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hello in this video tutorial I'm going to show you how to make the vertical motion and I will

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do it for a kind of platformer game so it's going to be some jumping well we have already made a

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horizontal motion with acceleration and inertia so we start from here and I'm going to explain

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how to jump now and a platform again but former kind of game the cat will be jumping up only when

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on the ground or on a platform so we have to draw some ground and platforms so let's go into the

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backdrop here and let's draw let's say a rectangle filled with some color and that's going to be our

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ground and let's say we draw a platformer line here and let's say another platformer line there

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so let's make this a little thicker

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okay now we got some grounds and platforms so as I was saying the cat is only going to

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jump up if it's on standing on a platform or a ground that means touching the green color so

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we're going to control and use an if touching the color but then instead of using just if touching

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the color I'm going to use the if-else because I want something to happen if it is not touching

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the color right what's going to happen if it's not touching the color that mean it's midway in a

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jump so it will fall down so here I'm going to place what happens when it's falling down and

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here I will place what happens when it can jump so first thing if touching color so the sensing

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touching color pick the right color

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and then so if it is touching the color it will jump and if it is not touching else here it will

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fall down falling down is an accelerated kind of motion because you fall faster and faster the

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higher you fall from the faster you get to the ground so we're going to use the same approach

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as we use for the accelerated horizontal motion so the motion will be accomplished by changing

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the vertical coordinate here so we're going to motion and change the vertical coordinate by as

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it's going to be accelerated this is going to be a number that change so we need a variable we're

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going to variables make a variable that's going to be called the y speed and we're going to change

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the vertical position by the value of this vertical speed and at the beginning it's going to be zero

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so now quite the same as we did with a horizontal acceleration we will use the

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vertical acceleration here for the falling down so we change the vertical speed

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and as it's going down we have to use a negative number here instead of using this minus two I've

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found out that the smaller number works better so we'll use 0.5 so you can change this number

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to make it fall down faster or slower so we have taken account of falling down so let's check it

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so if it's there and if we place this inside our forever and

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from the beginning then if it is not touching it will fall down so it's falling down at an

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accelerating rate if it falls from higher it will go faster if it's falling from lower place it will

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fall now first of all we want the fall to stop when it gets to the ground or to a platform so

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it can stand on top of it so how can we do so well we know when it's touching the color so

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first thing will be to stop the downwards motion we can stop that downwards motion by setting the

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vertical speed to zero so if touching the color it should stop so let's check it so I have to

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hit the green flag and now if it falls now it will stop because if touching green color then

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vertical variable will be zero and now stops now

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it stops there good so we have taken care of the downwards motion the falling now we have to take

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care of the upwards motion the jumping for us to make the cat jump we will use the arrow key

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up arrow key so if

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under sensing key press

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meaning up arrow key press then what then go up but we don't want it to be

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accelerating up so we don't use change the vertical speed we will set a fixed value so it

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jumps up at a fixed speed so we use set instead of change so we will make it go up at some speed

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let's say 10 right so if the arrow keys press the vertical speed will be 10 now when only if

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it is touching the ground or a platform right because we don't want it to be able to fly in

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middle air so now let's check it now I hit the up arrow and it's not going up why because I haven't

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change it here my variable to now if touching color it is speed to zero stop and then I hit

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the right arrow and it goes up like that now when I release it it falls down automatically if I keep

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hitting the arrow it doesn't go anywhere because it is not touching the green color it's in me

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there so this doesn't work so this will only work if touching color if not touching color it just

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falls down and now I can jump on top of the platforms but then there's something which is

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standing on the platforms but there's something which is quite wrong here look if I go up from

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here I'm touching the green and I can go up to the platform I'm going through the platform and

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that's not good so I have to prevent the cat from going through the platform somehow how can I do

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it well one simple way would be to use a different color for the underside of the platform so I'm

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going to use a red color here and draw a rectangle underneath the platform

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like that and then if I touch that color I will make the cat go down like bouncing back

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so I use if

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and I put this inside the same forever here now touching color

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now this other color I will pick it

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then what then something fall down so this is the falling down block so duplicated but

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now if I want to make the bouncing back different from falling down I can just make this faster so

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I can use let's say minus five so let's have a look at it now I move under the platform I go up

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and it will bounce back faster than falling look this is falling and this is bouncing back now you

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have to pick the right angle for you to be able to jump into that

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okay well so let's recollect we are making the upwards motion using change vertical value

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coordinate with a variable speed here vertical speed this is zero at the beginning only if you

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touch in the ground or a platform color then you can make it go up by setting the vertical value

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to 10 if touching color it will make it zero so when it falls down it will stop there and

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if not touching the color it will automatically accelerate downwards now to prevent the cat

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from going through the underside of the platform we use a different color and if

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touching that color we make it fall down even faster than when in midair and what with this

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you can make a jumping kind of game you can of course include more sprites so if you get them

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you can get points you can put some kind of lava floor so if you jump into it you

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you die and so on okay thank you