_sp, I multiply both components by max_sp / sp to scale it. So if sp is double max_sp, then max_sp / sp will end up multiplying both components by .5

Sure, just check for when the player is outside room and add or subtract the width or height of the room accordingly. I beleive in you 😀

Yes you can! I actually made both asteroids children of an oDeadly parent. That way, when checking for collisions oPlayer only needs to check for oDeadly instead of both asteroids. This will also extend nicely if you add more enemies to the game

Sure thing!

One adjustment I added is to make the ship constantly shoot instead of requiring mouse presses. Here’s a Game Design rule of thumb: “For each of the player’s abilities, there needs to be a reason to use the ability as well as a reason not to use the ability”. So for example, in most games the reason you shoot is to kill things, and the reason not to shoot is to save your ammo. But our game doesn’t have ammo, so why not just have the ship always shoot? (also my hand was starting to hurt, and I was tired of clicking)