Intersecting two objects

helloworld2013d · November 24, 2015, 10:36pm

Hello…

I have a red circle.

local redCircle = display.newCircle(0, 0, 30)

and a green circle …

local greenCircle = display.newCircle(1400, 0, 20)

I have a transition to both circles.

transition.to(redCircle, {time=1000, x=1400}) transition.to(greenCircle, {time=100, x=0})

redCircle is going slow from left to right

greenCircle is going fast from right to left

QUESTION

How can I detect at what point the “meet” or “have a collision”

or “intersect”

something like

if redCircle.x + (30) == greenCircle.x + (20) then -- the (30) or (20) is the radius of the circles &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; transition.cancel( ) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; audio.play(sound1) end

As soon as the outer circumference meet they “know” they “crash”

so the function does something

Thanks for all your help

Victor

rob · November 24, 2015, 10:57pm

Perhaps this tutorial will guide you in the right direction.

https://coronalabs.com/blog/2013/07/23/tutorial-non-physics-collision-detection/

Rob

InfiSnyp · November 24, 2015, 11:03pm

Are you using physics?

–SonicX278

helloworld2013d · November 25, 2015, 1:48am

Hi Rob…

I have this function

&nbsp;&nbsp;&nbsp; local obj1 = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; obj1.x = 100 &nbsp;&nbsp;&nbsp; obj1.y = 100 &nbsp;&nbsp;&nbsp; obj1:setFillColor(1, 0, 1) &nbsp;&nbsp;&nbsp; transition.to(obj1, {time=1000, x=1200}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; local obj2 = display.newCircle(0, 0, 50) &nbsp;&nbsp;&nbsp; obj2.x = 1200 &nbsp;&nbsp;&nbsp; obj2.y = 100 &nbsp;&nbsp;&nbsp; obj2:setFillColor(1, 0, 0) &nbsp;&nbsp;&nbsp; transition.to(obj2, {time=5000, x=100}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; -- Circle-based collision detection local function hasCollidedCircle( obj1, obj2 ) &nbsp;&nbsp;&nbsp; if ( obj1 == nil ) then&nbsp; -- Make sure the first object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; if ( obj2 == nil ) then&nbsp; -- Make sure the other object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; local dx = obj1.x - obj2.x &nbsp;&nbsp;&nbsp; local dy = obj1.y - obj2.y &nbsp;&nbsp;&nbsp; local distance = math.sqrt( dx\*dx + dy\*dy ) &nbsp;&nbsp;&nbsp; local objectSize = (obj2.contentWidth/2) + (obj1.contentWidth/2) &nbsp;&nbsp;&nbsp; if ( distance \< objectSize ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return true &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; return false end hasCollidedCircle( obj1, obj2 )

But how do I detect they are “touching”?

The article is long…

but really good, I think this is what I am looking for

and I am not using physics

I will have just circles moving around

in a pre-defined path. so no physics

I need the famous

if obj1 is touching obj2 then …

where can I download this sample App?

rob · November 25, 2015, 2:59am

that function returns either true or falls if they are intersecting or not. So you have to use it in an “if” test:

if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching else &nbsp;&nbsp;&nbsp; -- do stuff when they are not touching end

helloworld2013d · December 1, 2015, 9:17pm

Hi Rob…

I look at the if … you gave mebut I don’t know

where should I put it

all this is inside the create scene

&nbsp;&nbsp;&nbsp; -- fondo &nbsp;&nbsp;&nbsp; bg = display.newImageRect( sceneGroup, "images/bg.jpg", 1500, 900 ) &nbsp;&nbsp;&nbsp; bg.x = display.contentCenterX &nbsp;&nbsp;&nbsp; bg.y = display.contentCenterY &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; obj1 = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; obj1.x = 100 &nbsp;&nbsp;&nbsp; obj1.y = 100 &nbsp;&nbsp;&nbsp; obj1:setFillColor(1, 0, 1) &nbsp;&nbsp;&nbsp; transition.to(obj1, {time=4000, x=1200}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; obj2 = display.newCircle(0, 0, 50) &nbsp;&nbsp;&nbsp; obj2.x = 1200 &nbsp;&nbsp;&nbsp; obj2.y = 100 &nbsp;&nbsp;&nbsp; obj2:setFillColor(1, 0, 0) &nbsp;&nbsp;&nbsp; transition.to(obj2, {time=5000, x=100}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; bomb = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; bomb.x = 700 &nbsp;&nbsp;&nbsp; bomb.y = 600 &nbsp;&nbsp;&nbsp; bomb:setFillColor(0, 1, 0) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; -- Circle-based collision detection local function hasCollidedCircle( obj1, obj2 ) &nbsp;&nbsp;&nbsp; if ( obj1 == nil ) then&nbsp; -- Make sure the first object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; if ( obj2 == nil ) then&nbsp; -- Make sure the other object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; local dx = obj1.x - obj2.x &nbsp;&nbsp;&nbsp; local dy = obj1.y - obj2.y &nbsp;&nbsp;&nbsp; local distance = math.sqrt( dx\*dx + dy\*dy ) &nbsp;&nbsp;&nbsp; local objectSize = (obj2.contentWidth/2) + (obj1.contentWidth/2) &nbsp;&nbsp;&nbsp; if ( distance \< objectSize ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return true &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; return false end hasCollidedCircle( obj1, obj2 ) local function hope() &nbsp;&nbsp;&nbsp; if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 3 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 3 &nbsp;&nbsp; &nbsp;else &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 1 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 1 &nbsp;&nbsp; &nbsp;end end hope()

I put it inside a function and I call both functions

hope( )

hasCollidedCircle( obj1, obj2 )

I put it under – hasCollidedCircle( obj1, obj2 ) function and nothing

I am expecting the little circle “bomb”

to get big as soon as both circles touch

and nothing

Thanks for your time

Victor

rob · December 3, 2015, 1:48am

You would probably need to setup a Runtime “enterFrame” listener that fires every 1/30th or 1/60th of a second. The function that gets called would be where you would do this check.

Rob

helloworld2013d · December 3, 2015, 4:53pm

Thank you very much Rob

it works!!! now…

great!!!

I added the Runtime

local function hope( ) &nbsp;&nbsp;&nbsp; if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 3 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 3 &nbsp;&nbsp; &nbsp;else &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 1 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 1 &nbsp;&nbsp; &nbsp;end end Runtime:addEventListener("enterFrame", hope )

And now works fine.

Thanks

rob · November 24, 2015, 10:57pm

Perhaps this tutorial will guide you in the right direction.

https://coronalabs.com/blog/2013/07/23/tutorial-non-physics-collision-detection/

Rob

InfiSnyp · November 24, 2015, 11:03pm

Are you using physics?

–SonicX278

helloworld2013d · November 25, 2015, 1:48am

Hi Rob…

I have this function

&nbsp;&nbsp;&nbsp; local obj1 = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; obj1.x = 100 &nbsp;&nbsp;&nbsp; obj1.y = 100 &nbsp;&nbsp;&nbsp; obj1:setFillColor(1, 0, 1) &nbsp;&nbsp;&nbsp; transition.to(obj1, {time=1000, x=1200}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; local obj2 = display.newCircle(0, 0, 50) &nbsp;&nbsp;&nbsp; obj2.x = 1200 &nbsp;&nbsp;&nbsp; obj2.y = 100 &nbsp;&nbsp;&nbsp; obj2:setFillColor(1, 0, 0) &nbsp;&nbsp;&nbsp; transition.to(obj2, {time=5000, x=100}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; -- Circle-based collision detection local function hasCollidedCircle( obj1, obj2 ) &nbsp;&nbsp;&nbsp; if ( obj1 == nil ) then&nbsp; -- Make sure the first object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; if ( obj2 == nil ) then&nbsp; -- Make sure the other object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; local dx = obj1.x - obj2.x &nbsp;&nbsp;&nbsp; local dy = obj1.y - obj2.y &nbsp;&nbsp;&nbsp; local distance = math.sqrt( dx\*dx + dy\*dy ) &nbsp;&nbsp;&nbsp; local objectSize = (obj2.contentWidth/2) + (obj1.contentWidth/2) &nbsp;&nbsp;&nbsp; if ( distance \< objectSize ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return true &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; return false end hasCollidedCircle( obj1, obj2 )

But how do I detect they are “touching”?

The article is long…

but really good, I think this is what I am looking for

and I am not using physics

I will have just circles moving around

in a pre-defined path. so no physics

I need the famous

if obj1 is touching obj2 then …

where can I download this sample App?

rob · November 25, 2015, 2:59am

that function returns either true or falls if they are intersecting or not. So you have to use it in an “if” test:

if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching else &nbsp;&nbsp;&nbsp; -- do stuff when they are not touching end

helloworld2013d · December 1, 2015, 9:17pm

Hi Rob…

I look at the if … you gave mebut I don’t know

where should I put it

all this is inside the create scene

&nbsp;&nbsp;&nbsp; -- fondo &nbsp;&nbsp;&nbsp; bg = display.newImageRect( sceneGroup, "images/bg.jpg", 1500, 900 ) &nbsp;&nbsp;&nbsp; bg.x = display.contentCenterX &nbsp;&nbsp;&nbsp; bg.y = display.contentCenterY &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; obj1 = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; obj1.x = 100 &nbsp;&nbsp;&nbsp; obj1.y = 100 &nbsp;&nbsp;&nbsp; obj1:setFillColor(1, 0, 1) &nbsp;&nbsp;&nbsp; transition.to(obj1, {time=4000, x=1200}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; obj2 = display.newCircle(0, 0, 50) &nbsp;&nbsp;&nbsp; obj2.x = 1200 &nbsp;&nbsp;&nbsp; obj2.y = 100 &nbsp;&nbsp;&nbsp; obj2:setFillColor(1, 0, 0) &nbsp;&nbsp;&nbsp; transition.to(obj2, {time=5000, x=100}) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; bomb = display.newCircle(0, 0, 30) &nbsp;&nbsp;&nbsp; bomb.x = 700 &nbsp;&nbsp;&nbsp; bomb.y = 600 &nbsp;&nbsp;&nbsp; bomb:setFillColor(0, 1, 0) &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; -- Circle-based collision detection local function hasCollidedCircle( obj1, obj2 ) &nbsp;&nbsp;&nbsp; if ( obj1 == nil ) then&nbsp; -- Make sure the first object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; if ( obj2 == nil ) then&nbsp; -- Make sure the other object exists &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return false &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; local dx = obj1.x - obj2.x &nbsp;&nbsp;&nbsp; local dy = obj1.y - obj2.y &nbsp;&nbsp;&nbsp; local distance = math.sqrt( dx\*dx + dy\*dy ) &nbsp;&nbsp;&nbsp; local objectSize = (obj2.contentWidth/2) + (obj1.contentWidth/2) &nbsp;&nbsp;&nbsp; if ( distance \< objectSize ) then &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return true &nbsp;&nbsp;&nbsp; end &nbsp;&nbsp;&nbsp; return false end hasCollidedCircle( obj1, obj2 ) local function hope() &nbsp;&nbsp;&nbsp; if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 3 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 3 &nbsp;&nbsp; &nbsp;else &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 1 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 1 &nbsp;&nbsp; &nbsp;end end hope()

I put it inside a function and I call both functions

hope( )

hasCollidedCircle( obj1, obj2 )

I put it under – hasCollidedCircle( obj1, obj2 ) function and nothing

I am expecting the little circle “bomb”

to get big as soon as both circles touch

and nothing

Thanks for your time

Victor

rob · December 3, 2015, 1:48am

You would probably need to setup a Runtime “enterFrame” listener that fires every 1/30th or 1/60th of a second. The function that gets called would be where you would do this check.

Rob

helloworld2013d · December 3, 2015, 4:53pm

Thank you very much Rob

it works!!! now…

great!!!

I added the Runtime

local function hope( ) &nbsp;&nbsp;&nbsp; if hasCollidedCircle( obj1, obj2 ) then &nbsp;&nbsp;&nbsp; -- do the stuff when they are touching &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 3 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 3 &nbsp;&nbsp; &nbsp;else &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.xScale = 1 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;bomb.yScale = 1 &nbsp;&nbsp; &nbsp;end end Runtime:addEventListener("enterFrame", hope )

And now works fine.

Thanks