How can i make a Player that Jump Up and Falls Down

[Pigzo]

How can i make a Player that Jumps Up and Falls Down? I Haven't Any Idea :/ the Key for Jumping must be Space :s

[tentus]

This tutorial might get you started in the right direction, without handing you the answer on a silver platter.

[veethree]

I'll break it down for you.

First you need a player that has the following, An X position, A Y position and a Y velocity. I'd suggest setting up a table called player and putting the stuff into it like such:

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player = {
	x = 0,
	y = 0,
	yVel = 0
	}

Then you would need a gravity variable. I usually set it to something around 800 to 1200. Next step would be making the player be affected by the gravity. The way that would work is quite simple. In love.update you would increase the players yVel by the gravity value each frame, Then set the player y position to whatever it is at the time + the yVel.

Something like this:

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function love.update(dt)
	player.yVel = player.yVel + gravity * dt
	player.y = player.y + player.yVel * dt
end

Now with that the player would just fall off the screen, then keep falling. I'm assuming you have some form of a ground, So you would want to write a function that checks if the player is on the ground or not. I'm not gonna get into that because the function would differ depending on how your game is set up. Main thing is, If the player is on the ground the function returns true, otherwise it returns false.

So now you'd have to check if the function returns true before the whole gravity thing above. Something like this:

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function love.update(dt)
	if not onGround() then --if the onGround function returns false
		player.yVel = player.yVel + gravity * dt
		player.y = player.y + player.yVel * dt
	end
end

Now you would have to stop the player somehow when he does touch the ground, So you add an else statement, and in it you set the yVel to 0 which stops the player. something like this:

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function love.update(dt)
	if not onGround() then --if the onGround function returns false
		player.yVel = player.yVel + gravity * dt
		player.y = player.y + player.yVel * dt
	else
		player.yVel = 0
	end
end

Now you have the most basic form of physics. For the jumping all you do is set the yVel to some negative value, How high said value is depends on the strength of the gravity and how high you want the player to jump.
Something like this:

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function love.keypressed(key)
	if key == " " then --Checks if the space key was pressed
		player.yVel = -500
	end
end

This would still be incomplete because the player can jump while in mid air, That can be fixed with a simple boolean. Hope this helps.

Note that this code is completely untested. There may be errors in it.

[Pigzo]

Umm I Didn't Understand Anything :/

[veethree]

Umm I Didn't Understand Anything :/

Then i'd suggest trying something simpler first Check out some of the tutorials on the wiki.

[Pigzo]

Okay

[counterman2026]

help!, it says that there is an error to perform on global 'gravity'(a nil value)

[AlexCalv]

help!, it says that there is an error to perform on global 'gravity'(a nil value)

You need to define the variable gravity.

[counterman2026]

how do i do that?

would i do something like this?

gravity = {}

gravity = 10

[AlexCalv]

The simplest way would be to just put it into love.load.

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function love.load()
     gravity = [[Whatever works for your game]]
end