Hello to everyone!
I’m coding a physics game, and i have found a frustrating behavior when use the startDrag function from the “Drag Platforms” sample app source code.
I have recorded a video to show exactly what happens when you touch a body without moving it (sorry for my poor english):
http://www.youtube.com/watch?v=ADp-HTWlGKI
When i touch (without move) a draggable object, it falls down on the scenario, but comes back to the initial position. But the more times you touch (without move) the same object, the more far falls down, until it falls out of the platform.
The thing is, this only happen between dynamic objects and static objects (for example, between a box tha i’m touching, and the ground or a platform). If i have a dynamic object above another dynamic one, it doesn’t fall. And it’s frustrating because after a few touches, the object just disappear from the scenario.
I was thinking that the problem is that the body it’s already in collision when the type is set back to dynamic, so i have made a small change in the code to avoid this, setting the bodytype as “dynamic” OUT of the collision function, with no success.
When the collision ends, or is cancelled, i set the body type to “static”, and after 500 miliseconds, i turn back the body to dynamic. And nothing changes, the behavior stills happenig and the object stills falling down. It’s like if the body doesn’t collides whith the ground.
This is the code of the complete “startDrag” function i’m using, plus the additional function i have created to delay the transform of the body type from “kinematic” to “dynamic” (introducing the intermediate step “static”):
-- Function that turns the body-type of all the draggable objects to "dynamic"
local function convierteDinamico ()
caja.bodyType = "dynamic"
tablon.bodyType = "dynamic"
end
--\> STARTDRAG
--\>
local function startDrag( event )
local t = event.target
local phase = event.phase
if "began" == phase then
audio.play(sonido\_pulsar)
display.getCurrentStage():setFocus( t )
t.isFocus = true
-- Store initial position
t.x0 = event.x - t.x
t.y0 = event.y - t.y
-- Prints the "x" and "y" values of the body, just for debug
print( "t.x0 =", t.x0)
print( "t.y0 =", t.y0)
print( "t.x: ", t.x )
print( "t.y: ", t.y )
print( "event.x: ", event.x )
print( "event.y: ", event.y )
-- Make body type temporarily "kinematic" (to avoid gravitional forces)
event.target.bodyType = "kinematic"
physics.setGravity (0, 0)
event.target:scale( 1.3, 1.3 )
event.target.alpha = 0.8
-- Stop current motion, if any
event.target:setLinearVelocity( 0, 0 )
event.target.angularVelocity = 0
elseif t.isFocus then
if "moved" == phase then
if (event.x == t.x0) or (event.y == t.y0) then
t.x = event.x
t.y = event.y
print( "Primer IF t.x: ", t.x )
print( "Primer IF t.y: ", t.y )
print( "Primer IF t.x: ", event.x )
print( "Primer IF t.x: ", event.y )
else
t.x = event.x - t.x0
t.y = event.y - t.y0
print( "t.x0 =", t.x0)
print( "t.y0 =", t.y0)
print( "Else t.x: ", t.x )
print( "Else t.y: ", t.y )
print( "Else event.x: ", event.x )
print( "Else event.y: ", event.y )
end
elseif "ended" == phase or "cancelled" == phase then
display.getCurrentStage():setFocus( nil )
t.isFocus = false
audio.play(sonido\_soltar)
physics.setGravity (0, 19.8)
event.target.bodyType = "static"
event.target:scale( 0.77, 0.77 )
event.target.alpha = 1.0
timer.performWithDelay(500, convierteDinamico, 1 )
-- Switch body type back to "dynamic", unless we've marked this sprite as a platform
-- if ( not event.target.isPlatform ) then
-- event.target.bodyType = "dynamic"
-- end
end
end
-- Stop further propagation of touch event!
return true
end I am trying absolutely all the combinations of body-types, changing physics engine options, and i’m going completely crazy. 
What i’m doing wrong? [import]uid: 14235 topic_id: 7434 reply_id: 307434[/import]