Is there a way to detect when the objects in the drag me demo collide? I tried setting up a global runtime collision detector and wasn’t able to get it working.
http://developer.anscamobile.com/content/drag-me [import]uid: 14218 topic_id: 27327 reply_id: 327327[/import]
Are you talking about proper collision (using physics) or comparing coords without physics? [import]uid: 52491 topic_id: 27327 reply_id: 111040[/import]
Here’s two solutions. The first is manually calculating whether the boxes are overlapping and the second requires adding the physics engine to detect collisions. You’ll notice that in this example only the start and end of the physics collisions are displayed, but you can check the API documentation to see that there are other types.
– THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
– INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
– PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
– FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
– OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
– DEALINGS IN THE SOFTWARE.
– Demonstrates how to use create draggable objects. Also shows how to move
– an object to the top.
local physics = require(“physics”)
physics.start()
physics.setGravity(0,0)
physics.setDrawMode(“hybrid”)
local arguments =
{
{ name=“one”, x=50, y=10, w=100, h=100, r=10, red=255, green=0, blue=128 },
{ name=“two”, x=10, y=200, w=100, h=100, r=10, red=0, green=128, blue=255 },
{ name=“three”, x=90, y=350, w=100, h=100, r=10, red=255, green=255, blue=0 }
}
– manual checking of collisions
local stage = display.getCurrentStage()
local function checkCollisions()
for i=1, stage.numChildren do
for c=1, stage.numChildren do
if (i ~= c) then
local a, b = stage[i], stage[c]
local hw = b.width
if (a.x>b.x-hw and a.x<b.x and a.y>b.y-hw and a.y<b.y then> print('MANUAL: ‘…a.name…’ collides with '…b.name)
end
end
end
end
end
local function printTouch( event )
if event.target then
local bounds = event.target.stageBounds
print( “event(” … event.phase … “) (”…event.x…","…event.y…") bounds: “…bounds.xMin…”,"…bounds.yMin…","…bounds.xMax…","…bounds.yMax )
checkCollisions()
end
end
local function onTouch( event )
local t = event.target
– Print info about the event. For actual production code, you should
– not call this function because it wastes CPU resources.
printTouch(event)
local phase = event.phase
if “began” == phase then
– Make target the top-most object
local parent = t.parent
parent:insert( t )
display.getCurrentStage():setFocus( t )
– Spurious events can be sent to the target, e.g. the user presses
– elsewhere on the screen and then moves the finger over the target.
– To prevent this, we add this flag. Only when it’s true will “move”
– events be sent to the target.
t.isFocus = true
– Store initial position
t.x0 = event.x - t.x
t.y0 = event.y - t.y
elseif t.isFocus then
if “moved” == phase then
– Make object move (we subtract t.x0,t.y0 so that moves are
– relative to initial grab point, rather than object “snapping”).
t.x = event.x - t.x0
t.y = event.y - t.y0
elseif “ended” == phase or “cancelled” == phase then
display.getCurrentStage():setFocus( nil )
t.isFocus = false
end
end
– Important to return true. This tells the system that the event
– should not be propagated to listeners of any objects underneath.
return true
end
local function physicsCollision( event )
print('PHYSICS: ‘…event.target.name…’ collided with '…event.other.name)
end
– Iterate through arguments array and create rounded rects (vector objects) for each item
for _,item in ipairs( arguments ) do
local button = display.newRoundedRect( item.x, item.y, item.w, item.h, item.r )
button:setFillColor( item.red, item.green, item.blue )
button.strokeWidth = 6
button:setStrokeColor( 200,200,200,255 )
– physics collision detection
button.name = item.name
physics.addBody( button, “dynamic” )
button.isSensor=true
button:addEventListener( “collision”, physicsCollision )
– Make the button instance respond to touch events
button:addEventListener( “touch”, onTouch )
end
– listener used by Runtime object. This gets called if no other display object
– intercepts the event.
local function printTouch2( event )
print( “event(” … event.phase … “) (”…event.x…","…event.y…")" )
return true
end
Runtime:addEventListener( “touch”, printTouch2 )[/lua]
[import]uid: 8271 topic_id: 27327 reply_id: 111042[/import] </b.y></b.x>
Thank you Peach and horacebury. I want to use physics because there’s some cool things I can do with physics and this points me in the right direction. Thank you. [import]uid: 14218 topic_id: 27327 reply_id: 111068[/import]
horacebury seems to be super productive lately. My suspicion is his coffee addiction has kicked up a notch 
Awesome stuff - look forward to seeing what you do with it 
[import]uid: 52491 topic_id: 27327 reply_id: 111108[/import]
Thank you - it has.
To be honest though, I really get a kick out of putting up useful, working and helpful samples. Lua is such a nice language to use and in my breaks I can get helpful bits into the community. I hope that lots of people feel like that too. I suspect they do, from looking at the great activity on these forums. [import]uid: 8271 topic_id: 27327 reply_id: 111118[/import]