Jump with 0 gravity?

Solar2D General Questions/Discussion
#1

I am using simi top camera where the whole screen is the ground for player to walk so i had to set the gravity to 0 otherwise my player would fall of the screen (or i am doing it wrong?). Now how do i make my character to jump?

Thanks in advance :slight_smile:

#2

Let me re-frame my question…

How do you perform jumps in situations when the whole background is a ground on which your player stands (thus you had to set gravity 0 to prevent your character from falling off the screen)?

Somebody please help!

#3

You can manually transition your sprite to the new position. 

Something like: 

local player = create\_player () player.x, player.y = 100, 100 -- make a jump local JUMP\_TIME = 500 transition.to ( player, { time = JUMP\_TIME, x = player.x + 100 ) transition.to ( player, { time = JUMP\_TIME / 2, y = player.y - 50, transition = easing.outQuad, onComplete = function () transition.to ( player, { time = JUMP\_TIME / 2, y = player.y + 50, transition = easing.inQuad ) end })

Here, by joining 2 transitions at the same time (transition over x is linear, over y isn’t, so it gives you an illusion of parabolic movement - just like a jump forward in a constant gravity field) you get a jumping character without using physics. By modifying the x and y movement (100 and 50 here) you get different jumps. 

#4

I heard the transitions don’t perform physics and i need physics +  collision detection :frowning:

Any workarounds?

#5

Well, my guess is you can manually detect collisions (in some code you run every frame), checking the player’s object bounding rect vs other objects in his vicinity… 

#6

Hi @coolromin,

Just to clarify, collisions will trigger during a transition. However, the transition will continue to “fight” against any opposing physical force caused by the collision (like a bounce off in the other direction), so you’d need to cancel the transition at that point to prevent weird behavior.

Best regards,

Brent

#7

There is no workaround to use normal physics to jump the player??? :0

#8

Well, one solution would be to use normal gravity, but then set your “zero gravity” objects to have a gravity scale of 0. This way, they would float in air, while the player would jump and be affected by gravity as normal.

http://docs.coronalabs.com/api/type/Body/gravityScale.html

Brent

#9

Finally seems like a working solution… But i am very new to corona and so little confused with the solution you provided.

Can you please show me a sample code on how to implement it? Thanks in advance!

#10

I set the gravityScale to 1 and applied linear velocity, The player jumps and falls down but keeps falling down so how do i stop him at same position it was before?

Thanks Again!

#11

I think you’ll need to place a static block at the bottom of the screen.

Have you tried something like this?

[lua]
local bottom = display.newRect( 0, 0, display.contentWidth, 100 )

bottom.x = 0

bottom.y = display.contentHeight + ( bottom.height * .5 )

physics.addBody( bottom, “static” )
[/lua]

#12

Let me re-frame my question…

How do you perform jumps in situations when the whole background is a ground on which your player stands (thus you had to set gravity 0 to prevent your character from falling off the screen)?

Somebody please help!

#13

You can manually transition your sprite to the new position. 

Something like: 

local player = create\_player () player.x, player.y = 100, 100 -- make a jump local JUMP\_TIME = 500 transition.to ( player, { time = JUMP\_TIME, x = player.x + 100 ) transition.to ( player, { time = JUMP\_TIME / 2, y = player.y - 50, transition = easing.outQuad, onComplete = function () transition.to ( player, { time = JUMP\_TIME / 2, y = player.y + 50, transition = easing.inQuad ) end })

Here, by joining 2 transitions at the same time (transition over x is linear, over y isn’t, so it gives you an illusion of parabolic movement - just like a jump forward in a constant gravity field) you get a jumping character without using physics. By modifying the x and y movement (100 and 50 here) you get different jumps. 

#14

I heard the transitions don’t perform physics and i need physics +  collision detection :frowning:

Any workarounds?

#15

Well, my guess is you can manually detect collisions (in some code you run every frame), checking the player’s object bounding rect vs other objects in his vicinity… 

#16

Hi @coolromin,

Just to clarify, collisions will trigger during a transition. However, the transition will continue to “fight” against any opposing physical force caused by the collision (like a bounce off in the other direction), so you’d need to cancel the transition at that point to prevent weird behavior.

Best regards,

Brent

#17

There is no workaround to use normal physics to jump the player??? :0

#18

Well, one solution would be to use normal gravity, but then set your “zero gravity” objects to have a gravity scale of 0. This way, they would float in air, while the player would jump and be affected by gravity as normal.

http://docs.coronalabs.com/api/type/Body/gravityScale.html

Brent

#19

Finally seems like a working solution… But i am very new to corona and so little confused with the solution you provided.

Can you please show me a sample code on how to implement it? Thanks in advance!

#20

I set the gravityScale to 1 and applied linear velocity, The player jumps and falls down but keeps falling down so how do i stop him at same position it was before?

Thanks Again!