object:setReferencePoint is causing object translation

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#1

Hi,
I have noticed a strange behaviour from the function setReferencePoint to a display object. I’m not sure it is a bug or there is some logical reason for that.
It happens the following:

I display a rectangle.
add it to a group
Rotate the group
move the rectangle.
The rectangle is moved in the x direction relative to the group rotation
group position is not affected

local group=display.newGroup()  
local rect=display.newRect(0,0,200,200)  
group:insert(rect,true)  
group.x, group.y=display.contentWidth/2, display.contentHeight/2  
group:setReferencePoint(display.CenterReferencePoint)  
print("x, y: "..group.x.." "..group.y)  
group:rotate(45)  
rect.x=rect.x+100  
--group:setReferencePoint(display.CenterReferencePoint)  
print("x, y: "..group.x.." "..group.y)

but if I reset the reference point of the group after moving the rectangle, then the rectangle is moved moved as if i had made the addition to the group, not the rectangle

local group=display.newGroup()  
local rect=display.newRect(0,0,200,200)  
group:insert(rect,true)  
group.x, group.y=display.contentWidth/2, display.contentHeight/2  
group:setReferencePoint(display.CenterReferencePoint)  
print("x, y: "..group.x.." "..group.y)  
group:rotate(45)  
rect.x=rect.x+100  
group:setReferencePoint(display.CenterReferencePoint)  
print("x, y: "..group.x.." "..group.y)

If you test the two posted versions you will see the effect.

Is this a bug of the function setReferencePoint or there is a logic behind this behaviour?

Thanks!
Ernest.
[import]uid: 76413 topic_id: 21958 reply_id: 321958[/import]

#2

If you use the center reference point which is the default, images are drawn from the middle as there reference point.

If you then change there reference point (say to top left) the image is drawn from points 0, 0. So it will appear to shift the image as by design it is positioned then at a new reference point. [import]uid: 84637 topic_id: 21958 reply_id: 88710[/import]