Does "delta = false" in a transition work over a Display Group?

Solar2D General Questions/Discussion
#1

Hi,

I was working on a zoom in function over a special part in my game. This part is a display group and I want it to zoom in and set the positions to the middle of the screen but I seem to have some problems.

If you look at this code:

local bool = false local x = display.contentWidth \* 0.5 local y = display.contentHeight \* 0.5 local rect0 = display.newRect( 50, 50, 50, 50) transition.to(rect0, { x = 200, y = y, delta = bool}) local rect1 = display.newRect( 50, 110, 50, 50) transition.to(rect1, { x = 200, y = y, delta = bool}) local rect2 = display.newRect( 50, 170, 50, 50) local rect3 = display.newRect( 50, 230, 50, 50) local dg = display.newGroup() dg:insert( rect2 ) dg:insert( rect3 ) transition.to(dg, { x = 200, y = y, delta = bool}) print(dg.height, dg.width)

The expected value is the the two “loose” rectangles goes to the set position (which they do) and that the dg also go to that position.

Is this a bug or doesn’t delta work on a display group or am I missing something?

Best regards,

Tomas

#2

Can someone comment on this?

Best regards,

Tomas

#3

delta = false would mean that the values provided to the transition are absolute parameters.  So the origin of the display group (which defaults to 0, 0) will end up at x = 200, y = display.contentHeight * 0.5.  If delta is true, in this case, it will still end up at x = 200 and y = display.contentHeight * 0.5 since delta means to add the right hand side of the existing value of x and y.  Since the x and y start at 0, it works out the same.

Rob

#4

Basically I have two display groups that I want when being touched to go into the middle (let’s say display.contentWidht * 0.5 and display.contentHeight * 0.5). One is in the upper left corner and the other is in the bottom left corner.

It doesn’t matter what I change the delta to in this statement, both the display groups go straight down:

Does not work as expected! Works as if delta was set to true.

local x = display.contentWidth \* 0.5 local y = display.contentHeight \* 0.5 local rect2 = display.newRect( 50, 0, 50, 50) local rect3 = display.newRect( 50, 0, 50, 50) local dg = display.newGroup() dg:insert( rect2 ) dg:insert( rect3 ) transition.to(dg, { x = 200, y = y, delta = false}) local dg2 = display.newGroup() local rect3 = display.newRect( 50, 250, 50, 50) local rect4 = display.newRect( 50, 250, 50, 50) local dg2 = display.newGroup() dg2:insert( rect3 ) dg2:insert( rect4 ) transition.to(dg2, { x = 200, y = y, delta = false})

However if I’m not using a display group the two rectangels meet at the absolute parameter:

Works as expected!

local x = display.contentWidth \* 0.5 local y = display.contentHeight \* 0.5 local rect1 = display.newRect( 50, 0, 50, 50) local rect2 = display.newRect( 50, 250, 50, 50) transition.to(rect1, { x = 200, y = y, delta = false}) transition.to(rect2, { x = 200, y = y, delta = false})

Ok, I do understand the reasoning you are saying, that the display groups origin start at 0,0 but shouldn’t they inherit the x and y from it’s objects?

Best regards,

Tomas

#5

No, the group has it’s own x, and y.  Moving the group moves it’s children relative to it.

Rob

#6

Can someone comment on this?

Best regards,

Tomas

#7

delta = false would mean that the values provided to the transition are absolute parameters.  So the origin of the display group (which defaults to 0, 0) will end up at x = 200, y = display.contentHeight * 0.5.  If delta is true, in this case, it will still end up at x = 200 and y = display.contentHeight * 0.5 since delta means to add the right hand side of the existing value of x and y.  Since the x and y start at 0, it works out the same.

Rob

#8

Basically I have two display groups that I want when being touched to go into the middle (let’s say display.contentWidht * 0.5 and display.contentHeight * 0.5). One is in the upper left corner and the other is in the bottom left corner.

It doesn’t matter what I change the delta to in this statement, both the display groups go straight down:

Does not work as expected! Works as if delta was set to true.

local x = display.contentWidth \* 0.5 local y = display.contentHeight \* 0.5 local rect2 = display.newRect( 50, 0, 50, 50) local rect3 = display.newRect( 50, 0, 50, 50) local dg = display.newGroup() dg:insert( rect2 ) dg:insert( rect3 ) transition.to(dg, { x = 200, y = y, delta = false}) local dg2 = display.newGroup() local rect3 = display.newRect( 50, 250, 50, 50) local rect4 = display.newRect( 50, 250, 50, 50) local dg2 = display.newGroup() dg2:insert( rect3 ) dg2:insert( rect4 ) transition.to(dg2, { x = 200, y = y, delta = false})

However if I’m not using a display group the two rectangels meet at the absolute parameter:

Works as expected!

local x = display.contentWidth \* 0.5 local y = display.contentHeight \* 0.5 local rect1 = display.newRect( 50, 0, 50, 50) local rect2 = display.newRect( 50, 250, 50, 50) transition.to(rect1, { x = 200, y = y, delta = false}) transition.to(rect2, { x = 200, y = y, delta = false})

Ok, I do understand the reasoning you are saying, that the display groups origin start at 0,0 but shouldn’t they inherit the x and y from it’s objects?

Best regards,

Tomas

#9

No, the group has it’s own x, and y.  Moving the group moves it’s children relative to it.

Rob