I have gravity (-9.8, 0). There is a dynamic object that when it hits the right wall, (a static line), about 5% of the time will stick to it. It then ignores the gravity, and nothing I do in the code seems to resolve this.
I’ve tried checking if the object is awake, reseting the gravity, checking to make sure that the event causing the rightward movement has stopped…
Any suggestions on how to fix this?
Hi @robertsonmdavid,
There’s no logical reason why it should be doing this, but we’d have to see some of your code to determine what’s going on. It’s probably a very simple fix… we just don’t know what you’ve programmed.
Best regards,
Brent
I tried to trim it down a bit. I think this is the offending code.
[lua]
local composer = require( “composer” )
local scene = composer.newScene()
– include Corona’s “physics” library
local physics = require “physics”
local surrey=nil
local leftWall
local rightWall
local function applyMovementLoop ()
surrey:applyLinearImpulse(.005,0)
end
function movement (event)
if event.phase == “began” then
moveLoopTimer = timer.performWithDelay( 10, applyMovementLoop, 0 )
elseif event.phase == “ended” or event.phase == “cancelled” then
timer.cancel( moveLoopTimer )
end
return true
end
function scene:create( event )
local sceneGroup = self.view
physics.start()
physics.setGravity( -9.8, 0 )
physics.pause()
surrey= display.newImageRect(sceneGroup, “surrey.png”, 60,75)
surrey.x= halfW
surrey.y=screenH-100
physics.addBody( surrey,“dynamic”, {radius=22, bounce=0, } )
surrey.myName=“surrey”
surrey.isFixedRotation=true
surrey:setLinearVelocity(0,0)
leftWall = display.newLine(sceneGroup,10,0,10, display.contentHeight )
rightWall = display.newLine (sceneGroup,display.contentWidth-10, 0, display.contentWidth-10, display.contentHeight)
–leftWall.alpha=0
–rightWall.alpha=0
physics.addBody (leftWall, “static”, { bounce = 0} )
physics.addBody (rightWall, “static”, { bounce = 0} )
end
function scene:show( event )
local sceneGroup = self.view
local phase = event.phase
if phase == “will” then
elseif phase == “did” then
physics.start()
physics.setGravity(-9.8,0)
surrey:setLinearVelocity(0,0)
surrey.y=screenH-100
Runtime:addEventListener(“touch”, movement)
end
end
[/lua]
Hmmm… can you try changing the walls from “newLine” objects to very thin rectangles (display.newRect())? There have historically been issues when using physics on “line” objects and I generally don’t recommend doing so (there are other potential reasons why not to, as well).
Brent
The thicker the wall the better.
You can also set your object “isBullet” setting to true. *This is processor intensive so use sparingly.
[lua]
object.isBullet = true
[/lua]
That forces the physics engine to check for collisions continuously.
The problem isn’t with the collision detection; it’s doing a good job with this. It’s also registering all of the taps and releases, and calling the appropriate methods at the correct time. The problem is that for some reason gravity stops impacting the object after it hits the wall about 5%of the time. I tried making thick walls, it doesn’t change this. I also tried changing the lines to rectangles using this code:
[lua]leftWall = display.newRect(sceneGroup,10,display.contentHeight/2,1, display.contentHeight )
rightWall = display.newRect(sceneGroup,display.contentWidth-10, display.contentHeight/2, 1, display.contentHeight)[/lua]
I believe I’ve fixed the problem, although i’m not entirely sure why this works. I noticed that touching the screen again unsticks the object from the wall, so I now check on release if the object is touching the right wall. If it is, then I make a touch event happen immediately so that the object doesn’t have a chance to stick, but the user doesn’t notice that anything unusual happened.
Hi @robertsonmdavid,
If I look at your game logic (assuming you haven’t changed it radically since the earlier post), it looks like the user can continue holding down the touch point and the timer will forever run, pushing the object to the right with little impulses. Is that the behavior you want? Because in theory somebody could just keep holding down and the object would just keep getting pushed up against the wall until they let the touch go.
If you want that action to basically stop when the object collides with the wall, you should just cancel the timer upon collision “began”.
Best regards,
Brent
Yeah, that’s the behavior I was looking for. I want the user to be able to stay on the wall if they hold down the press, and come off of the wall again if they release. It does this correctly most of the time, but every once in a while stays on the wall even when the release processes correctly. Though kind of a rough patch, the method I spoke about earlier seemed to fix it.
Hi @robertsonmdavid,
There’s no logical reason why it should be doing this, but we’d have to see some of your code to determine what’s going on. It’s probably a very simple fix… we just don’t know what you’ve programmed.
Best regards,
Brent
I tried to trim it down a bit. I think this is the offending code.
[lua]
local composer = require( “composer” )
local scene = composer.newScene()
– include Corona’s “physics” library
local physics = require “physics”
local surrey=nil
local leftWall
local rightWall
local function applyMovementLoop ()
surrey:applyLinearImpulse(.005,0)
end
function movement (event)
if event.phase == “began” then
moveLoopTimer = timer.performWithDelay( 10, applyMovementLoop, 0 )
elseif event.phase == “ended” or event.phase == “cancelled” then
timer.cancel( moveLoopTimer )
end
return true
end
function scene:create( event )
local sceneGroup = self.view
physics.start()
physics.setGravity( -9.8, 0 )
physics.pause()
surrey= display.newImageRect(sceneGroup, “surrey.png”, 60,75)
surrey.x= halfW
surrey.y=screenH-100
physics.addBody( surrey,“dynamic”, {radius=22, bounce=0, } )
surrey.myName=“surrey”
surrey.isFixedRotation=true
surrey:setLinearVelocity(0,0)
leftWall = display.newLine(sceneGroup,10,0,10, display.contentHeight )
rightWall = display.newLine (sceneGroup,display.contentWidth-10, 0, display.contentWidth-10, display.contentHeight)
–leftWall.alpha=0
–rightWall.alpha=0
physics.addBody (leftWall, “static”, { bounce = 0} )
physics.addBody (rightWall, “static”, { bounce = 0} )
end
function scene:show( event )
local sceneGroup = self.view
local phase = event.phase
if phase == “will” then
elseif phase == “did” then
physics.start()
physics.setGravity(-9.8,0)
surrey:setLinearVelocity(0,0)
surrey.y=screenH-100
Runtime:addEventListener(“touch”, movement)
end
end
[/lua]
Hmmm… can you try changing the walls from “newLine” objects to very thin rectangles (display.newRect())? There have historically been issues when using physics on “line” objects and I generally don’t recommend doing so (there are other potential reasons why not to, as well).
Brent
The thicker the wall the better.
You can also set your object “isBullet” setting to true. *This is processor intensive so use sparingly.
[lua]
object.isBullet = true
[/lua]
That forces the physics engine to check for collisions continuously.
The problem isn’t with the collision detection; it’s doing a good job with this. It’s also registering all of the taps and releases, and calling the appropriate methods at the correct time. The problem is that for some reason gravity stops impacting the object after it hits the wall about 5%of the time. I tried making thick walls, it doesn’t change this. I also tried changing the lines to rectangles using this code:
[lua]leftWall = display.newRect(sceneGroup,10,display.contentHeight/2,1, display.contentHeight )
rightWall = display.newRect(sceneGroup,display.contentWidth-10, display.contentHeight/2, 1, display.contentHeight)[/lua]
I believe I’ve fixed the problem, although i’m not entirely sure why this works. I noticed that touching the screen again unsticks the object from the wall, so I now check on release if the object is touching the right wall. If it is, then I make a touch event happen immediately so that the object doesn’t have a chance to stick, but the user doesn’t notice that anything unusual happened.
Hi @robertsonmdavid,
If I look at your game logic (assuming you haven’t changed it radically since the earlier post), it looks like the user can continue holding down the touch point and the timer will forever run, pushing the object to the right with little impulses. Is that the behavior you want? Because in theory somebody could just keep holding down and the object would just keep getting pushed up against the wall until they let the touch go.
If you want that action to basically stop when the object collides with the wall, you should just cancel the timer upon collision “began”.
Best regards,
Brent
Yeah, that’s the behavior I was looking for. I want the user to be able to stay on the wall if they hold down the press, and come off of the wall again if they release. It does this correctly most of the time, but every once in a while stays on the wall even when the release processes correctly. Though kind of a rough patch, the method I spoke about earlier seemed to fix it.