How to add collision and dragging to randomly displayed objects?

Getting Started Newbie Questions
#1

Hi. I want to add collision as well as make the randomly displayed objects dragable.The objects fall from the top.Here’s how I tried but not working.I haven’t added code to drag randomly displayed objects here but I have tried.Only objects are being displayed.Help me with this issue.Thanks.

local function box()

rand = math.random( 10 )

if (rand < 5) then 

local crate1 = display.newImageRect( “but3.jpg”, 100, 100 )

crate1.x, crate1.y = 53, -80

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate3 = display.newImageRect( “crate.png”, 100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

elseif(rand < 9 ) then 

local crate1 = display.newImageRect( “but3.jpg”, 100, 100 );

crate1.x, crate1.y = 53, -80

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate2 = display.newImageRect( “crate.png”, 100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

else

local crate2 = display.newImageRect( “crate.png”, 100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

local crate3 = display.newImageRect( “crate.png”, 100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

end

end

local function gameLoop()

box()

 end

 gameLoopTimer = timer.performWithDelay( 3000, gameLoop, 0 )

 local platform = display.newRect( 0, 0, 60, 30 )

platform.surfaceType = “superbounce”

platform.x, platform.y = display.contentCenterX, display.contentCenterY+80

physics.addBody( platform, “static”, { bounce=0.0, friction=0.3 } )

platform.myName = “platform”

–Code to drag Platform

 local function dragplatform( event )

    local platform = event.target

    local phase = event.phase

    if ( “began” == phase ) then

        – Set touch focus on the platform

        display.currentStage:setFocus( platform )

        – Store initial offset position

        platform.touchOffsetX = event.x - platform.x

         platform.touchOffsetY = event.y - platform.y

    elseif ( “moved” == phase ) then

        – Move the platform to the new touch position

        platform.x = event.x - platform.touchOffsetX

        platform.y = event.y - platform.touchOffsetY

    elseif ( “ended” == phase or “cancelled” == phase ) then

        – Release touch focus on the platform

        display.currentStage:setFocus( nil )

    end

    return true  – Prevents touch propagation to underlying objects

end

platform:addEventListener( “touch”, dragplatform )

–HERE IS THE CODE FOR COLLISION.

local function onCollision( event )

if ( event.phase == “began” ) then

local obj1 = event.object1

local obj2 = event.object2

if  ( obj1.myName == “platform” and obj2.myName == “crate1” ) 

then

display.remove( obj1 )

           

end 

end

#2

local function box()

rand = math.random( 10 )

if (rand < 5) then 

local crate1 = display.newRect( 0,0,100, 100 );

crate1.x, crate1.y = 53, -80

crate

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate3 = display.newRect( 0,0,100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

 crate1:addEventListener(“touch”,dragplatform)

crate3:addEventListener(“touch”,dragplatform)

elseif(rand < 9 ) then 

local crate1 = display.newRect( 0,0,100, 100 );

crate1.x, crate1.y = 53, -80

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate2 = display.newRect( 0,0,100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1:addEventListener(“touch”,dragplatform)

crate2:addEventListener(“touch”,dragplatform)

else

local crate2 = display.newRect( 0,0,100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate2:addEventListener(“touch”,dragplatform)

local crate3 = display.newRect( 0,0,100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

crate3:addEventListener(“touch”,dragplatform)

end

end

replace this code for dragging falling objects 

add this code for collision

Runtime:addEventListener(“collision”, onCollision

set myName to each crate object and check for collision in onCollision function…

#3

First of all use code formating. It is hard to read your code.

What does it mean it is not working? 

  1. I think you need forward declaration.

    – top of file local crate1 local crate2

Read about local and global variable https://docs.coronalabs.com/daily/guide/start/introLua/index.html#variables

  1. I don’t see physics.start(). You need it to everything work. To how  setup physics engine you can read https://docs.coronalabs.com/daily/guide/physics/physicsSetup/index.html

  2. You need instruction below  for handle global  collision

    Runtime:addEventListener( “collision”, onCollision)

Read about collision handling https://docs.coronalabs.com/daily/guide/physics/collisionDetection/index.html#handling

  1. One physics.setGravity( 0, 1) is enough. Put it on begin of function or file.

EDIT : Some useful links about dragging objects

https://coronalabs.com/blog/2011/09/24/tutorial-how-to-drag-objects/

https://forums.coronalabs.com/topic/35265-drag-object-within-bounds/

http://stackoverflow.com/questions/21755916/corona-lua-dragging-object-without-physics

Hope this help :slight_smile:

#4

local function box()

rand = math.random( 10 )

if (rand < 5) then 

local crate1 = display.newRect( 0,0,100, 100 );

crate1.x, crate1.y = 53, -80

crate

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate3 = display.newRect( 0,0,100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

 crate1:addEventListener(“touch”,dragplatform)

crate3:addEventListener(“touch”,dragplatform)

elseif(rand < 9 ) then 

local crate1 = display.newRect( 0,0,100, 100 );

crate1.x, crate1.y = 53, -80

physics.addBody( crate1, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1.myName = “crate1”

local crate2 = display.newRect( 0,0,100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate1:addEventListener(“touch”,dragplatform)

crate2:addEventListener(“touch”,dragplatform)

else

local crate2 = display.newRect( 0,0,100, 100 );

crate2.x, crate2.y = 160, -80

physics.addBody( crate2, { density=0, friction=0.3, bounce=0 } )

physics.setGravity( 0, 1)

crate2:addEventListener(“touch”,dragplatform)

local crate3 = display.newRect( 0,0,100, 100 );

crate3.x, crate3.y = 267, -80

physics.addBody( crate3, { density=0, friction=0, bounce=0 } )

physics.setGravity( 0, 1)

crate3:addEventListener(“touch”,dragplatform)

end

end

replace this code for dragging falling objects 

add this code for collision

Runtime:addEventListener(“collision”, onCollision

set myName to each crate object and check for collision in onCollision function…

#5

First of all use code formating. It is hard to read your code.

What does it mean it is not working? 

  1. I think you need forward declaration.

    – top of file local crate1 local crate2

Read about local and global variable https://docs.coronalabs.com/daily/guide/start/introLua/index.html#variables

  1. I don’t see physics.start(). You need it to everything work. To how  setup physics engine you can read https://docs.coronalabs.com/daily/guide/physics/physicsSetup/index.html

  2. You need instruction below  for handle global  collision

    Runtime:addEventListener( “collision”, onCollision)

Read about collision handling https://docs.coronalabs.com/daily/guide/physics/collisionDetection/index.html#handling

  1. One physics.setGravity( 0, 1) is enough. Put it on begin of function or file.

EDIT : Some useful links about dragging objects

https://coronalabs.com/blog/2011/09/24/tutorial-how-to-drag-objects/

https://forums.coronalabs.com/topic/35265-drag-object-within-bounds/

http://stackoverflow.com/questions/21755916/corona-lua-dragging-object-without-physics

Hope this help :slight_smile: