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You have completed Unity Basics!
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Let’s give the player some challenge and create our pipe obstacles and get them moving across the screen.
Unity 6 Documentation
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Okay, we got our player moving,
now it's time to start
0:01
adding the challenge to our game.
0:03
If we look back at our completed preview,
we see that these obstacles consist of
0:05
two pipes, one on top, and one on bottom,
with a gap in between them.
0:09
Also, they both move together as one, so
0:14
we know they need to stay connected
somehow.
0:16
So let's create a new square game object,
0:20
and name it bottom pipe.
0:27
I'll reset the transform,
0:31
and I'll use the shortcut T
to get our Rect tool
0:34
and scale its Y a bit.
0:37
We know that we're going
to want our player
0:41
to collide with this object,
so let's add a box collider 2D.
0:43
Now, instead of creating the top
one from scratch,
0:49
we can simply select
this bottom pipe in the hierarchy
0:51
and duplicate
it with Command or Control D.
0:54
Let's rename it to Top Pipe,
0:59
and get the Move tool with the shortcut W.
1:03
Let's move it up a bit
so there's a close enough gap
1:06
for the player to kind of arch through.
1:08
Again,
we can fine tune the sizes and gaps later.
1:13
Now, to keep these objects
connected in a sense,
1:16
we can nest them as children
to another game object.
1:19
Let's do that.
1:22
Now, because of my OCD,
I'm going to move the bottom
1:23
pipe to the bottom, and then I'll hold
shift and select both pipes.
1:26
Let's right click and select create
1:31
empty parent.
1:33
Now they're both sibling game objects.
1:37
Let's name
this parent object pipes, plural.
1:39
Now if we select this parent
and move it on its X axis,
1:43
you'll see they both move along with it,
1:46
staying in their places
relative to each other. Perfect!
1:48
Since we
1:52
don't want gravity and physics
for these, we'll directly
1:53
manipulate its transform's position
in our code to move them.
1:56
And we know that we'll want to manipulate
the transform of this parent object,
2:00
not the individual pipe objects within it,
so that they move together.
2:04
So let's head into our scripts
folder and create
2:08
a new one.
2:11
Let's name it PipesMover.
2:16
Let's attach it to the parent pipes
2:20
object and open it up.
2:25
We want this to continuously move
2:30
left across the screen, so again,
using Update is a perfect approach.
2:32
Also, as I mentioned earlier,
since every game
2:36
object will have a transform component,
we don't need to get a reference to it
2:39
like we had to with the
Rigidbody on our player earlier.
2:43
So let's go straight into Update
and type transform.
2:46
Make sure you use a lowercase t.
2:49
If it's capitalized, it will use it
as the data type, the transform class,
2:51
not a reference
to our transform component.
2:55
Let's type dot,
and the property we want is position.
2:58
The transform's position is of type
Vector3.
3:03
A Vector3 in Unity is a structure
that represents a point or direction
3:06
in 3D space using three float
values for x, y, and z coordinates.
3:10
Remember our transform position in the
inspector window has an x, y, and z value.
3:16
Even though we're working in 2D, sometimes
3:21
we still need to specify things
as a Vector3 like this.
3:23
So let's type equals,
and what we want to do is every frame,
3:27
so every time update is called, assign
this a new Vector3 value,
3:31
bringing it further to the left
slightly each time.
3:35
We do this by typing the new keyword,
followed by Vector3
3:39
and a set of parentheses.
3:43
Within the parentheses,
we need to specify the three
3:46
float values for each coordinate,
but we want it to be relative
3:48
to wherever it currently is
when this frame started.
3:52
So we can type transform.position.x.
3:56
I'm going to copy this,
4:02
add a comma,
4:06
and paste
4:09
this for the y, changing that x to a y,
4:10
and and the same for the Z value.
4:13
This is telling Unity to just get whatever
the current transform positions
4:18
are and just use them again
here, essentially not changing them.
4:22
So as is, this won't affect anything.
4:25
Right now, we only want to move this
on its X axis, so let's get back to that.
4:28
Remember, these are float values,
so we can perform math operations on them.
4:33
And if you remember,
when moving objects to the left in Unity,
4:38
the number gets smaller,
hits zero and goes negative.
4:42
So we know we want to use subtraction
but what do we want to subtract from it?
4:45
Well this is what we get to decide
as how fast we want to move them.
4:50
The more we subtract the faster
they'll move across the screen.
4:54
This sounds like
4:57
another situation where it'll be
nice to have this available in the Unity
4:58
editor to easily adjust,
so let's create a variable for it.
5:02
Up top,
let's create a new serialized field,
5:06
private, float, and call it moveSpeed.
5:11
We can give it a default value of say 10f.
5:15
Now we can say
5:22
transform.position.x minus move speed.
5:23
Let's save this and see what happens.
5:28
Wow, it moved so fast
I didn't even see it!
5:35
This is because of how many frames
are running per second.
5:39
Now we could change this move
speed value to something insanely small.
5:43
But there's another hidden issue arising.
5:47
Everybody's
machine runs at different speeds.
5:50
Let's say I have an older laptop,
5:53
and it's going to run this game
at a wimpy 30 frames per second.
5:55
But my friend has a brand new high-end
desktop.
5:58
It's going to run this game at 150 frames
per second.
6:02
His pipes are going
to move much faster than mine,
6:05
because this update method is getting
called way more times per second.
6:08
Let's go back to our code to fix this.
6:12
After we
6:15
subtract move speed from our current
x position,
6:15
let's also multiply this by Time
with a capital T,
6:18
dot deltaTime.
6:21
Time.deltaTime is the
interval, or time, in seconds
6:25
from the last frame that completed
to the current one in this Update call.
6:29
So you can imagine that
the time in between frames
6:33
is an extremely small fraction
of a number.
6:36
It'll be different on different machines.
6:39
It will even be different per
frame on the same machine, as
6:41
things aren't always super consistent.
6:45
So, due to the order of operations,
this code is going to multiply our move
6:47
speed by this tiny number first,
then subtract it from our X position.
6:52
It'll be slightly different each frame,
but what this will do is keep things
6:57
consistent across different machines
for a smooth experience for everyone.
7:00
Let's save this and try it out.
7:05
Much better. It's still a bit fast
for my taste.
7:12
I'm going to stop this and change
my moveSpeed to 5. Cool.
7:15
Now no need to follow me here
but I'm going to dock my game window
7:23
to the side again.
7:26
If we play again
7:29
and watch the scene window, we'll see that
these pipes never really go away.
7:30
They just keep moving left forever.
7:34
Now with this, eventually,
there are going to be
7:36
a lot of unused pipes
moving along taking up processing power.
7:38
So what we want to do is destroy them
once they're off the screen.
7:43
Let's find a position that will work to do
this.
7:47
Let's select the pipes object, use
the move tool with W, and slide it over.
7:49
I think negative 13 will work great.
7:55
Let's go back to our code.
7:59
So after we move our pipes,
we want to check on every frame
8:02
if our x position is negative 13,
or whatever number you decided on.
8:06
You can also make this
a serialized variable
8:11
and adjust it in the editor,
but I'm not too worried about this one.
8:13
As long as it's off the screen,
it works for me.
8:17
So below our movement code,
let's write a conditional.
8:20
if transform.position.x
We could just put in equals,
8:24
but it's generally a safe practice,
if you're subtracting, to check
8:30
if it's less than or equal to negative 13,
or whatever number you chose.
8:34
Just in case things are moving fast
and something slips
8:38
through the cracks, missing the very frame
it hits our number, we're safe.
8:41
So if this is true,
8:46
we want to destroy with a capital D,
and in the parentheses
8:47
we write game
object, lowercase g, uppercase O.
8:51
With a capital G, again, it's going to
think we're talking about a data type.
8:55
But with a lowercase g,
8:59
this is referencing the game object
that this script is attached to.
9:01
And since our individual pipes
are children
9:05
objects to this object,
those will also be destroyed.
9:07
Let's save and test it out.
9:11
And there it goes,
completely deleted from our scene.
9:21
And don't worry,
if we press stop, they'll come back.
9:24
So we've got our pipes moving.
9:29
But getting our player to fly through one
set of pipes makes for a very fast game.
9:30
So in the next video,
9:35
we'll learn how we can
continuously spawn sets of pipes for
9:36
the player to fly through.
9:39
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